Implantable Cardioverter-Defibrillator Decision-Making


Indication Overview

Sudden cardiac arrest (SCA) is defined as an abrupt loss of consciousness and unexpected death (sudden cardiac death [SCD]) due to cardiac causes which occurs within one hour of symptom onset.1 SCA is caused by ventricular arrhythmias, which are very rapid heartbeats that can lead to chaotic electrical heart activity resulting in death.2 Eighty percent of SCA is attributed to ventricular tachycardia (VT) and ventricular fibrillation (VF).1 Patients at risk for SCA may receive implantable cardioverter-defibrillators (ICDs). Individuals at the greatest risk for cardiac death are those with left ventricular (LV) dysfunctions. Nuclear imaging helps in determining cardiac blood flow, severity of disease, and therefore the likelihood for SCD from ischemia, which would benefit from revascularization (see ischemia section). Nuclear tests also evaluate LV function, which assists in determining if the patient is likely to benefit from an ICD.3

Population: Patients at risk for SCD who may benefit from an ICD.

Evidence from randomized clinical trials that confirmed the efficacy of ICD for primary and secondary prevention of SCD identified the populations who benefit from ICD. The benefits are restricted to those individuals with severe LV dysfunction as measured by ejection fraction (EF). The Canadian Cardiovascular Society (CCS) has published the following recommendations regarding the implantation of ICDs:4,5

  • Referral for ICD therapy should be considered for patients with ischemic heart disease with or without mild to moderate heart failure symptoms and an LV ejection fraction of ≤ 30%, measured at least one month after myocardial infarction (MI) and at least three months following the coronary revascularization procedure.
  • An ICD may be considered in patients with non-ischemic cardiomyopathy present for at least nine months, New York Heart Association (NYHA) functional class II to III heart failure, and an LV ejection fraction of ≤ to 30% or an LV ejection fraction of 31% to 35%.
  • An ICD may be considered in patients with ischemic heart disease, previous myocardial infarction, LV dysfunction (LV ejection fraction 31% to 35%) measured at least one month after myocardial infarction and three months after coronary revascularization and with inducible ventricular fibrillation/sustained ventricular fibrillation/sustained ventricular tachycardia at electrophysiology study or without an electrophysiology study.
  • An ICD should not be implanted in patients with poor life expectancy due to non-cardiac disease or NYHA class IV heart failure who are not expected to improve with further therapy and who are not candidates for cardiac transplantation.

Intervention: Radionuclide angiography (RNA) cardiac blood pooling imaging using 99mTechnetium (99mTc)-labelled radiotracer or gated single-photon emission computed tomography (SPECT) using 99mTc-labelled radiotracer.

Synonyms for RNA include radionuclide ventriculography, radionuclide cine angiography, gated blood pool, multiple gated acquisition scan, and equilibrium radionuclide angiography. The term RNA will be used throughout this report.

To perform RNA, red blood cells are labelled with 99mTc. Radioactivity is measured with a gamma camera suitably positioned over the patient's chest as the radioactive blood flows through the large vessels and heart. The number of counts recorded at any time is proportional to the amount of blood radioactivity and these counts are proportional to the LV volume.

The two methods used for measurement are first-pass and equilibrium RNA. First-pass RNA measures the radioactivity of only a few beats (usually six to 10) whereas equilibrium RNA accumulates data over a five- to 10-minute period. LV counts at end diastole and at end systole or throughout the cardiac cycle are measured by constructing an LV region of interest (ROI). The measured LV counts within these LV ROIs are corrected for background scatter (BkCorr). The left ventricular ejection fraction (LVEF) = ([BkCorr end-diastolic counts – BkCorr end systolic counts]/BkCorr end-diastolic counts) × 100.6

Comparators: For this report, the following diagnostic tests are considered as alternatives to RNA or 99mTc-labelled radiotracer red blood cell SPECT:

  • Echocardiography (Echo)
  • Magnetic resonance imaging (MRI).

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 Wiley; 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 implantable cardioverter-defibrillators.

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. The search was limited to English language documents. No date limits were applied for the systematic reviews search. For primary studies, the retrieval was limited to documents published between January 1, 2006 and March 23, 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 40 potential clinical articles identified through the meta-analysis/systematic review/health technology assessment (MA/SR/HTA) filtered search and nine were subjected to full-text review. One systematic review and meta-analysis (2002)7 is included in this report.

There were 345 potential articles identified through searching the primary diagnostic accuracy literature, of which 22 were subjected to full-text screening. Four primary studies, comparing RNA to its comparators, were identified in the primary literature search.8-11 Three of the studies8-10 evaluated RNA versus Echo and the fourth, also published in 2010,11compared RNA imaging with MRI in the determination of LVEF.

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 The CCN's national ICD survey identified 29 sites across Canada where ICD implantation is done. Survey responses were received from 25 centres. The 25 centres indicated an annual ICD implant rate of 4,284 new and 1,582 replacement, for a total of 5,866 (Dan Purdham, Cardiac Care Network of Ontario; personal communication, February 23, 2012). The population of Canada in 2010 was 34,126,200, which indicates that more than 1.7 per 10,000 Canadians received ICDs that year.

