Preoperative Assessment Prior to Major Vascular, Non-Cardiac Surgery


Indication Overview

Many patients undergoing major vascular surgery to manage diseases of the aorta and peripheral arteries are at risk for cardiovascular complications during or following the vascular surgery.1 Cardiac complications after non-cardiac surgery depend on specific risk factors, the type of surgery, and the circumstances under which the surgery takes place.2 The major predictors of risk include recent myocardial infarction (MI), severe angina, recent percutaneous coronary intervention, significant arrhythmias, elevated plasma brain natriuretic peptide, diabetes, renal insufficiency, cerebrovascular disease, and obesity.1 The American College of Cardiology/American Heart Association (ACC/AHA) 2007 Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery3 stratify cardiac risk of non-cardiac surgery, according to procedure — vascular surgery is associated with the highest cardiac risk. As such, patients undergoing major non-cardiac vascular surgery should undergo a complete clinical assessment of comorbidities.4 Because of the high prevalence of symptomatic and asymptomatic coronary artery disease (CAD) in this patient population, the clinical assessment aims to identify patients at increased risk of cardiac complications and apply strategies to reduce this risk.5,6

Population: Patients undergoing major high-risk vascular non-cardiac surgery (including aortic and peripheral vascular surgery). Patients undergoing major non-vascular surgeries may also be at risk for cardiac complications; however, the document search for this report was focused on major, high-risk vascular surgery. In some instances, the findings may be generalizable to situations of major non-vascular surgery.

Intervention: Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) with technetium-99m (99mTc)-labelled radiotracers.

As with nuclear imaging for other cardiac indications, the relative distribution of the radionuclide allows for visualization of blood flow through the heart and gives information regarding the functional capacity of the heart.

This identifies patients at greater risk for cardiac complications following surgery so that appropriate testing and therapeutic measures can be taken.1 The basic principle of radionuclide MPI is to administer a radiopharmaceutical intravenously and image blood flow to the heart muscle (myocardial perfusion), both at rest and under stress. Stress is induced by either exercise or a pharmaceutical agent (dobutamine, dipyridamole, or adenosine), which increases coronary blood flow to the myocardium.7 Viable myocardial cells take up the radionuclide tracer (either thallium isotope [201TI] or isotope 99mTc-labelled radiotracer) in proportion to blood flow.7,8 Through sequential image acquisition, the gamma camera works with a computer to evaluate cardiac function and perfusion.9

Comparators: For this report, the following diagnostic tests are considered as alternatives to stress MPI with the 99mTc:

  • Computed tomography (CT) angiography (CTA, computed tomography coronary angiogram [CTCA], cardiac CT)
  • Stress SPECT MPI (using 201TI )
  • Stress echocardiography (Echo) (also called pharmacologic [dobutamine, dipyridamole, or adenosine] echocardiography)
  • Stress magnetic resonance imaging (MRI)
  • Stress positron emission tomography (PET) (using rubidium-82 [Rb-82] or 13N-labelled ammonia [13NH3]).

Preoperative non-invasive testing aims to provide information primarily about coronary artery disease (myocardial ischemia or reduced blood supply to the heart muscle), left ventricular (LV) dysfunction, and heart valve abnormalities in selected patients.2 None of the tests are perfect and some are contraindicated in certain patient populations or clinical situations. Exercise stress tests are often not feasible in patients with peripheral arterial disease (PAD) due, in part, to baseline abnormalities on the resting echocardiogram (ECG).10

Outcomes: Eleven outcomes (referred to as criteria) are considered in this report:

  • Criterion 1: Size of the affected population
  • Criterion 2 : Timeliness and urgency of test results in planning patient management
  • Criterion 3: Impact of not performing a diagnostic imaging test on mortality related to the underlying condition
  • Criterion 4: Impact of not performing a diagnostic imaging test on morbidity or quality of life related to the underlying condition
  • Criterion 5: Relative impact on health disparities
  • Criterion 6: Relative acceptability of the test to patients
  • Criterion 7: Relative diagnostic accuracy of the test
  • Criterion 8: Relative risks associated with the test
  • Criterion 9: Relative availability of personnel with expertise and experience required for the test
  • Criterion 10: Accessibility of alternative tests (equipment and wait times)
  • Criterion 11: Relative cost of the test.

Definitions of the criteria are in Appendix 1.

Methods

The literature search was performed by an information specialist using a peer-reviewed search strategy.

Published literature was identified by searching the following bibliographic databases: MEDLINE with In-Process records and daily updates via Ovid; The Cochrane Library (2011, Issue 3) via Ovid; and PubMed. The search strategy consisted of both controlled vocabulary, such as the National Library of Medicine's MeSH (Medical Subject Headings), and keywords. The main search concepts were radionuclide imaging and non-cardiac surgery, combined with pre-operative assessment or operative complications.

Methodological filters were applied to limit retrieval to health technology assessments, systematic reviews, meta-analyses, randomized controlled trials, and non-randomized studies, including diagnostic accuracy studies. Where possible, retrieval was limited to the human population. The search was also limited to English language documents published between January 1, 2001 and March 7, 2011. Regular alerts were established to update the search until October 2011. Detailed search strategies are located in Appendix 2.

Grey literature (literature that is not commercially published) was identified by searching relevant sections of the CADTH Grey Matters checklist. Google was used to search for additional web-based materials. The searches were supplemented by reviewing the bibliographies of key papers. See Appendix 2 for more information on the grey literature search strategy.

Targeted searches were done as required for the criteria, using the aforementioned databases and Internet search engines. When no literature was identified addressing specific criteria, experts were consulted.

Search Results

There were 11 articles identified through the meta-analyses/systematic review/health technology assessment (MA/SR/HTA) search. Seven were subjected to full-text review, and two were ultimately included.5,11 Three reviews ? published in 1994,6 1996,12 and 199913 ? were excluded, as they were outdated and did not include SPECT stress MPI with 99mTc. One review,14 published in 2002, was excluded, as it did not provide an analysis of relative diagnostic accuracy. An additional publication was excluded as it was a commentary on a systematic review.

Two guidelines of interest were identified in the grey literature search: the ACC/AHA guidelines3 and the European Society of Cardiology guidelines.2 The ACC/AHA guidelines3 include a summary of studies examining the value of MPI for preoperative assessment of cardiac risk, including two studies published after 2001.15,16 Procedure guidelines adopted by the British Cardiovascular Society, British Nuclear Cardiology Society, and British Nuclear Medicine Society,17 and a Consensus Document produced by the Canadian Cardiovascular Society10 were obtained through targeted searching.

Two-hundred and seventy-seven articles were identified in the initial search for primary literature. Thirty-four of these were reviewed in full-text, but none were found to provide estimates of the relative diagnostic accuracy of the various imaging modalities.

Summary table

Table 1: Summary of Criterion Evidence

Domain 1: Criteria Related to the Underlying Health Condition
Criterion Synthesized Information
1 Size of the affected population An estimated 1.7/1,000 (0.17%) Canadians undergo high-risk, non-cardiac surgeries each year. Those with intermediate clinical risk predictors or minor risk predictors and poor functional capacity should undergo preoperative cardiac assessment.

Assuming that the proportion of surgical patients meeting these criteria is between 10% and 50% of those undergoing high-risk, non-cardiac surgeries, the size of the affected population is assumed to be more than 1 in 10,000 (0.01%) and less than 1 in 1,000 (0.1%).
2 Timeliness and urgency of test results in planning patient management The CCS recommends non-invasive testing in select patients scheduled for elective vascular surgery.10 The wait time for the elective surgery dictates the timelines and urgency of the preoperative assessment. According to the Wait Time Alliance, the benchmarks for cardiac nuclear imaging are: "immediate to 24 hours" for emergent cases, "within three days" for urgent cases, and "within 14 days" for scheduled cases.18

While it is understood that the timeliness and urgency of imaging is related to the timeliness and urgency of the surgery, in general, it is assumed that the target time frame for imaging is between eight and 30 days, and obtaining the test results in the appropriate timely manner has significant impact on the management of the condition or the effective use of health care resources.
3 Impact of not performing a diagnostic imaging test on mortality related to the underlying condition The number needed to treat to prevent mortality at one year has been estimated at 221 (95% CI, [confidence interval] 111 to 16,067).19 For patients undergoing aortic surgery, stress testing with or without coronary revascularization is associated with significantly lower rates of perioperative mortality (3.8% versus 9.0%).20

Diagnostic imaging test results can have a moderate impact on mortality.
4 Impact of not performing a diagnostic imaging test on morbidity or quality of life related to the underlying condition Perioperative events that may impact morbidity and quality of life include CHF, unstable angina, and MI. Most studies evaluating the use of SPECT for preoperative evaluation have death, or some combined outcome including death, as their outcome of interest, making it difficult to isolate the impact of not performing the test on patient morbidity or quality of life.

