Survival of patients receiving a primary prevention implantable cardioverter-defibrillator in clinical practice vs clinical trials

Abstract

Importance: Randomized clinical trials have shown that implantable cardioverter-defibrillator (ICD) therapy saves lives. Whether the survival of patients who received an ICD in primary prevention clinical trials differs from that of trial-eligible patients receiving a primary prevention ICD in clinical practice is unknown.

Objective: To determine whether trial-eligible patients who received a primary prevention ICD as documented in a large national registry have a survival rate that differs from the survival rate of similar patients who received an ICD in the 2 largest primary prevention clinical trials, MADIT-II (n = 742) and SCD-HeFT (n = 829).

Design, setting, and patients: Retrospective analysis of data for patients enrolled in the National Cardiovascular Data Registry ICD Registry between January 1, 2006, and December 31, 2007, meeting the MADIT-II criteria (2464 propensity score-matched patients) or the SCD-HeFT criteria (3352 propensity score-matched patients). Mortality data for the registry patients were collected through December 31, 2009.

Main outcome measures: Cox proportional hazards models were used to compare mortality from any cause.

Results: The median follow-up time in MADIT-II, SCD-HeFT, and the ICD Registry was 19.5, 46.1, and 35.2 months, respectively. Compared with patients enrolled in the clinical trials, patients in the ICD Registry were significantly older and had a higher burden of comorbidities. In the matched cohorts, there was no significant difference in survival between MADIT-II-like patients in the registry and MADIT-II patients randomized to receive an ICD (2-year mortality rates: 13.9% and 15.6%, respectively; adjusted ICD Registry vs trial hazard ratio, 1.06; 95% CI, 0.85-1.31; P = .62). Likewise, the survival among SCD-HeFT-like patients in the registry was not significantly different from survival among patients randomized to receive ICD therapy in SCD-HeFT (3-year mortality rates: 17.3% and 17.4%, respectively; adjusted registry vs trial hazard ratio, 1.16; 95% CI, 0.97-1.38; P = .11).

Conclusions and relevance: There was no significant difference in survival between clinical trial patients randomized to receive an ICD and a similar group of clinical registry patients who received a primary prevention ICD. Our findings support the continued use of primary prevention ICDs in similar patients seen in clinical practice.

Trial registration: clinicaltrials.gov Identifier: NCT00000609.

Conflict of interest statement

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Bardy reported consulting fees, equity, and intellectual property rights in Cameron Health. Dr Mark reported receiving research grants from Eli Lilly, Medtronic, AstraZeneca, and Gilead Sciences. Dr Anstrom reported receiving research support from AstraZeneca, Eli Lilly, and Medtronic; having served as a consultant for Abbott Vascular, AstraZeneca, Bristol Meyer Squibb, and Ikaria; and having served on data monitoring committees for Pfizer and Vertex. Dr J. Curtis reported owning stock in Medtronic and receiving salary support from the American College of Cardiology Foundation, Center for Medicare & Medicaid Services, and National Institutes of Health (NIH)/National Heart, Lung, and Blood Institute (NHLBI). Dr L. Curtis reported receiving research and salary support from Johnson & Johnson, GlaxoSmithKline, Agency for Healthcare Research and Quality, and NHLBI. Dr Curtis has made available online a detailed listing of financial disclosures (http://www.dcri.duke.edu/research/coi.jsp). Dr Heidenreich reported receiving research support from Medtronic. Dr Lee reported receiving modest consulting fees from Medtronic. Dr Moss reported receiving research grants from Boston Scientific and salary support from Boston Scientific, Medtronic, St Jude, and Biotronic. No other disclosures were reported.

Figures

Figure 1

Unadjusted Kaplan-Meier Curves for Survival Among MADIT-II Patients and MADIT-II–like Patients in the ICD Registry Patients compared were MADIT-II–like patients in the ICD Registry, MADIT-II patients randomized to ICD therapy, and MADIT-II patients randomized to medical therapy (for matched patients only). MADIT-II indicates Multicenter Automatic Defibrillator Implantation Trial-II; ICD, implantable cardioverter-defibrillator.

Figure 2

Unadjusted Kaplan-Meier Curves for Survival Among SCD-HeFT Patients and SCD-HeFT–like Patients in the ICD Registry Patients compared were SCD-HeFT–like patients in the ICD Registry, SCD-HeFT patients randomized to ICD therapy, and SCD-HeFT patients randomized to medical therapy only (for matched patients only). SCD-HeFT indicates Sudden Cardiac Death in Heart Failure Trial; ICD, implantable cardioverter-defibrillator.