Given these estimates, and the understanding that cardiac imaging is conducted in order to determine eligibility for ICD implantation, the size of the affected population is estimated 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 According to the Wait Time Alliance, cardiac nuclear imaging for the evaluation of LV function should be performed within 24 hours for an emergency case (immediate danger to life, required for therapeutic management), within three days for urgent cases (situation is unstable and has the potential to deteriorate quickly and result in an emergency admission), or within 14 days for scheduled cases (situation involving minimal pain, dysfunction, or disability — also called "routine" or "elective").12

For ICD decision-making purposes, the underlying condition has a significant 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 If the imaging test is not performed and the ICD-eligible patient does not receive an ICD, sudden death may occur.13 Although no evidence was identified by the literature search to directly address this criterion, it is assumed that diagnostic imaging test results can have significant impact on mortality.
4 Impact of not performing a diagnostic imaging test on morbidity or quality of life related to the underlying condition If the imaging test is not done and the ICD-ineligible patient (LVEF is not less 35%) receives empirical ICD therapy, the patient is put at risk for ICD complications.4  These complications include lead dislodgement, ICD system infection, pneumothorax, device malfunction, serious bleeding, venous thrombosis, and cardiac perforation.4

Diagnostic imaging test results can have minimal impact on morbidity and 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 No information regarding acceptability of RNA by the patient was identified; however, with the assumption that the test is similar to other nuclear medicine tests, RNA is likely to be well-accepted. Patients may have concerns about radiation exposure and the intravenous injection of a radiopharmaceutical agent.

Echo is likely to be well tolerated by patients. Echo may be preferred by some patients, as there is no radiation exposure with it.  

Because of the closed space of 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.14,15 Some patients may have difficulty remaining still during the scan. Patients are not exposed to radiation during an MRI scan, which may be more acceptable to some.

RNA imaging with 99mTc radiolabelled tracers is:
  • minimally less acceptable than Echo
  • minimally less acceptable than MRI.
7 Relative diagnostic accuracy of the test A 2002 meta-analysis by Ioannidis et al.7 concluded that ECG-gated SPECT correlates well with cardiac MRI for measurement of LV volumes and EF. A 2010 primary study by Harel et al.11 found that RNA provides good estimates of LVEF when compared with MRI as the gold standard.

Three primary studies, published in 2010, evaluated 99mTc-RNA versus Echo. Lane et al.8 intended to determine whether current screening techniques can identify patients who are deemed to be appropriate for ICD implantation. With Echo examined as the screening technique and RNA as the gold standard, the authors found the sensitivity of Echo for predicting an RNA LVEF < 30% to be 84.4% (specificity: 55.1%). Müller et al.9 measured LVEF using real time 3-D Echo in a subset of patients with severe systolic dysfunction. Again, RNA was used as the reference standard. The correlation between Echo and RNA was described as modest (r = 0.49). Hutyra et al.10 used gated cardiac SPECT as the reference standard in their evaluation of Echo. The correlation between the two modalities varied from 0.71 for monoplanar Echo to 0.88 for triplanar Echo.

Based on the evidence available, the diagnostic accuracy of RNA imaging with 99mTc radiolabelled tracers:
  • is minimally better than Echo
  • has a similar diagnostic accuracy as MRI.
8 Relative risks associated with the test Non–radiation-related risks

No information was identified regarding the non–radiation-related risks for patients undergoing RNA.

No risks associated with Echo were identified.

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.16 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 range are also rare (0.004% to 0.7%).17

Radiation-related Risks

Patients undergoing RNA are exposed to a radiation dose of 6.2 mSv.18 The comparators (Echo and MRI) do not expose the patient to ionizing radiation.

Overall, RNA:
  • is minimally less safe than Echo
  • is minimally less safe than MRI.
9 Relative availability of personnel with expertise and experience required for the test Expertise: Sensitivity, specificity, and reproducibility of LVEF measures by Echo are strongly influenced by interobserver variability, whereas RNA is not.

Personnel: In Canada, physicians involved in the performance, supervision, and interpretation of diagnostic nuclear imaging, MRI, and U/S should be diagnostic radiologists or nuclear medical physicians. According to the CMA, there are 1,149 practicing cardiologists in Canada (CMA, 2011). Not all radiologists, nuclear medical physicians, nuclear cardiologists, or cardiologists have the expertise to conduct 99mTc-RNA 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 imaging using RNA is not available it is assumed that:
  • more than 95% of the procedures can be performed in a timely manner using Echo
  • 25-74% of the procedures can be performed in a timely manner using MRI.
10 Accessibility of alternative tests (equipment and wait times) Nuclear medicine facilities with gamma cameras are required for RNA. As of January 1, 2007, there was an average of 18.4 nuclear medicine cameras per million people, with none available in the Yukon, Northwest Territories, or Nunavut.19 SPECT/CT scanners were available in only five jurisdictions at that time: New Brunswick, Quebec, Ontario, Saskatchewan, and British Columbia.19

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

As of January 1, 2007, there were 6.8 MRI devices per million population in Canada, with no MRI scanners available in the Yukon, Northwest Territories, or Nunavut.19 According to the CIHI 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.19 In 2010, the average wait time for MRI in Canada was 9.8 weeks.20

Assuming the necessary expertise is available, if 99mTc imaging using RNA is not available it is estimated that:
  • more than 95% of the procedures can be performed in a timely manner using Echo
  • 25-74% of the procedures can be performed in a timely manner using MRI.
11 Relative cost of the test

According to our estimates, the cost of RNA with 99mTc-based radioisotopes is $330.40. Echo is a minimally less costly alternative, whereas MRI is moderately more costly than RNA with 99mTc-based radioisotopes.