It is assumed that diagnostic imaging test results have moderate impact on morbidity or quality of life.

 

Domain 2: Criteria Comparing 99mTc with an Alternative or Comparing Between Clinical Uses
Criterion Synthesized Information
5 Relative impact on health disparities To be scored locally.
6 Relative acceptability of the test to patients A 2004 British study (of relatively small sample size) compared patient satisfaction and preference toward SPECT MPI versus MRI and found little difference.21 Patients rated the two tests similarly on overall preference, duration, comfort, and safety, with a non-significant preference for MRI on all of the above.21 The only statistically significant finding was that the SPECT scan was preferred in terms of space on the scanner.21

Patients undergoing computed tomography coronary angiography (CTCA) scan may have concerns about radiation exposure and may also feel claustrophobic while in the scanner.

Stress echocardiography (Echo) may be preferred by some patients, as there is no radiation exposure with it. Exercise or pharmacological agents used to induce stress conditions may be unpleasant for some patients.

Because of the closed space of an MRI, patients may experience feelings of claustrophobia, as well as being bothered by the noise. It has been reported that up to 30% of patients experience apprehension and 5% to 10% endure some severe psychological distress, panic, or claustrophobia.22,23 Patients are not exposed to radiation during an MRI scan, which may be more acceptable to some. Exercise or pharmacological agents used to induce stress conditions may be unpleasant for some patients.

Patients may have concerns about radiation exposure and the intravenous injection of a radiopharmaceutical agent associated with stress PET imaging. Exercise or pharmacological agents used to induce stress conditions may be unpleasant for some patients.

SPECT stress MPI with 99mTc-labelled radiotracers:
  • is minimally less acceptable to patients than CTCA
  • is minimally less acceptable to patients than stress Echo
  • has similar patient acceptability as stress MRI
  • is minimally less acceptable to patients than stress PET
  • has similar patient acceptability as stress SPECT with 201TI-labelled radiotracers.
7 Relative diagnostic accuracy of the test

Kertai et al.5 meta-analyzed the prognostic accuracy of six diagnostic tests: radionuclide ventriculography, ambulatory Echo, exercise electrocardiography, MPS, dobutamine stress Echo, and dipyridamole stress Echo. Dobutamine stress Echo showed the highest sensitivity (true positive ratio) to detect cardiac risk of the six tests included in the analysis. The sensitivity of MPS was also found to be high (83% versus 85% with dobutamine stress Echo), but the specificity was lower than dobutamine stress Echo (49% versus 70% with dobutamine stress Echo). Based on the results, the authors concluded the dobutamine stress Echo showed a trend toward better diagnostic performance than the other tests. It should be noted that this systematic review used published reports from January 1975 to April 2001 and that imaging technology has improved significantly in all areas.

Diagnostic Accuracy
Test Sensitivity, % (95% CI) Specificity, % (95% CI)
MPS 83 (77 to 89) 49 (41 to 57)
Dobutamine stress Echo 85 (74 to 97) 70 (62 to 79)
Dipyridamole stress Echo 74 (53 to 94) 86 (80 to 93)

CI = confidence interval; Echo = echocardiography; MPS = myocardial perfusion scintigraphy.

No estimates were identified for the diagnostic accuracy of CTCA, PET, or stress MRI in the preoperative assessment of patients undergoing major vascular, non-cardiac surgery.

Based on the limited evidence available to inform this criterion, it is assumed that the diagnostic accuracy of SPECT MPI with 99mTc-labelled radiotracers is:

  • minimally better than CTCA
  • similar to stress Echo
  • minimally lower than stress MRI
  • minimally lower than stress PET
  • minimally better than SPECT MPI with 201TI-labelled radiotracers.
8 Relative risks associated with the test

Non–radiation-related risks

The main risks of non-invasive preoperative assessment relate to the stress component of the tests (stress SPECT MPI, stress Echo, stress MRI, and stress PET. With exercise stress testing, there is a small risk of patients sustaining an MI if they have significant CAD.24 With dipyridamole stress testing, there are multiple potential side effects, including headache, exacerbated asthma, and heart attack (risk of this event is low).24 With adenosine stress testing, side effects similar to dipyridamole may be experienced. Symptoms of chest pain or pressure may also occur, but these side effects go away quickly once the adenosine administration stops.24 With dobutamine stress testing, some patients may experience light-headedness and nausea. There is a theoretical risk of inducing a fast and abnormal cardiac rhythm (i.e., atrial fibrillation, ventricular tachycardia, ventricular fibrillation); however, this is unlikely with the doses of dobutamine used. A slight risk of MI exists.24 The overall risk of sustaining a heart attack from a stress test is estimated to be about 2 to 4 in 10,000.24

Apart from risks associated with stress testing, a review of undesirable events with radiopharmaceuticals reported anaphylactic reactions and erythmea multiforme (i.e., a type of skin reaction) with sestamibi, although these reactions may be rare.25

With CTCA, some patients may experience an allergic reaction or side effect from the contrast agent. The frequency of severe, life-threatening reactions with the agent gadolinium (Gd) are extremely rare (0.001% to 0.01%) and the frequency of moderate reactions are also rare (0.004% to 0.7%).26 The risks associated with stress testing would not apply for cardiac imaging using CTCA.

Apart from risks associated with stress testing, there is a low risk of adverse events associated with the contrast agent used in stress Echo imaging.

Apart from risks associated with stress testing, MRI is often used in conjunction with the contrast agent Gd. Some patients may experience an allergic reaction to the contrast agent (if required), which may worsen with repeated exposure.27 Side effects of Gd include headaches, nausea, and metallic taste. The frequency of severe, life-threatening reactions with Gd are extremely rare (0.001% to 0.01%) and the frequency of moderate reactions are also rare (0.004% to 0.7%)26

Apart from risks associated with stress testing, the Pharmacopeia Committee of the Society of Nuclear Medicine conducted a four-year prospective evaluation of adverse reactions to PET and reported no adverse reactions among the 33,925 scans conducted in 22 participating PET centres in the United States.28

Radiation-related Risks

Among the modalities to assess patients prior to major vascular, non-cardiac surgery, 99mTc-SPECT MPI, 201Tl-SPECT MPI,  CTCA, and PET expose the patient to ionizing radiation. The average effective dose of radiation delivered with each of these procedures can be found in the subsequent table:

Effective Doses of Radiation
Procedure Average Effective Dose (mSv)
99mTc-SPECT MPI 7 to 12.829
201Tl-SPECT MPI 17 to 4129,30
Cardiac 18FDG-PET 7(MIIMAC expert opinion) to 1430
Cardiac 82Rb-PET 1.1 to 5.030-32
Cardiac 13NH3-PET 1.5 to 2.232
CTCA 2.1 to 1633,34
Stress MRI 0
Stress Echo 0
Average background dose of radiation per year 1-3.035-37

CTCA = computed tomography coronary angiography; Echo = echocardiogram; 18FDG =18F-fluorodeoxyglucose; MIIMAC = Medical Isotopes and Imaging Modalities Advisory Committee; MRI = magnetic resonance imaging; mSv = millisievert;13NH3 = 13N-labelled ammonia; PET = positron emission tomography; 82Rb = rubidium-82; SPECT = single-photon emission computed tomography; 99mTc = Technitium-99m; 201TI = thallium-201.

Overall, 99mTc-SPECT MPI:

  • and CTCA have similar safety profiles
  • and stress Echo have similar safety profiles
  • and stress MRI have similar safety profiles
  • and stress PET have similar safety profiles
  • and 201TI-SPECT have similar safety profiles.
9 Relative availability of personnel with expertise and experience required for the test

In Canada, physicians involved in the performance, supervision, and interpretation of diagnostic nuclear imaging, CT scans, MRI, and U/S should be diagnostic radiologists or nuclear medical physicians. According to the CMA, there are 1,149 practicing cardiologists in Canada.38 Not all radiologists, nuclear medical physicians, nuclear cardiologists, or cardiologists have the expertise to conduct 99mTc-SPECT and all of its alternatives. For example, a 2002 report by the CCS reported that 43% of cardiologists do Echo.

