Survival of Patients Receiving a Primary Prevention Implantable Cardioverter-Defibrillator in Clinical Practice vs Clinical Trials

Jan 02, 2013
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Authors:
Al-Khatib SM, Hellkamp A, Bardy GH, et al.
Citation:
JAMA 2013;309:55-62.
Summary By:
Fred Morady, MD, FACC

Study Questions:

Are the results of primary prevention implantable cardioverter-defibrillator (ICD) trials applicable to clinical practice?

Methods:

A national ICD registry was queried to identify patients who received an ICD for primary prevention of sudden death (SD) and who met MADIT-II criteria (prior myocardial infarction, left ventricular ejection fraction [LVEF] ≤30%) or SCD-HeFT criteria (ischemic or nonischemic cardiomyopathy, class II-III heart failure, LVEF ≤35%). The endpoint of the study was all-cause mortality.

Results:

A total of 28,608 patients who met the MADIT-II criteria and 53,351 patients who met the SCD-HeFT criteria were identified in the ICD registry. Compared to the 742 patients in MADIT-II and 829 patients in SCD-HeFT who received an ICD, the corresponding registry patients were older by a mean of 2-7 years and had more comorbidities. The median durations of follow-up in the MADIT-II, SCD-HeFT, and registry patients were 19.5, 46, and 35 months, respectively. After adjustment for confounding variables, there was no significant difference in 2-year mortality between the MADIT-II patients (15.6%) and corresponding registry patients (13.9%) or in 3-year mortality between the SCD-HeFT patients (17.4%) and corresponding registry patients (17.3%).

Conclusions:

Survival in patients who receive an ICD for primary prevention of SD in a clinical practice setting does not differ significantly from that of similar subjects who received an ICD in the setting of a clinical trial.

Perspective:

Of note is that propensity matching was performed in this analysis to control for confounding variables such as age and comorbidities. Therefore, the results of the study do not apply to patients who are significantly different than the subjects of the clinical trials.

Keywords: Defibrillators, Myocardial Infarction, Follow-Up Studies, Comorbidity, Primary Prevention, Tachycardia, Registries, Confounding Factors, Epidemiologic, Death, Observation, Cardiomyopathies, Heart Failure, Stroke Volume


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