Relative Costs
Test Total Costs ($) Cost of Test Relative to 99mTc-Based Test ($)
RNA 330.40 Reference
Echo 150.55 -179.85
MRI 759.29 +428.89

 

CCN = Cardiac Care Network; CCS = Canadian Cardiovascular Society; CIHI = Canadian Institute for Health Information; CT = computed tomography; 3-D = three-dimensional; ECG = electrocardiography; Echo = echocardiography; EF = ejection fraction; Gd = gadolinium; ICD = implantable cardioverter-defibrillator; LV = left ventricular; LVEF = left ventricular ejection fraction; MRI = magnetic resonance imaging; mSv = millisievert;PEI = Prince Edward Island; r = correlation coefficient; RNA = radionuclide angiography; SPECT = single-photon emission computed tomography; 99mTc = 99mTechnetium; U/S = ultrasound.

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

The Cardiac Care Network of Ontario's national ICD survey identified 29 sites across Canada where ICD implantation is done. Survey responses were received from 25 centres. The 25 centres indicated an annual ICD implant rate of 4,284 new and 1,582 replacement, for a total of 5,866 (Dan Purdham, Cardiac Care Network of Ontario; personal communication, February 23, 2012). The population of Canada in 2010 was 34,126,200, which indicates that more than 1.7 per 10,000 Canadians received ICDs that year.

Given these estimates, and the understanding that cardiac imaging is conducted in order to determine eligibility for ICD implantation, the size of the affected population is estimated to be more than 1 in 10,000 (0.01%) and less than 1 in 1,000 (0.1%).

Return to Summary Table.

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

According to the Wait Time Alliance, cardiac nuclear imaging for the evaluation of LV function should be performed within 24 hours for an emergency case (immediate danger to life, required for therapeutic management), within three days for urgent cases (situation is unstable and has the potential to deteriorate quickly and result in an emergency admission), or within 14 days for scheduled cases (situation involving minimal pain, dysfunction, or disability — also called "routine" or "elective").12

For ICD decision-making purposes, the underlying condition has a significant impact on the management of the condition and the effective use of health care resources.

Return to Summary Table.

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

Although no evidence was identified by the literature search to directly address this criterion, the assumption would be that patients who received an ICD would have lower mortality rates than those patients with similar cardiac functioning who did not receive an ICD. Patients with an LVEF less than 35% and previous occurrence of VF have the greatest benefit of reduced mortality from an ICD.4 For primary prevention in high-risk patients with no previous occurrence of VF, the benefit is seen when LVEF is low (less than 30%).4

Return to Summary Table

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

If the test is not done and the patient is not considered for an ICD, they may suffer SCD.13

If the test is not done and the patient receives an ICD based on clinical parameters, or empirically (and the LVEF is not less 35%), the patient has the potential of not achieving any clinical benefit from the ICD and may be exposed to potential complications. These complications include lead dislodgement, ICD system infection, pneumothorax, device malfunction, serious bleeding, venous thrombosis, and cardiac perforation.4 In addition, some ICD recipients will experience inappropriate shocks.4 The occurrence of any shocks compared to no shocks is independently associated with statistically significant reductions (P < 0.05) in mental well-being and physical functioning in patients who received an ICD.21

Return to Summary Table.

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

To be scored locally.

Return to Summary Table.

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

RNA
No information regarding the acceptability of RNA by the patient was identified; however, with the assumption that the test is similar to other nuclear medicine tests, RNA is likely to be well- accepted. Patients may have concerns about radiation exposure and the intravenous injection of a radiopharmaceutical agent.

Echo
This test is likely to be well-tolerated by patients. Echo may be preferred by some patients, as there is no radiation exposure.

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 (Medical Isotopes and Imaging Modalities Advisory Committee [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.14,15 Some patients may have difficulty remaining still during the scan. Patients are not exposed to radiation during an MRI scan, which may be more acceptable to some.

Return to Summary Table.

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

Systematic reviews and meta-analyses
One systematic review and meta-analysis (2002)7 was identified in this report's meta-analysis/systematic review/health technology assessment (MA/SR/HTA).

99mTc-SPECT compared with MRI
Ioannidis et al. (2002)7 performed a meta-analysis of all available data comparing electrocardiography(ECG)-gated SPECT with cardiac MRI in terms of the accurate assessment of LV and end-diastolic volumes, end-systolic volume, and EF. Data were eligible regardless of whether they referred to healthy subjects, patients with suspected or proven disease, and regardless of whether the SPECT images were captured at rest or after stress. All technical parameters and algorithms used for LV volumes and EF calculations were included. Only the 99mTc data were pooled in the analysis.