Assuming the necessary equipment is available, if 99mTc-SPECT imaging is not available it is assumed that:

  • 25% to 74% of the procedures can be performed in a timely manner using CTCA
  • 25% to 74% of the procedures can be performed in a timely manner using Echo
  • fewer than 25% of the procedures can be performed in a timely manner using MRI
  • 25% to 74% of the procedures can be performed in a timely manner using PET
  • more than 95% of the procedures can be performed in a timely manner using 201TI-SPECT.
10 Accessibility of alternative tests (equipment and wait times)

For SPECT MPI, nuclear medicine facilities with gamma cameras (including SPECT) are required. As of January 1, 2007, there was an average of 18.4 nuclear medicine cameras per million people, with none available in the YT, NT, or NU.39

A report from the CIHI states that, as of January 1, 2007, CT scanners were available at a rate of 12.8 per million people in Canada; however, there were none available in NU.39 For CT scanners, the average weekly use ranged from 40 hours in PEI to 69 hours in Ontario, with a national average of 60 hours.39 In 2010, the average wait time for a CT scan in Canada was 4.2 weeks.40

As of January 1, 2007, there were 6.8 MRI devices per million population in Canada, with no MRI scanners available in YT, NT, or NU.39 According to CIHI's National Survey of Selected Medical Imaging Equipment database, the average number of hours of operation per week for MRI scanners in 2006–2007 ranged from 40 hours in PEI to 99 hours in Ontario, with a national average of 71 hours.39 In 2010, the average wait time for MR imaging in Canada was 9.8 weeks.40

U/S machines are widely available across the country. According to the Fraser Institute, the average wait time for U/S in 2010 was 4.5 weeks.40

Assuming the necessary personnel is available, if 99mTc-SPECT imaging is not available it is assumed that:

  • 25% to 74% of the procedures can be performed in a timely manner using CTCA
  • 75% to 94% of the procedures can be performed in a timely manner using Echo
  • fewer than 25% of the procedures can be performed in a timely manner using MRI
  • fewer than 25% of the procedures can be performed in a timely manner using PET
  • more than 95% of the procedures can be performed in a timely manner using 201TI-SPECT.
11 Relative cost of the test

According to our estimates, the cost of MPI with 99mTc-based radioisotopes is $964.53. The cost of MPI with 201TI or with PET is assumed to be greater than imaging with 99mTc-based radioisotopes. Stress MRI is minimally less costly than MPI with 99mTc. CTCA and stress Echo are moderately less costly.

Relative Costs
Test Total Costs ($) Cost of Test Relative to 99mTc-based Test ($)
99mTc-SPECT MPI 964.53 Reference
201TI-SPECT MPI 964.53 +0.00
CTCA 506.03 –458.50
Stress echo 466.90 –497.63
Stress MRI 835.16 –129.37
Stress PET 1128.60 +164.07

 

CAD = coronary aretery disease; CCS = Canadian Cardiovascular Society; CHF = congestive heart failure; CI = confidence interval; CIHI = Canadian Institute for Health Information; CT = computed tomography; CTCA = computed tomography coronary angiography; Echo = echocardiography; Gd = gadolinium; MI = myocardial infarction; MPI = myocardial perfusion imaging; MPS = myocardial perfusion scintigraphy;  MRI = magnetic resonance imaging; mSv = millisevert; NU = Nunavut; NT = Northwest Territories; PEI = Prince Edward Island; PET = positron emission tomography; SPECT = single-photon emission computed tomography; 99mTc = technetium-99m; 201TI = thallium-201; U/S = ultrasound; YT = Yukon.

Criterion 1: Size of affected population (link to definition)

CCS estimates that nearly 500,000 Canadians undergo non-cardiac surgery each year; however, only a subset of these patients require preoperative risk assessment.10 Preoperative non-invasive risk assessment is recommended in patients undergoing intermediate risk or vascular surgery with a low (< 4 metabolic equivalents of task [METs]) or unknown functional capacity and 1 or more clinical risk factors (ischemic heart disease, compensated or prior heart failure, diabetes mellitus, renal insufficiency, cerebrovascular disease) if testing may change management.10 In emergent cases, or in elective cases in which the patient has had revascularization or a favourable result on a coronary evaluation in the past two to five years, and has been asymptomatic since, no testing is required.10 Similarly, patients with the functional capacity to walk more than one to two blocks and no risk predictors can proceed directly to operation without preoperative assessment.10

Targeted literature searches were conducted in order to estimate the size of the population undergoing high-risk non-cardiac surgical procedures in Canada on an annual basis. Table 2 shows estimated numbers of major vascular procedures performed in Canada annually.

Table 2: Major Vascular Procedures Performed in Canada Annually

Procedure Number Performed in Canada Per Year
Aortic Repair
AAA repair Overall, 2,948 AAA procedures (open repair and EVAR) were performed in nine provinces across Canada in 2008 (data for Quebec are not included),41 with an estimated prevalence of 1.2/10,000 (0.012%).
Peripheral Vascular Surgery
CEA (used to prevent stroke, by correcting stenosis or narrowing in the common carotid artery) Approximately 5,500 CEA procedures were reported during a one-year period (2000–2001),42 with an estimated prevalence of 1.79/10,000 (0.0179%).
Peripheral vascular bypass (also known as a lower extremity bypass):
rerouting of blood flow around an obstructed artery that supplies blood to the legs and feet
126 per 100,000 in the US in 2006,43 with an estimated prevalence of 1.26/1,000 (0.126%).
Lower extremity amputation 503 in Alberta in 2007,44 with an estimated prevalence of 1.43/10,000 (0.0143%).
TOTAL Estimated prevalence of 1.7/1,000 (0.17%)

AAA = abdominal aortic aneurysm; CEA = carotid endarterectomy; EVAR = endovascular aneurysm repair.

No literature indicating the proportion of these vascular surgeries for which preoperative risk assessment is indicated was identified.

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Criterion 2: Timeliness and urgency of test results in planning patient management (link to definition)

In the case of emergency surgical procedures, such as those for a ruptured abdominal aortic aneurysm (AAA) or major trauma, cardiac evaluation will not change the course of the surgical intervention, but may influence the immediate post-operative patient management strategy.2 In the case of elective surgeries, the results of the preoperative assessment may influence the choice of intervention, or the decision as to whether to intervene at all.2 For this reason, CCS only recommends non-invasive testing in select patients scheduled for elective vascular surgery.10 The wait time for the elective surgery may dictate the urgency of the preoperative assessment. For example, the greatest benefit of carotid endarterectomy (CEA) for preventing recurrent stroke is when surgery is performed within two weeks after ischemic stroke or transient ischemic attack.45 Results from the Registry of the Canadian Stroke Network indicate that the benefit of CEA is reduced when surgery is delayed more than two weeks and essentially lost if delayed more than three months.45 According to the Wait Time Alliance, the benchmarks for cardiac nuclear imaging are: "immediate to 24 hours" for emergent cases, "within three days" for urgent cases, and "within 14 days" for scheduled cases.18

Return to Summary Table.

Criterion 3: Impact of not performing a diagnostic imaging test on mortality related to the underlying condition (link to definition)

Failure to perform a preoperative assessment prior to non-cardiovascular surgery may influence patient mortality, as demonstrated by three retrospective analyses.

An Ontario-based study published in 201146 evaluated the post-operative survival of patients over the age of 40 years undergoing elective intermediate to high-risk non-cardiac surgery (April 1, 1999 to March 31, 2008). The study cohort consisted of 264,823 patients, 40,084 of whom underwent Echo testing within the six months prior to surgery.46 Eighty-nine percent (n = 35,498) of the Echo patients were matched to no Echo controls, creating a matched cohort of 70,996 patients. Within the matched cohort, preoperative Echo was associated with a small, statistically significant increase in post-operative mortality (relative risk [RR] = 1.14 at 30 days, RR = 1.07 at one year).46 The authors concluded that the practice of conducting preoperative Echo may not improve patient mortality.46

A previous analysis by the same group of authors investigated the impact of non-invasive cardiac stress testing before elective intermediate- to high-risk non-cardiac surgery on mortality.19 Patients (n = 23,060) over the age of 40 who underwent stress testing prior to surgery were retrospectively matched with patients who did not undergo stress testing (including graded exercise treadmill testing, nuclear perfusion imaging, and stress Echo). Patients who underwent testing were typically male, and testing was more likely to be conducted at a high- or moderate-volume teaching hospital. Mortality data was collected using the Canadian Institute for Health Information discharge abstract database (in-hospital death) and the Registered Persons Database (out-of-hospital deaths). Within the matched cohort, one year survival was higher among patients who had undergone preoperative testing than in those who had not (hazard ratio [HR] = 0.92, 95% confidence interval [CI], 0.86 to 0.99). Of the patients who underwent stress testing, 914 (3.8%) underwent coronary angiography, 149 (0.6%) underwent percutaneous coronary intervention, and 134 underwent coronary artery bypass graft surgery between the dates of the stress testing and the surgery. The number needed to treat to prevent mortality at one year was calculated to be 221 (95% CI, 111 to 16,067). This number represents the average number of patients who need to be imaged in order to prevent one death. It is calculated by taking the inverse of the absolute risk reduction.

In 1999, Fleisher et al.20 investigated mortality rates following vascular surgery using retrospective cohort analysis. The cohort (n = 6,895) was based on a sample of Medicare patients who underwent major vascular surgery in the first six months of 1991 and the first 11 months of 1992.20 The six-month period prior to each index case was reviewed in order to determine whether preoperative non-invasive cardiovascular imaging or coronary revascularization was performed. The primary study outcome was death within 30 days of surgery.20 Forty-two per cent of the cohort underwent aortic surgery and the remaining 58% had peripheral vascular surgery.20 For patients undergoing aortic surgery, stress testing with or without coronary revascularization was associated with significantly lower rates of perioperative mortality (3.8% versus 9.0%).20

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Criterion 4: Impact of not performing a diagnostic imaging test on morbidity or quality of life related to the underlying condition (link to definition)

Perioperative events that may impact morbidity and quality of life include congestive heart failure, unstable angina, and MI. Most studies evaluating the use of SPECT for preoperative evaluation have death, or some combined outcome including death, as their outcome of interest, making it difficult to isolate the impact of not performing the test on patient morbidity or quality of life.

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Criterion 5: Relative impact on health disparities (link to definition)

Disparity concerns have been documented with respect to the following disadvantaged groups.

Diabetic patients
According to a report by Hashimoto et al., perioperative cardiac events are more common among patients with diabetes mellitus (DM) than in non-DM patients (RR: 2.6).47 The usefulness of SPECT in assessing perioperative cardiac risk in DM patients with cardiac disease undergoing peripheral vascular surgery has been well-described.47-49 Most recently, Bai et al.50 evaluated the use of SPECT in the preoperative evaluation of diabetic patients without chest pain. There were a number of limitations associated with this study, including the fact that undergoing SPECT was part of the patient inclusion criteria, which likely inflated the frequency of cardiac events.50 The authors concluded that DM patients undergoing high-risk operations should be particularly concerned with abnormal SPECT findings.50

Elderly patients
While the use of MPI has been extensively evaluated in young and middle-aged patients, there are limited guidelines regarding its application in the elderly.51 A 2006 study by Bai et al.52 investigated the increased perioperative cardiac risk in the elderly using a retrospective analysis. The records of 1,570 patients who had undergone dipyridamole stress myocardial perfusion SPECT before non-cardiac surgery were review and divided into four groups:

  • aged 75 or more, normal SPECT (Group 1-E) n = 270
  • aged less than 75, normal SPECT (Group 1-Y) n = 729
  • aged 75 or more, abnormal SPECT (Group 2-E) n = 93
  • aged less than 75, abnormal SPECT (Group 2-Y) n = 259.

The rate of cardiac events (cardiac death, non-fatal MI, heart failure, or arrhythmias) in the groups undergoing high-risk surgeries were 4.4% (Group 1-E), 4.2% (Group 1-Y), 26.3% (Group 2-E), and 15.4% (Group 2-Y). The authors concluded that aging itself does not influence perioperative cardiac risk in patients with normal SPECT results. In patients with MI or ischemia documented by SPECT, the likelihood of cardiac events increases with age, independently of other clinical variables.

Obese patients
Investigations of obese patients may be limited by their weight or size. Radiographs and Echo may be of poor quality, while some patients may be too big to undergo imaging techniques such as CT or MRI.53

Patients at low-volume hospitals
There is considerable evidence to support the hypothesis that patients undergoing high-risk surgeries at high-volume hospitals have better health outcomes, including lower risk of post-operative death, than do patients at low-volume hospitals.54-56 In 2003, Urbach et al. collected data on patients undergoing five major surgical procedures in Ontario and analyzed the relationship between patient outcomes and the average annual volume of the hospital in which the procedure took place.57 The authors concluded that there is evidence that a small number of operative deaths could be prevented by restricting four complex surgical procedures, including AAA, to high-volume hospitals.

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Criterion 6: Relative acceptability of the test to patients (link to definition)

SPECT MPI
A 2004 British study compared patient satisfaction and preference toward SPECT versus MRI adenosine stress myocardial perfusion scans and found little difference.58 Forty-one patients who had undergone both SPECT and MRI were sent a retrospective questionnaire within two weeks of scan completion. Thirty-five completed questionnaires were returned. When asked "If the two tests (nuclear heart scan and MRI) could provide the same information, which of the two would you prefer?" 12 patients (34%) stated a preference for MRI, nine (26%) stated a preference for SPECT, and 14 (40%) stated no preference.58 Patients rated the two tests similarly on overall preference, duration, comfort, and safety, with a non-significant preference for MRI on all of the aforementioned.58 The only statistically significant finding was that the SPECT scan was preferred in terms of space on the scanner.58 Three participants (9%) stated that they would not have an MRI again, while two patients (6%) said they would not repeat a SPECT.58 The study authors recognized that the relatively small sample size may have affected their ability to demonstrate statistically significant preference for one scan over the other.58 Exercise or pharmacological agents used to induce stress conditions may be unpleasant for some patients.

Computed Tomography Coronary Angiography (CTCA)
Patients undergoing CT scan may have concerns about radiation exposure and may also feel claustrophobic while in the scanner. This may be less of a problem with new CT scanners, if available (Medical Isotopes and Imaging Modalities Advisory Committee [MIIMAC] expert opinion). Patients may also be required to hold their breath for a substantial period of time, which is seen as "uncomfortable" and "difficult."59

Stress Echo
This test is likely to be well-tolerated by patients. Echo may be preferred by some patients, as there is no radiation exposure. Exercise or pharmacological agents used to induce stress conditions may be unpleasant for some patients.

Stress MRI
Because of the closed space of an MRI, patients may experience feelings of claustrophobia, as well as being bothered by the noise. This may be less of a problem with new MRI machines, if available (MIIMAC expert opinion). It has been reported that up to 30% of patients experience apprehension and 5% to 10% endure some severe psychological distress, panic, or claustrophobia.22,23 Some patients may have difficulty remaining still during the scan. Patients are not exposed to radiation during a MRI scan, which may be more acceptable to some. Exercise or pharmacological agents used to induce stress conditions may be unpleasant for some patients.

Stress PET Myocardial Perfusion Imaging (rubidium-82 [82Rb] or 13N-labelled ammonia [13NH3])
Patients may have concerns about radiation exposure and the intravenous injection of a radiopharmaceutical agent. Exercise or pharmacological agents used to induce stress conditions may be unpleasant for some patients.

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Criterion 7: Relative diagnostic accuracy of the test (link to definition)

Systematic Reviews and Meta-analyses

Two systematic reviews and meta-analyses reported on the relative accuracy of stress MPI and its alternatives at predicting perioperative cardiac risk in patients undergoing major vascular surgery. Two reviews, published in 19946 and 1996,12 were excluded, as they were outdated and did not include SPECT stress MPI with 99mTc. An additional review,14 published in 2002, was excluded, as it did not provide an analysis of relative diagnostic accuracy. No estimates were identified for the diagnostic accuracy of CTCA, PET, or stress MRI in the preoperative assessment of patients undergoing major vascular, non-cardiac surgery.

Kertai et al. (2003)5 meta-analyzed the prognostic accuracy of six diagnostic tests: radionuclide ventriculography (with 99mTc), ambulatory electrocardiography, exercise electrocardiography, myocardial perfusion scintigraphy (including both planar and SPECT, 99mTc and 201TI), dobutamine stress Echo, and dipyridamole stress Echo. This systematic review included published reports from January 1975 to April 2001; imaging technology has improved significantly in all areas in the past decade. This study was included in the current report despite the fact that the authors did not provide separate analyses for 99mTc and 201Tl. It is possible that the sensitivity and specificity of 99mTc is lower or higher than the pooled value. This study was included based on the limited available information for comparing 99mTc-based imaging to its comparators; however, the limitations of the study should be noted. The results of the analysis are presented in Table 3. A MEDLINE search for English language articles published between January 1975 and April 2001 was conducted, with additional references obtained from the bibliographies of review articles and original papers. If several studies on the same patient population were identified, the report with the largest sample size was selected. Studies in which a positive test result led to preoperative coronary revascularization were included in the analysis only if the revascularized patients could be excluded or analyzed separately. Data were extracted by two independent reviewers, with discrepancies resolved by consensus. Fifty-eight studies were included in the meta-analysis. Random effects models were used to calculate weighted sensitivity and specificity from the published results. Dobutamine stress Echo showed the highest sensitivity (true positive ratio) to detect cardiac risk of the six tests included in the analysis. The sensitivity of myocardial perfusion scintigraphy was also high (83% versus 85% with dobutamine stress Echo), but the specificity was a lower than dobutamine stress Echo (49% versus 70% with dobutamine stress Echo). Based on the results, the authors concluded the dobutamine stress Echo showed a trend toward better diagnostic performance than the other tests.