Nine studies were included in the analysis (164 subjects who had both a 99mTc-SPECT and MRI scan). Study populations included: known or suspected coronary artery disease (n = 5), post-MI (n = 1), post-coronary artery bypass grafting (n = 1), normal EF (n = 1), EF < 40% (n = 1), mixed (SPECT referrals, n = 1). All studies used rest acquisitions. Seven studies reported that test interpretation was blinded to the results of the other test. Sensitivity and specificity were calculated for each study and pooled using simple pooling techniques. In cases of significant heterogeneity, random effects analysis was used (Table 2).

Table 2: Diagnostic Accuracy Characteristics for EF Measurements of 99mTc-SPECT Using MRI as the Gold Standard

Simple Pooling for Detecting EF ≤ 40%
Sensitivity 91% (95% CI, 80% to 97%)
Specificity 88% (95% CI, 80% to 93%)
Random Effects Pooling for Detecting EF ≤ 40%
Sensitivity 83% (95% CI, 69% to 92%)
Specificity 84% (95% CI, 75% to 90%)
Overall correlation coefficient 0.90, P < 0.001
Discrepancies Between EF Measures
≥ 5% 52% (95% CI, 37% to 63%)
≥ 10% 23% (95% CI, 11% to 42%)

CI= confidence interval; EF = ejection fraction; MRI = magnetic resonance imaging; MRI = magnetic resonance imaging; 99mTc-SPECT = 99mtechnetium-single photon emission computed tomography.

Primary Studies

Four primary studies comparing RNA to its comparators were identified in the primary literature search.8-11 Three of the studies8-10 evaluated RNA versus Echo and the fourth, also published in 2010,11 compared RNA imaging to MRI in the determination of LVEF.

99mTc-RNA versus Echo
An important Canadian study by Lane et al. (2010)8 examined the usefulness of current screening techniques using Echo to identify patients who should receive a primary prophylactic ICD. Two-hundred and forty-one patients, seen for consideration for a primary prophylactic defibrillator and referred for both Echo and RNA, were included in the analysis.8 The screening Echo used semi-quantitative or quantitative methods to measure the LVEF.8 In Table 3 and 3A, Echo grade 3 refers to LVEF of 20% to 39%, and Echo grade 4 refers to LVEF of < 20%.8 The study authors concluded that Echo and RNA are not equivalent modalities for measuring LVEF.8

Table 3: Semi-quantitative Echo Diagnostic Criteria for Screening LVEF8

Echo Grade Sensitivity (%) Specificity (%) Positive Likelihood Ratio Negative Likelihood Ratio Positive Predictive Value (%) Negative Predictive Value (%)
RNA LVEF < 30%
4 40.9 85.5 2.83 0.69 78.9 52.2
3 to 4 or worse 58.2 65.1 1.67 0.64 68.8 54.0
3 or worse 95.5 21.7 1.22 0.21 61.8 78.3
RNA LVEF < 35%
4 34.6 90.0 3.46 0.73 93.0 26.5
3 to 4 or worse 52.9 70.0 1.76 0.67 87.1 28.0
3 or worse 92.8 30.0 1.33 0.24 83.5 52.2

Echo = echocardiography; LVEF = left ventricular ejection fraction; RNA = radionuclide angiography.

Table 3A: Quantitative Echo for Screening LVEF8

  Sensitivity (%) Specificity (%) Positive Likelihood Ratio Negative Likelihood Ratio
RNA LVEF < 30% 84.4 55.1 1.88 0.28
RNA LVEF < 35% 88.7 48.2 1.71 0.23

Echo = echocardiography; LVEF= left ventricular ejection fraction; RNA= radionuclide angiography.

Müller et al. (2010)9 compared LVEF measures between RNA and three-dimensional (3-D) Echo. Consecutive patients sent to their facility with an LVEF < 35% measured visually by two- dimensional Echo underwent a full-volume 3-D Echo and an RNA one week later. All images were interpreted blindly. Fifty patients were enrolled: 58% with ischemic heart disease, and 42% with dilated cardiomyopathy. Only 38 patients (76%) had Echo images of sufficient quality for evaluation. The study authors concluded that RNA and 3-D Echo are not interchangeable for LVEF measures in patients with severely depressed systolic function.