Table 3: Sensitivity and Specificity Values Reported by Kertai et al.5

Test No. of Studies No. of Patients No. of Events Sensitivity, % (95% CI) Specificity, % (95% CI)
Radionuclide ventriculography 8 532 54 50 (32 to 69) 91 (87 to 96)
Ambulatory electrocardiography 8 893 52 52 (21 to 84) 70 (57 to 83)
Exercise electrocardiography 7 685 25 74 (60 to 88) 69 (60 to 78)
Myocardial perfusion scintigraphy 23 3119 207 83 (77 to 89) 49 (41 to 57)
Dobutamine stress Echo 8 1877 82 85 (74 to 97) 70 (62 to 79)
Dipyridamole stress Echo 4 850 33 74 (53 to 94) 86 (80 to 93)

CI = confidence interval; Echo = echocardiography; No. = number.

Stress Echo versus SPECT with 201T-labelled radiotracers
Beattie et al.11 conducted a meta-analysis comparing preoperative stress Echo and nuclear scintigraphy imaging, published in 2006. Two searches were conducted in March 7, 2005 using MEDLINE: one for 201TI-imaging and the other for stress Echo. There was no language restriction used. The resulting 111 citations were reviewed by two authors. Sixty-eight studies were included in the meta-analysis: 25 assessing stress Echo and 50 assessing thallium (seven studies were direct comparisons). The likelihood ratio (Sensitivity/[1-Specificity]) was the primary outcome measure in the study. The results of the meta-analysis indicate that a positive stress Echo results in a likelihood ratio twice as predictive as a positive 201TI-imaging (4.09 versus 1.83) for predicting post-operative cardiac events. These results are consistent with the results of the review by Kertai et al: stress Echo has superior negative predictive ability when compared with 201TI-imaging. The authors concluded that stress Echo is superior to 201TI-imaging in predicting post-operative cardiac events.

Primary Studies

Two-hundred and seventy-seven articles were identified in the initial search for primary literature. Thirty-four of these were reviewed in full-text. No estimates of diagnostic accuracy were provided.

Return to Summary Table.

Criterion 8: Relative risks associated with the test (link to definition)

Non–radiation-related risks

Cardiac stress tests
The main risks of non-invasive preoperative assessment relate to the stress component of the tests:

  • With exercise stress testing, there is a small risk of patients sustaining an MI if they have significant coronary artery disease.24
  • With dipyridamole stress testing, there are multiple potential side effects, including headache, exacerbated asthma, and heart attack (risk of this event is low).24
  • With adenosine stress testing, side effects similar to dipyridamole may be experienced. Symptoms of chest pain or pressure may also occur, but these side effects go away quickly once the adenosine administration stops.24
  • With dobutamine stress testing, some patients may experience light-headedness and nausea. There is a theoretical risk of inducing a fast and abnormal cardiac rhythm (i.e., atrial fibrillation, ventricular tachycardia, ventricular fibrillation); however, this is unlikely with the doses of dobutamine used. A slight risk of MI exists.24

The overall risk of sustaining a heart attack from a stress test is estimated to be about 2 to 4 in 10,000.24

Stress SPECT
Apart from risks associated with stress testing, a review of undesirable events with radiopharmaceuticals reported anaphylactic reactions and erythemea multiforme (i.e., a type of skin reaction) with sestamibi, although these reactions may be rare.25

CTCA
Some patients may experience an allergic reaction to the contrast agent (if required), which may worsen with repeated exposure.27 In addition, patients may experience mild side effects such as nausea, vomiting, or hives from the contrast agent. A 2009 retrospective review of all intravascular doses of low-osmolar iodinated and gadolinium (Gd) contrast materials administered at the Mayo Clinic between 2002 and 2006 (456,930 doses) found that 0.15% of patients given CT contrast material experienced side effects, most of which were mild. A serious side effect was experienced by 0.005% of patients.60 CT is contraindicated in patients with elevated heart rate, hypercalcemia, and impaired renal function. Patients must be able to take rate-lowering medications. Although rarely used in cardiac imaging, Gd is contraindicated in patients with renal failure or end-stage renal disease, as they are at risk of nephrogenic systemic fibrosis. According to the American College of Radiology Manual on Contrast Media,26 the frequency of severe, life-threatening reactions with Gd are extremely rare (0.001% to 0.01%). Moderate reactions resembling an allergic response (i.e., rash, hives, urticaria) are also very unusual and range in frequency from 0.004% to 0.7%.26 The risks associated with stress testing would not apply for cardiac imaging using CTCA.

Stress Echo
Apart from risks associated with stress testing, three relatively large studies — with sample sizes of 42,408 patients (2009),61 26,774 patients (2009),62 and 5069 patients (2008)63 —compared cardiac outcomes (non-fatal MI or death) between patients who underwent contrast-enhanced Echo with patients who had an Echo without contrast. All three studies concluded that the risk of an adverse event is low and is no different than for patients who received no contrast. No additional risks associated with Echo were identifed.

Stress MRI
Apart from risks associated with stress testing, MRI is contraindicated in patients with metallic implants including pacemakers.64 MRI is often used in conjunction with the contrast agent Gd. Some patients may experience an allergic reaction to the contrast agent (if required), which may worsen with repeated exposure.27 Side effects of Gd include headaches, nausea, and metallic taste. Gd is contraindicated in patients with renal failure or end-stage renal disease, as they are at risk of nephrogenic systemic fibrosis. According to the American College of Radiology Manual on Contrast Media,26 the frequency of severe, life-threatening reactions with Gd are extremely rare (0.001% to 0.01%). Moderate reactions resembling an allergic response (i.e., rash, hives, urticaria) are also very unusual and range in frequency from 0.004% to 0.7%.26

Stress PET myocardial perfusion imaging (82Rb or 13NH3)
Apart from risks associated with stress testing, the Pharmacopeia Committee of the Society of Nuclear Medicine conducted a four-year prospective evaluation of adverse reactions to PET and reported no adverse reactions among the 33,925 scans conducted in 22 participating PET centres in the United States.28 The risks associated with stress testing would apply for cardiac imaging using PET.

Radiation-related risks

Among the modalities to assess patients prior to major vascular, non-cardiac surgery, 99mTc-SPECT MPI, 201Tl-SPECT MPI, CTCA, and PET expose the patient to ionizing radiation. The average effective dose of radiation delivered with each of these procedures can be found in Table 4.

Table 4: Effective Doses of Radiation

Procedure Average Effective Dose (mSv)
99mTc-SPECT MPI 7 to 12.829
201Tl-SPECT MPI 17 to 4129,30
Cardiac 18FDG-PET 7(MIIMAC expert opinion) to 1430
Cardiac 82Rb-PET 1.1 to 5.030-32
Cardiac 13NH3-PET 1.5 to 2.232
CTCA 2.1 to 1633,34
MRI 0
Echo 0
Average background dose of radiation per year 1-3.035-37

CTCA = computed tomography coronary angiography; Echo = echocardiography; 18FDG- PET = 18fluorodeoxyglucose-positron emission tomography; MPI = myocardial perfusion imaging; MRI = magnetic resonance imaging; mSv = millisevert; 13NH3 = 13N-labelled ammonia; PET = positron emission tomography; 82Rb = rubidium-82; SPECT = single-photon emission computed tomography; 99mTc = Technitium-99m; 201Tl =Thallium-201.

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Criterion 9: Relative availability of personnel with expertise and experience required for the test (link to definition)

The patient's primary physician or surgeon may request a cardiology consultation prior to conducting major vascular surgery. According to the ACC/AHA 2007 Perioperative Guidelines, the role of the consultant is to determine the stability of the patient's cardiovascular status.3 The consultant may recommend changes in medication, preoperative tests or procedures, or higher levels of post-operative care.3

The personnel required for the performance of the imaging tests to assess patients undergoing major vascular, non-cardiac surgery are presented by imaging modality. A summary of the availability of personnel required for the conduct of methods to assess patients undergoing major vascular, non-cardiac surgery, by SPECT or any of the alternative imaging modalities, is provided in Table 5.

99mTc-labelled radiotracer SPECT MPI
In Canada, physicians involved in the performance, supervision, and interpretation of cardiac nuclear imaging (specifically MPI using 99mTc-labelled radiotracer) should be nuclear medicine physicians with particular expertise in nuclear cardiology (nuclear cardiologists). Cardiologists also provide much of the nuclear cardiology services. According to the Canadian Medical Association (CMA), there are 1,149 practising cardiologists in Canada.38

Nuclear medicine technologists are required to conduct MPI. Technologists must be certified by the Canadian Association of Medical Radiation Technologists (CAMRT) or an equivalent. A stress technologist or dedicated physician should be on hand to monitor any procedures involving stress testing.

All alternative imaging modalities
In Canada, physicians involved in the performance, supervision, and interpretation of diagnostic CT scans, MRI, and ultrasound should be diagnostic radiologists39 and must have a Fellowship or Certification in Diagnostic Radiology with the Royal College of Physicians and Surgeons of Canada and/or the Collège des médecins du Québec. Foreign-trained radiologists also are qualified if they are certified by a recognized certifying body and hold a valid provincial license.65 According to the CMA, there are 1,149 practicing cardiologists in Canada.38

Medical radiation technologists (MRTs) must be certified by the CAMRT, or an equivalent licensing body. A stress technologist or dedicated physician should be on hand to monitor any procedures involving stress testing.

Service engineers are needed for system installation, calibration, and preventive maintenance of the imaging equipment at regularly scheduled intervals. The service engineer's qualification will be ensured by the corporation responsible for service and the manufacturer of the equipment used at the site.

Qualified medical physicists (on site or contracted-part time) should be available for the installation, testing, and ongoing quality control of CT scanners, MR scanners, and nuclear medicine equipment.65

CTCA
CTCA is a CT-based test. In some jurisdictions, cardiologists provide much of the CTCA service. According to the CMA, there are 1,149 practicing cardiologists in Canada.38

For the performance of CT scan, medical radiation technologists who are certified by the CAMRT, or an equivalent licensing body recognized by CAMRT, are required. The training of technologists specifically engaged in CT should meet with the applicable and valid national and provincial specialty qualifications.

Stress Echo
Echo is an ultrasound-based test. Cardiologists provide much of the Echo service. A 2002 report by the CCS reported that 43% of cardiologists do Echo. According to the CMA, there are 1,149 practicing cardiologists in Canada38 It is assumed that less than 500 of them do Echo.

Sonographers (or ultrasonographers) should be graduates of an accredited school of sonography or have obtained certification by the Canadian Association of Registered Diagnostic Ultrasound Professionals. They should be members of their national or provincial professional organization. Sonography specialties include general sonography, vascular sonography, and cardiac sonography.39 In Quebec, sonographers and medical radiation technologists are grouped together; in the rest of Canada, sonographers are considered a distinct professional group.39 A stress technologist or dedicated physician should be on hand to monitor any procedures involving stress testing.

Stress MRI
Medical technologists must have CAMRT certification in magnetic resonance or be certified by an equivalent licensing body recognized by CAMRT. A stress technologist or dedicated physician should be on hand to monitor any procedures involving stress testing.

Stress PET
In Canada, physicians involved in stress PET scanning should be nuclear medicine physicians, nuclear cardiologists, or cardiologists with training and expertise in nuclear imaging. In Canada, physicians who perform PET imaging studies must be certified by either the Royal College of Physicians and Surgeons of Canada or le Collège des médecins du Quebec.

Technologists must be certified by CAMRT or an equivalent licensing body. A stress technologist or dedicated physician should be on hand to monitor any procedures involving stress testing.

Table 5: Medical Imaging Professionals in Canada, 200639

Jurisdiction Diagnostic Radiology Physicians Nuclear Medicine Physicians MRTs Nuclear Medicine Technologists Sonographers Medical Physicists
NL 46 3 263 15 NR NR
NS 71 5 403 71 NR NR
NB 47 3 387 55 NR NR
PEI 7 0 57 3 NR 0
QC 522 90 3,342 460 NR NR
ON 754 69 4,336 693 NR NR
MB 58 8 501 42 NR NR
SK 61 4 359 36 NR NR
AB 227 18 1,229 193 NR NR
BC 241 21 1,352 212 NR NR
YT 0 0 0 0 NR 0
NT 0 0 26 1 NR 0
NU 0 0 0 0 NR 0
Total 2,034 221 12,255 1,781 2,900* 322*

AB = Alberta; BC = British Columbia; MB = Manitoba; MRT = medical radiation technologist; NB = New Brunswick; NL = Newfoundland and Labrador; NR = not reported by jurisdiction; NS = Nova Scotia; NT= Northwest Territories; NU = Nunavut; PEI= Prince Edward Island; ON = Ontario; QC = Quebec; YT = Yukon.

* This represents a total for all of the jurisdictions.

Return to Summary Table.

Criterion 10: Accessibility of alternative tests (equipment and wait times) (link to definition)

There are notable variations in the availability of medical imaging technologies across Canada. Table 6 provides an overview of the availability of equipment required to conduct a preoperative assessment of patients undergoing major vascular, non-cardiac surgery. Data for nuclear medicine cameras (including SPECT) are current to January 1, 2007. The number of CT, MRI, and SPECT/CT scanners is current to January 1, 2010. Information on the availability of PET and PET/CT scanners is current to November 30, 2010. Data were not available for Echo.

Table 6: Diagnostic Imaging Equipment in Canada39,66

  Nuclear Medicine Cameras CT Scanners MRI Scanners PET or PET/CT
Number of devices 60339 46066 21866 3666
Average number of hours of operation per week (2006-2007) 40 60 71 NA
Provinces and Territories with no devices available YT, NT, NU NU YT, NT, NU NL, PEI, SK, YT, NT, NU

CT = computed tomography; PET = positron emission tomography; MRI = magnetic resonance imaging; NB = New Brunswick; NL. = Newfoundland; NS = Nova Scotia; NU = Nunavut; NT = Northwest Territories; PEI = Prince Edward Island; SK = Saskatchewan; YT = Yukon.

99mTc-labelled radiotracer SPECT
Nuclear medicine facilities with gamma cameras are required for SPECT imaging. Three jurisdictions — the Yukon, the Northwest Territories, and Nunavut — do not have any nuclear medicine equipment.39

CT
No CT scanners are available in Nunavut.39 The average weekly use of CT scanners ranged from 40 hours in PEI to 69 hours in Ontario, with a national average of 60 hours.39 In 2010, the average wait time for a CT scan in Canada is 4.2 weeks.40 The average wait time for CTCA was not reported.

Echo
No information was found to identify how many Echo machines are available in Canada.

MRI
No MRI scanners are available in the Yukon, Northwest Territories, or Nunavut.39 According to Canadian Institute for Health Information's National Survey of Selected Medical Imaging Equipment database, the average number of hours of operation per week for MRI scanners in 2006–2007 ranged from 40 hours in Prince Edward Island to 99 hours in Ontario, with a national average of 71 hours.39 In 2010, the average wait time for MRI in Canada was 9.8 weeks.40

PET
A 2010 Environmental Scan published by CADTH reported that there are approximately 31 Canadian centres equipped to perform PET scans.67 These centres are located in the provinces of: British Columbia, Alberta, Manitoba, Ontario, Quebec, New Brunswick, and Nova Scotia.67 There are 36 PET or PET/CT scanners in Canada, four of which are used for research purposes only.67

Wait times
Wait time benchmarks for cardiac nuclear imaging set by the Wait Time Alliance68 are immediate to 24 hours for emergency cases (immediate danger to life, limb, or organ); within three days for urgent cases (situation that is unstable and has the potential to deteriorate quickly and result in an emergency admission); and within 14 days for scheduled cases (situation involving minimal pain, dysfunction, or disability — routine or elective).

Return to Summary Table.

Criterion 11: Relative cost of the test (link to definition)

Fee codes from the Ontario Schedule of Benefits were used to estimate the relative costs of SPECT MPI and its alternatives. Technical fees are intended to cover costs incurred by the hospital (i.e., radiopharmaceutical costs, medical/surgical supplies, and non-physician salaries). Maintenance fees are not billed to OHIP; estimates here were provided by St. Michael's Hospital in Toronto. Certain procedures (i.e., PET scan, CT scan, MRI scan) are paid for, in part, out of the hospital's global budget — estimates here were provided by The Ottawa Hospital. It is understood that the relative costs of imaging will vary from one institution to the next.