Table 4: LVEF measures for 3-D Echo and RNA

  Mean LVEF (SD) Mean Difference (SD)
(Echo — RNA)
Agreement (95% limits)
RNA 3-D Echo
All patients (n = 50) 0.27 (0.09) 0.20 (0.07)* –0.07 (0.09) –0.24 to 0.10
Only good quality images (n = 38) 0.27 (0.08) 0.21 (0.07)* –0.05 (0.07) –0.20 to 0.09

3-D = three-dimensional; Echo = echocardiography; LVEF = left ventricular ejection fraction; RNA = angiography; SD = standard deviation
*=statistically significantly smaller values, p<0.001

In a 2010 publication by Hutyra et al., a cohort (n = 70) of ischemic cardiomyopathy patients underwent both Echo (monoplane and two-dimensional) and 99mTc sestamibi-labelled SPECT scans to measure LVEF.10 SPECT scans were followed by Echo one hour later. 99mTc-SPECT EFs were obtained using software. Single-measured Echo parameters were triplanar, biplanar, and monoplanar, and images were interpreted blindly. Patients with ischemic cardiomyopathy indicated for cardiosurgical revascularization based on coronarography were evaluated. All patients were New York Heart Association (NYHA) I-III and 65% had verified LV systolic dysfunction defined by LVEF < 50%. As indicated in Table 5, 99mTc-SPECT and Echo LVEF measurements were significantly correlated, with the best agreement seen with triplanar Echo. The study authors concluded that, for a one-time measurement, two-dimensional Echo using the triplanar analysis is interchangeable with 99mTc-SPECT.

Table 5: Diagnostic Parameters of Echo and SPECT10

Scan LVEF (SD) Median LVEF diff (95% CI) Correlation Coefficient Agreement (95% Lower & Upper Limits)
99mTc-SPECT 36.6% (11.5%) Reference Reference N/A
Echo –monoplanar 36.6% (12.2%) 0.1% (–1.9 to –2.1) 0.71* –0.8% (–17.2 to 17.3)
Echo – biplanar 35.7% (10.0%) 0.7% (–0.5 to –2.5) 0.83* –0.7% (–13.4 to 11.7)
Echo – triplanar 35.9% (10.0) 0.4% (–0.7 to –1.7) 0.88* –0.4% (–11.7 to 10.7)

CI = confidence interval; diff = difference; Echo = echocardiography; LVEF = left ventricular ejection fraction; N/A = not applicable; SD = standard deviation; SPECT = single-photon emission computed tomography; 99mTc-SPECT = 99mtechnetium single-photon emission computed tomography.
*P value < 0.001.

99mTc-RNA versus MRI
Harel et al.11 evaluated the use of a radionuclide-gated blood pool SPECT algorithm and cardiac MRI, with a study population of 55 patients. The mean delay between the two imaging tests was 12 ± 10 days. The mean LVEF estimates estimated by the different imaging modalities and algorithms are provided in Table 6. LVEFs calculated with planar, MHIspace, and QBSspace methods were correlated with LVEF values obtained by cardiac MRI. Count-based algorithms provided increased correlation. The authors concluded that RNA provided good estimates of LVEF when compared to cardiac MRI as the gold standard.

Table 6: Left Ventricular Ejection Fraction (LVEF) Estimates

Test Mean LVEF ± SD (%) Correlation Coefficient
cMRI (gold standard) 39 ±13 n/a
Planar RNA 40 ± 13 0.81
MHIspace 43 ± 12 0.82
QBSspace 39 ± 14 0.82
MHIcount 42 ± 13 0.88
QBScount 46 ± 15 0.84

cMRI = cardiac magnetic resonance imaging; LVEF = left ventricular ejection fraction; MHI = Montreal Heart Institute blood-pool software; QBS = quantitative blood-pool software (Cedar-Sinai); RNA = radionuclide angiography; SD = standard deviation.

Return to Summary Table.

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

Non–radiation-related Risks

RNA
No information was identified regarding non–radiation-related risks for patients.

Echo
Three relatively large studies — with sample sizes of 42,408 patients (2009),22 26,774 patients (2009),23 and 5069 patients (2008)24 — 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 that of patients who received no contrast. No additional risks associated with Echo were identified.

MRI
MRI is contraindicated in patients with metallic implants including pacemakers.25 MRI is often used in conjunction with the contrast agent gadolinium (Gd). Some patients may experience an allergic reaction to the contrast agent (if required), which may worsen with repeated exposure.16 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,17 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%.17

Radiation-related Risks

Among the modalities to assess chemotherapy-induced cardiotoxicity, RNA is the only one to expose the patient to ionizing radiation. The average effective dose of radiation delivered with each of these procedures can be found in Table 7.

Table 7: Effective Radiation Doses for Various Imaging Tests

Test Effective Radiation Dose (mSv)
RNA 6.218
Average background dose of radiation per year 1 to 3.026-28

mSv = millisievert ; RNA = radionuclide angiography.

Return to Summary Table.

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

The personnel required for the performance of the imaging tests to make decisions regarding ICD implantation are presented by imaging modality. A summary of the availability of personnel required for ICD decision-making, by RNA or any of the alternative imaging modalities, is provided in Table 8.

RNA
In Canada, physicians involved in the performance, supervision, and interpretation of cardiac nuclear imaging (specifically RNA using 99mTc-labelled radiotracer) should be nuclear medicine physicians with particular expertise in nuclear cardiology. In some jurisdictions, cardiologists also provide much of the nuclear cardiology services. According to the Canadian Medical Association (CMA), there are 1,149 practising cardiologists in Canada (CMA, 2011).

Nuclear medicine technologists are required to conduct RNA scans. Technologists must be certified by the Canadian Association of Medical Radiation Technologists (CAMRT) or an equivalent licensing body.

All alternative imaging modalities
In Canada, physicians involved in the performance, supervision, and interpretation of diagnostic CT scans, MRI, and ultrasound should be diagnostic radiologists19 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 are also qualified if they are certified by a recognized certifying body and hold a valid provincial licence.29 According to the CMA, there are 1,149 practising cardiologists in Canada (CMA, 2011).

Medical radiation technologists must be certified by CAMRT or an equivalent licensing body. 

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, MRI scanners, and nuclear medicine equipment.29

Echo
Echocardiography 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 practising cardiologists in Canada (CMA, 2011). 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 (CARDUP). They should be members of their national or provincial professional organization. Sonography specialties include general sonography, vascular sonography, and cardiac sonography.19 In Quebec, sonographers and medical radiation technologists are grouped together; in the rest of Canada, sonographers are considered a distinct professional group.19

MRI
Medical technologists must have CAMRT certification in magnetic resonance imaging or be certified by an equivalent licensing body recognized by CAMRT.

Table 8: Medical Imaging Professionals in Canada, 200619

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 9 provides an overview of the availability of equipment required to make decisions regarding ICD implantation. Data for nuclear medicine cameras (including SPECT) are current to January 1, 2007. The number of MRI and SPECT/CT scanners is current to January 1, 2010. Data were not available for Echo.

Table 9: Diagnostic Imaging Equipment in Canada19,30

  Nuclear Medicine Cameras MRI Scanners SPECT/CT Scanners
Number of devices19,30 60319 21830 9630
Average number of hours of operation per week (2006-2007)19 40 71 n/a
Provinces and Territories with no devices available YT, NT, NU YT, NT, NU PEI, YT, NT, NU

CT = computed tomography; MRI = magnetic resonance imaging; NT = Northwest Territories; NU = Nunavut; PEI = Prince Edward Island; SPECT = single-photon emission computed tomography; YT = Yukon.

RNA
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.19

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.30 According to the 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 PEI to 99 hours in Ontario, with a national average of 71 hours.19 In 2010, the average wait time for MRI in Canada was 9.8 weeks.20

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 RNA 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; these estimates 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 10), the cost of RNA with 99mTc-based radioisotopes is $330.40. Echo is a minimally less costly alternative, whereas MRI is moderately more costly than RNA with 99mTc-based radioisotopes.

Table 10: Cost Estimates Based on the Ontario Schedule of Benefits for Physician Services Under the Health Insurance Act (September 2011)31

Fee Code Description Tech. Fees ($) Prof. Fees ($) Total Costs ($)
RNA
J813 Myocardial wall motion — studies with ejection fraction 138.60 82.25 220.85
J866 Application of SPECT (maximum 1 per examination) 44.60 31.10 75.70
Maintenance fees — from global budget 33.85   33.85
TOTAL 217.05 113.35 330.40 
Echo
G570/G571 Complete study — 1 and 2 dimensions 76.45 74.10 150.55
TOTAL 76.45 74.10 150.55 
MRI
X441C MRI — thorax — multislice sequence   77.20 115.85
X445C (×3) Repeat (another plane, different pulse sequence — to a maximum of 3 repeats)   38.65 (×3) = 115.95 115.95
X499 3-D MRI acquisition sequence, including post-processing (minimum of 60 slices; maximum 1 per patient per day)   65.40 65.40
X487 When gadolinium is used   38.60 38.60
X486 When cardiac gating is performed (must include application of chest electrodes and ECG interpretation), add 30%   89.14 89.14
Technical cost — from global budget 300.00   300.00
Maintenance fees — from global budget 73.00   73.00
TOTAL 373.00 386.29 759.29

3-D = three-dimensional; ECG = electrocardiogram; Echo = echocardiogram; MRI = magnetic resonance imaging; prof. = professional; RNA = radionuclide angiogram; SPECT = single-photon emission computed tomography; tech. = technical.