According to our estimates (Table 7), the cost of MPI with 99mTc-based radioisotopes is $964.53. The cost of MPI with 201TI or with PET is assumed to be greater than imaging with 99mTc-based radioisotopes. Stress MRI is minimally less costly than MPI with 99mTc. CTCA and stress Echo are moderately less costly.

Table 7: Cost Estimates Based on the Ontario Schedule of Benefits for Physician Services Under the Health Insurance Act (September 2011)69

Fee Code Description Tech. Fees ($) Prof. Fees ($) Total Costs ($)
99mTc-SPECT MPI
J866 Myocardial perfusion scintigraphy application of SPECT (maximum 1 per examination) 44.60 31.10 75.7
J813 Studies with ejection fraction 138.60 82.25 220.85
J807 Myocardial perfusion scintigraphy — resting, immediate post-stress 223.15 50.15 273.3
J808 MPI — delayed 82.15 27.45 109.6
G315/G319 Maximal stress ECG 44.60 62.65 107.25
G111/G112 Dipyridamole-thallium stress test 52.05 75.00 127.05
Maintenance fees — from global budget 50.78   50.78
TOTAL 635.93 328.6 964.53
201TI-SPECT MPI
J866 Myocardial perfusion scintigraphy application of SPECT (maximum 1 per examination) 44.60 31.10 75.7
J813 Studies with ejection fraction 138.60 82.25 220.85
J807 Myocardial perfusion scintigraphy — resting, immediate post stress 223.15 50.15 273.3
J808 MPI — delayed 82.15 27.45 109.6
G315/G319 Maximal stress ECG 44.60 62.65 107.25
G111/G112 Dipyridamole-thallium stress test 52.05 75.00 127.05
Maintenance fees — from global budget 50.78   50.78
TOTAL 635.93 328.6 964.53
CTCA
X235 Cardiothoracic CT   155.25 155.25
Technical cost — from global budget 300.00   300.00
Maintenance fees — from global budget 50.78   50.78
TOTAL 350.78 155.25 506.03
Stress Echo
G570/G571 Complete study — 1 and 2 dimensions 76.45 74.10 150.55
G577/G578 Cardiac Doppler study, with or without colour Doppler, in conjunction with complete 1 and 2 dimension Echo studies 45.15 36.90 82.05
G315/G319 Maximal stress ECG 44.60 62.65 107.25
G111/G112 Dipyridamole-thallium stress test 52.05 75.00 127.05
TOTAL 218.25 248.65 466.90
Stress MRI
X441C MRI — thorax — multislice sequence   77.20 77.20
X445C (×3) Repeat (another plane, different pulse sequence — to a maximum of 3 repeats)   38.65 (×3) = 115.95 115.95
X499C 3-D MRI acquisition sequence, including post-processing (minimum of 60 slices; maximum 1 per patient per day)   65.40 65.40
G315/G319 Maximal stress ECG 44.60 62.65 107.25
X486C When cardiac gating is performed (must include application of chest electrodes and ECG interpretation), add 30%   96.36 96.36
Technical cost — from global budget 300.00   300.00
Maintenance fees — from global budget 73.00   73.00
TOTAL 417.60 417.56 835.16
Stress PET
J866 Myocardial perfusion scintigraphy application of SPECT (maximum 1 per examination)   31.10 31.10
J813 Studies with ejection fraction   82.25 82.25
J807 Myocardial perfusion scintigraphy — resting, immediate post-stress   50.15 50.15
J808 MPI — delayed   27.45 27.45
G315/G319 Maximal stress ECG   62.65 62.65
G111/G112 Dipyridamole-thallium stress test   75.00 75.00
Technical cost — from global budget 800.00   800.00
TOTAL 800.00 328.60 1128.60

CT = computed tomography; CTCA = computed tomography coronary angiography; 3-D = three-dimensional; ECG = electrocardiogram; Echo = echocardiogram; MPI = myocardial perfusion imaging; MRI = magnetic resonance imaging; PET = positron emission tomography; Prof. = professional; SPECT = single-photon emission computed tomography; 99mTc = technetium-99m.

Return to Summary Table.

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Appendix 1: Multi-Criteria Decision Analysis Definitions

Domain 1: Criteria Related to the Underlying Health Condition
Criterion Definition
1. Size of the affected population The estimated size of the patient population that is affected by the underlying health condition and which may potentially undergo the test. The ideal measure is point prevalence, or information on how rare or common the health condition is.
2. Timeliness and urgency of test results in planning patient management The timeliness and urgency of obtaining the test results in terms of their impact on the management of the condition and the effective use of health care resources.
3. Impact of not performing a diagnostic imaging test on mortality related to the underlying condition Impact of not performing the test, in whatever way, on the expected mortality of the underlying condition. Measures could include survival curves showing survival over time, and/or survival at specific time intervals with and without the test.
4. Impact of not performing a diagnostic imaging test on morbidity or quality of life related to the underlying condition Impact of not performing the test, in whatever way, on the expected morbidity or on the quality of life reduction of the underlying condition. Measures of impact may include natural morbidity outcome measures such as events or disease severity, or might be expressed using generic or disease-specific quality of life rating scales with and without the test.
Domain 2: Criteria Comparing 99mTc with an Alternative, or Comparing between Clinical Uses
Criterion Definition
5. Relative impact on health disparities Health disparities are defined as situations where there is a disproportionate burden (e.g., incidence, prevalence, morbidity, or mortality) amongst particular population groups (e.g., gender, age, ethnicity, geography, disability, sexual orientation, socioeconomic status, and special health care needs).

Impact on health disparities is assessed by estimating the proportion of current clients of the 99mTc-based test that are in population groups with disproportionate burdens.

(Explanatory note: The implication of this definition is that, everything else being the same, it is preferable to prioritize those clinical uses that have the greatest proportion of clients in groups with disproportionate burdens.)
6. Relative acceptability of the test to patients Acceptability of the 99mTc-based test from the patient's perspective compared with alternatives. Patient acceptability considerations include discomfort associated with the administration of the test, out-of-pocket expenses or travel costs, factors that may cause great inconvenience to patients, as well as other burdens. This criterion does not include risks of adverse events but is about everything related to the experience of undergoing the test.
7. Relative diagnostic accuracy of the test Ability of the test to correctly diagnose the patients who have the condition (sensitivity) and patients who do not have the condition (specificity) compared with alternatives.
8. Relative risks associated with the test Risks associated with the test (e.g., radiation exposure, side effects, adverse events) compared with alternatives. Risks could include immediate safety concerns from a specific test or long-term cumulative safety concerns from repeat testing or exposure.
9. Relative availability of personnel with expertise and experience required for the test Availability of personnel with the appropriate expertise and experience required to proficiently conduct the test and/or interpret the test findings compared with alternatives.
10. Accessibility of alternatives (equipment and wait times) Availability (supply) of equipment and wait times for alternative tests within the geographic area. Includes consideration of the capacity of the system to accommodate increased demand for the alternatives. Excludes any limitation on accessibility related to human resources considerations.
11. Relative cost of the test Operating cost of test (e.g., consumables, heath care professional reimbursement) compared with alternatives.