Return to Summary Table

References

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  16. Siddiqi NH. Contrast medium reactions. 2011 Apr 20 [cited 2011 Oct 5]. In: Medscape reference [Internet]. New York: WebMD; c1994 - . Available from: http://emedicine.medscape.com/article/422855-overview.
  17. ACR Committee on Drugs and Contrast Media. ACR manual on contrast media [Internet]. Version 7. Reston (VA): American College of Radiology; 2010. [cited 2011 Oct 5]. Available from: http://www.acr.org/SecondaryMainMenuCategories/quality_safety/contrast_manual/FullManual.aspx
  18. Danias PG, Heller GV. Noninvasive methods for measurement of left ventricular systolic function. 2009 Nov 24 [cited 2011 Jul 8]. In: UpToDate [Internet]. Version 19.1. Waltham (MA): UpToDate; c2005 - . Available from: http://www.uptodate.com Subscription required.
  19. Canadian Institute for Health Information. Medical imaging in Canada 2007 [Internet]. Ottawa: The Institute; 2008. 199 p. [cited 2011 Apr 12]. Available from: http://secure.cihi.ca/cihiweb/products/MIT_2007_e.pdf
  20. Barua B, Rovere M, Skinner BJ. Waiting your turn: wait times for health care in Canada [Internet]. 20th ed. Vancouver (BC): Fraser Institute; 2010 Dec. 90 p. [cited 2011 Apr 15]. (Studies in health care policy). Available from: http://www.fraserinstitute.org/uploadedFiles/fraser-ca/Content/research-news/research/publications/waiting-your-turn-2010.pdf
  21. Schron EB, Exner DV, Yao Q, Jenkins LS, Steinberg JS, Cook JR, et al. Quality of life in the antiarrhythmics versus implantable defibrillators trial: impact of therapy and influence of adverse symptoms and defibrillator shocks. Circulation. 2002 Feb 5;105(5):589-94.
  22. Dolan MS, Gala SS, Dodla S, Abdelmoneim SS, Xie F, Cloutier D, et al. Safety and efficacy of commercially available ultrasound contrast agents for rest and stress echocardiography a multicenter experience. J Am Coll Cardiol. 2009 Jan 6;53(1):32-8.
  23. Abdelmoneim SS, Bernier M, Scott CG, Dhoble A, Ness SA, Hagen ME, et al. Safety of contrast agent use during stress echocardiography: a 4-year experience from a single-center cohort study of 26,774 patients. JACC Cardiovasc Imaging. 2009 Sep;2(9):1048-56.
  24. Shaikh K, Chang SM, Peterson L, Rosendahl-Garcia K, Quinones MA, Nagueh SF, et al. Safety of contrast administration for endocardial enhancement during stress echocardiography compared with noncontrast stress. Am J Cardiol. 2008 Dec 1;102(11):1444-50.
  25. College of Physicians and Surgeons of Ontario. Independent health facilities: clinical practice parameters and facility standards; magnetic resonance imaging [Internet]. 2nd ed. Toronto: The College; 2009. [cited 2011 Jun 13; revised 2010 Apr]. Available from: http://www.cpso.on.ca/uploadedFiles/policies/guidelines/facilties/MagneticRI.pdf
  26. Canadian Nuclear Safety Commission. Radioactive release data from Canadian nuclear power plants 1999-2008 [Internet]. Ottawa: CNSC; 2009 Sep. Report No.: INFO-0210/Rev. 13. [cited 2011 Sep 13]. Available from: http://nuclearsafety.gc.ca/pubs_catalogue/uploads/INFO0210_R13_e.pdf
  27. Grasty RL, LaMarre JR. The annual effective dose from natural sources of ionising radiation in Canada. Radiat Prot Dosimetry. 2004;108(3):215-26.
  28. Mettler FA, Huda W, Yoshizumi TT, Mahesh M. Effective doses in radiology and diagnostic nuclear medicine: a catalog. Radiology [Internet]. 2008 Jul [cited 2011 Jun 13];248(1):254-63. Available from: http://radiology.rsna.org/content/248/1/254.long
  29. Royal College of Physicians and Surgeons of Canada. Objectives of training in nuclear medicine [Internet]. Ottawa: The College; 2009. [cited 2011 Jun 13]. Available from: http://rcpsc.medical.org/residency/certification/objectives/nucmed_e.pdf
  30. Canadian Institute for Health Information (CIHI). Selected medical imaging equipment in Canada [Internet]. Ottawa: The Institute; 2010 Jan 1. Report No.: MI5. [cited 2011 Jun 29]. Available from: http://apps.cihi.ca/MicroStrategy/asp/Main.aspx?server=torapprd30.cihi.ca&project=Quick+Stats&uid=pce_pub_en&pwd=&evt=2048001&visualizationMode=0&documentID=50A7B0D5472B6AE40A9AE7AA062D42EC Source: National Survey of Selected Medical Imaging Equipment, CIHI, 2010.
  31. Ontario Ministry of Health and Long-Term Care. Schedule of benefits for physician services under the Health Insurance Act: effective September 1, 2011 [Internet]. Toronto: OMHLTC; 2011. [cited 2011 Oct 5]. Available from: http://www.health.gov.on.ca/english/providers/program/ohip/sob/physserv/physserv_mn.html

 

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 March 23, 2011>
Date of Search: March 23, 2011
Alerts: Monthly search updates began March 23, 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: English language

No date limits for systematic reviews

Publication years 2006-2011 for primary studies
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
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
1 Defibrillators, Implantable/
2 ((Implant* or internal) adj5 (defibrillator* or cardioverter* or cardioversion)).ti,ab.
3 (ICD or ICDs).ti,ab.
4 Ventricular Dysfunction, Left/ri
5 or/1-4
6 Ventricular Dysfunction, Left/
7 (left ventricular ejection fraction or LVEF or left ventricular dysfunction).ti,ab.
8 1 or 2 or 3 or 6 or 7
9 Technetium/
10 exp Technetium Compounds/
11 exp Organotechnetium Compounds/
12 exp Radiopharmaceuticals/
13 (Technetium* or Tc-99* or Tc99* or Tc-99m* or Tc99m* or 99mTc* or 99m-Tc*).tw,nm.
14 Radionuclide Imaging/ or Perfusion Imaging/
15 radionuclide imaging.fs.
16 radioisotope*.mp.
17 ((radionucl* or nuclear or radiotracer*) adj2 (imag* or scan* or test* or diagnos*)).ti,ab.
18 exp Tomography, Emission-Computed, Single-Photon/
19 (single-photon adj2 emission*).ti,ab.
20 (SPECT or scintigraph* or scintigram* or scintiphotograph*).ti,ab.
21 exp Tomography, Emission-Computed, Single-Photon/
22 Radionuclide Angiography/
23 exp Radionuclide Ventriculography/ or Gated Blood-Pool Imaging/ or Cardiac-Gated Imaging Techniques/
24 ((gated or gate) adj2 (blood pool or acquisition)).ti,ab.
25 RNA.ti,ab.
26 ((radionuclide or nuclear) adj2 (ventriculograph* or angiograph* or angiocardiograph*)).ti,ab.
27 (RNA or RNCA or ERNA).ti,ab.
28 or/9-27
29 meta-analysis.pt.
30 meta-analysis/ or systematic review/ or meta-analysis as topic/ or exp technology assessment, biomedical/
31 ((systematic* adj3 (review* or overview*)) or (methodologic* adj3 (review* or overview*))).ti,ab.
32 ((quantitative adj3 (review* or overview* or synthes*)) or (research adj3 (integrati* or overview*))).ti,ab.
33 ((integrative adj3 (review* or overview*)) or (collaborative adj3 (review* or overview*)) or (pool* adj3 analy*)).ti,ab.
34 (data synthes* or data extraction* or data abstraction*).ti,ab.
35 (handsearch* or hand search*).ti,ab.
36 (mantel haenszel or peto or der simonian or dersimonian or fixed effect* or latin square*).ti,ab.
37 (met analy* or metanaly* or health technology assessment* or HTA or HTAs).ti,ab.
38 (meta regression* or metaregression* or mega regression*).ti,ab.
39 (meta-analy* or metaanaly* or systematic review* or biomedical technology assessment* or bio-medical technology assessment*).mp,hw.
40 (medline or Cochrane or pubmed or medlars).ti,ab,hw.
41 (cochrane or health technology assessment or evidence report).jw.
42 or/29-41
43 8 and 28 and 42
44 43
45 limit 44 to english language
46 exp "Sensitivity and Specificity"/
47 False Positive Reactions/
48 False Negative Reactions/
49 du.fs.
50 sensitivit*.tw.
51 (distinguish* or differentiat* or enhancement or identif* or detect* or diagnos* or accura* or comparison*).ti,ab.
52 (predictive adj4 value*).tw.
53 Comparative Study.pt.
54 (Validation Studies or Evaluation Studies).pt.
55 Randomized Controlled Trial.pt.
56 Controlled Clinical Trial.pt.
57 (Clinical Trial or Clinical Trial, Phase II or Clinical Trial, Phase III or Clinical Trial, Phase IV).pt.
58 Multicenter Study.pt.
59 (random* or sham or placebo*).ti.
60 ((singl* or doubl*) adj (blind* or dumm* or mask*)).ti.
61 ((tripl* or trebl*) adj (blind* or dumm* or mask*)).ti.
62 (control* adj3 (study or studies or trial*)).ti.
63 (non-random* or nonrandom* or quasi-random* or quasirandom*).ti.
64 (allocated adj "to").ti,ab.
65 Cohort Studies/
66 Longitudinal Studies/
67 Prospective Studies/
68 Follow-Up Studies/
69 Retrospective Studies/
70 Case-Control Studies/
71 Cross-Sectional Study/
72 (observational adj3 (study or studies or design or analysis or analyses)).ti.
73 cohort.ti.
74 (prospective adj7 (study or studies or design or analysis or analyses or cohort)).ti.
75 ((follow up or followup) adj7 (study or studies or design or analysis or analyses)).ti.
76 ((longitudinal or longterm or (long adj term)) adj7 (study or studies or design or analysis or analyses or data or cohort)).ti.
77 (retrospective adj7 (study or studies or design or analysis or analyses or cohort or data or review)).ti.
78 ((case adj control) or (case adj comparison) or (case adj controlled)).ti.
79 (case-referent adj3 (study or studies or design or analysis or analyses)).ti.
80 (population adj3 (study or studies or analysis or analyses)).ti.
81 (cross adj sectional adj7 (study or studies or design or research or analysis or analyses or survey or findings)).ti.
82 or/46-81
83 82 not case reports.pt.
84 5 and 28 and 83
85 84
86 limit 85 to (english language and yr="2006 -Current")

 

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

Cochrane Library
Issue 3, 2011

Same MeSH, keywords, and date limits used as per MEDLINE search, excluding study types and Human restrictions. Syntax adjusted for Cochrane Library databases.

 

GREY LITERATURE SEARCHING
Dates for Search: March 21-25, 2011
Keywords: Included terms for implantable cardioverter-defibrillators and radionuclide imaging
Limits: English language

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