 

Appendix 2: Literature Search Strategy

OVERVIEW
Interface: Ovid
Databases: Ovid MEDLINE In-Process & Other Non-Indexed Citations, Ovid MEDLINE Daily and Ovid MEDLINE 1946 to Present

EBM Reviews - Cochrane Database of Systematic Reviews

EBM Reviews - Cochrane Central Register of Controlled Trials

EBM Reviews - Database of Abstracts of Reviews of Effects

EBM Reviews - Health Technology Assessment

EBM Reviews - NHS Economic Evaluation Database (NHSEED)

Note: Duplicates between databases were removed in Ovid.
Date of Search: March 7, 2011
Alerts: Monthly search updates began January 14, 2011 and ran until October 2011.
Study Types: Health technology assessments, systematic reviews, meta-analyses, randomized controlled trials, non-randomized studies, and diagnostic accuracy studies.
Limits: Publication years 2001 - March 2011

English language

Humans
SYNTAX GUIDE
/ At the end of a phrase, searches the phrase as a subject heading
MeSH Medical subject heading
.fs Floating subheading
exp Explode a subject heading
* Before a word, indicates that the marked subject heading is a primary topic;

or, after a word, a truncation symbol (wildcard) to retrieve plurals or varying endings
? Truncation symbol for one or no characters only
ADJ Requires words are adjacent to each other (in any order)
ADJ# Adjacency within # number of words (in any order)
.ti Title
.ab Abstract
.hw Heading word: usually includes subject headings and controlled vocabulary 
.tw Text word: searches title, abstract, captions, and full text
.mp Keyword search: includes title, abstract, name of substance word, subject heading word and other text fields
.pt Publication type
.nm Name of substance word: used to search portions of chemical names and includes words from the CAS Registry/EC Number/Name (RN) fields
.jw Journal words: searches words from journal names
/du Diagnostic use
/ri Radionuclide imaging

 

Multi-database Strategy
# Searches
  Filter: randomized controlled trials, non-randomized studies, diagnostic accuracy
1 Randomized Controlled Trial.pt.
2 Controlled Clinical Trial.pt.
3 (Clinical Trial or Clinical Trial, Phase II or Clinical Trial, Phase III or Clinical Trial, Phase IV).pt.
4 Multicenter Study.pt.
5 (random* or sham or placebo*).ti.
6 ((singl* or doubl*) adj (blind* or dumm* or mask*)).ti.
7 ((tripl* or trebl*) adj (blind* or dumm* or mask*)).ti.
8 (control* adj3 (study or studies or trial*)).ti.
9 (non-random* or nonrandom* or quasi-random* or quasirandom*).ti.
10 (allocated adj "to").ti.
11 Cohort Studies/
12 Longitudinal Studies/
13 Prospective Studies/
14 Follow-Up Studies/
15 Retrospective Studies/
16 Case-Control Studies/
17 Cross-Sectional Study/
18 (observational adj3 (study or studies or design or analysis or analyses)).ti.
19 cohort.ti.
20 (prospective adj7 (study or studies or design or analysis or analyses or cohort)).ti.
21 ((follow up or followup) adj7 (study or studies or design or analysis or analyses)).ti.
22 ((longitudinal or longterm or (long adj term)) adj7 (study or studies or design or analysis or analyses or data or cohort)).ti.
23 (retrospective adj7 (study or studies or design or analysis or analyses or cohort or data or review)).ti.
24 ((case adj control) or (case adj comparison) or (case adj controlled)).ti.
25 (case-referent adj3 (study or studies or design or analysis or analyses)).ti.
26 (population adj3 (study or studies or analysis or analyses)).ti.
27 (cross adj sectional adj7 (study or studies or design or research or analysis or analyses or survey or findings)).ti.
28 Comparative Study.pt.
29 (Validation Studies or Evaluation Studies).pt.
30 exp "Sensitivity and Specificity"/
31 False Positive Reactions/
32 False Negative Reactions/
33 "diagnostic use".fs.
34 sensitivit*.tw.
35 (predictive adj4 value*).tw.
36 (distinguish* or differentiat* or enhancement or identif* or detect* or diagnos* or accura* or comparison*).ti,ab.
37 or/1-36
38 37 not case reports.pt.
  Filter: health technology assessments, systematic reviews, meta-analyses
39 meta-analysis.pt.
40 meta-analysis/ or systematic review/ or meta-analysis as topic/ or exp technology assessment, biomedical/
41 ((systematic* adj3 (review* or overview*)) or (methodologic* adj3 (review* or overview*))).ti,ab.
42 ((quantitative adj3 (review* or overview* or synthes*)) or (research adj3 (integrati* or overview*))).ti,ab.
43 ((integrative adj3 (review* or overview*)) or (collaborative adj3 (review* or overview*)) or (pool* adj3 analy*)).ti,ab.
44 (data synthes* or data extraction* or data abstraction*).ti,ab.
45 (handsearch* or hand search*).ti,ab.
46 (mantel haenszel or peto or der simonian or dersimonian or fixed effect* or latin square*).ti,ab.
47 (met analy* or metanaly* or health technology assessment* or HTA or HTAs).ti,ab.
48 (meta regression* or metaregression* or mega regression*).ti,ab.
49 (meta-analy* or metaanaly* or systematic review* or biomedical technology assessment* or bio-medical technology assessment*).mp,hw.
50 (medline or Cochrane or pubmed or medlars).ti,ab,hw.
51 (cochrane or health technology assessment or evidence report).jw.
52 (meta-analysis or systematic review).md.
53 or/39-52
  Radionuclide imaging concept
54 Technetium/
55 exp Technetium Compounds/
56 exp Organotechnetium Compounds/
57 exp Radiopharmaceuticals/
58 (Technetium* or Tc-99 or Tc99 or Tc-99m* or Tc99m* or 99mTc* or 99m-Tc*).tw,nm.
59 Radionuclide Imaging/ or Perfusion Imaging/
60 radioisotope*.mp.
61 ((radionucl* or nuclear or radiotracer*) adj2 (imag* or scan* or test* or diagnos*)).ti,ab.
62 Tomography, Emission-Computed, Single-Photon/
63 (single-photon adj2 emission*).ti,ab.
64 (SPECT or scintigraph* or scintigram* or scintiphotograph*).ti,ab.
65 Radionuclide Ventriculography/
66 Myocardial Perfusion Imaging/
67 (ventriculograph* or perfusion imag*).ti,ab.
68 rMPI.ti,ab.
69 (MPI adj (test* or scan* or screen* or imag*)).ti,ab.
70 (myocardi* adj3 (imag* or tomograph* or scan*)).ti,ab.
71 (Cardiolite or Myoview).ti,ab.
72 (MIBI or sestamibi* or tetrofosmin*).ti,ab.
73 radionuclide imaging.fs.
74 or/54-73
  Preoperative assessment or operative complications concept
75 Preoperative Care/
76 Intraoperative Complications/
77 exp Postoperative Complications/
78 Perioperative care/
79 or/75-78
80 (pre-operative or preoperative or pre-surgery or pre-surgical).ti,ab.
81 (pre-operat* or preoperat* or pre-surgery or presurgery or pre-surgical or presurgical).ti,ab.
82 (operative or perioperative or peri-operative or peroperative or intraoperative or intra-operative or post-operative or postoperative).ti,ab.
83 ((pre or prior or before or peri or post) adj3 (operat* or procedur* or surger*)).ti,ab.
84 (preop or pre-op or periop or peri-op).ti,ab.
85 or/80-84
86 exp Risk Assessment/
87 Risk Factors/
88 (risk* or complications or failure? or death?).ti,ab.
89 ((cardiac or cardiovascular) adj3 (assess* or predict* or evaluat* or estimat* or identif* or screen* or test* or exam* or investigation*)).ti,ab.
90 or/86-89
91 (non-cardiac or noncardiac).ti,ab.
92 (major adj2 (surger* or surgical or operation?)).ti,ab.
93 exp Vascular Surgical Procedures/
94 Aortic Aneurysm, Abdominal/su [Surgery]
95 (vascular surg* or abdominal surg* or intra-abdominal surg* or aortic aneurysm* or aorta aneurysm* or abdominal aneurysm* or aortic surg* or vessel surger* or vascular reconstruct* or vascular repair*).ti,ab.
96 Thoracic Surgical Procedures/
97 ((thoracic or intrathoracic or intraperitoneal) adj3 (surger* or surgical or operation* or procedure*)).ti,ab.
98 or/91-97
99 79 or (85 and 90)
  Results
100 74 and 98 and 99
101 exp animals/
102 exp animal experimentation/
103 exp models animal/
104 exp animal experiment/
105 nonhuman/
106 exp vertebrate/
107 animal.po.
108 or/101-107
109 exp humans/
110 exp human experiment/
111 human.po.
112 or/109-111
113 108 not 112
114 100 not 113
115 limit 114 to english language [Limit not valid in CDSR,ACP Journal Club,DARE,CCTR,CLCMR; records were retained]
116 remove duplicates from 115
117 116 and 38
118 limit 117 to yr="2001 -Current"
119 116 and 53
120 limit 119 to yr="2001-Current"

 

OTHER DATABASES
PubMed
March 8, 2011
Same MeSH, keywords, limits, and study types used as per MEDLINE search, with appropriate syntax used.

 

GREY LITERATURE SEARCHING
Dates for Search: Over the time range February 23 to March 11
Keywords: Included terms for pre-operative cardiac assessment or radionuclide imaging
Limits: Publication years 2001-present

The following sections of the CADTH grey literature checklist, "Grey matters: a practical search tool for evidence-based medicine" (http://www.cadth.ca/en/resources/grey-matters) were searched:

  • Health Technology Assessment Agencies (selected)
  • Clinical Practice Guidelines
  • Databases (free)
  • Internet Search