Comparative effectiveness of cardiac resynchronization therapy with an implantable cardioverter-defibrillator versus defibrillator therapy alone: a cohort study

Abstract

Background: Trials comparing implantable cardioverter-defibrillator (ICD) therapy with cardiac resynchronization therapy with a defibrillator (CRT-D) are limited to selected patients treated at centers with extensive experience.

Objective: To compare outcomes after CRT-D versus ICD therapy in contemporary practice.

Design: Retrospective cohort study using the National Cardiovascular Data Registry's ICD Registry linked with Medicare claims.

Setting: 780 U.S. hospitals implanting both CRT-D and ICD devices.

Patients: 7090 propensity-matched patients older than 65 years with reduced left ventricular ejection fraction (<0.35) and prolonged QRS duration on electrocardiography (≥120 ms) having CRT-D or ICD implantation between 1 April 2006 and 31 December 2009.

Measurements: Risks for death, readmission, and device-related complications over 3 years.

Results: Compared with ICD therapy, CRT-D was associated with lower risks for mortality (cumulative incidence, 25.7% vs. 29.8%; adjusted hazard ratio [HR], 0.82 [99% CI, 0.73 to 0.93]), all-cause readmission (cumulative incidence, 68.6% vs. 72.8%; adjusted HR, 0.86 [CI, 0.81 to 0.93]), cardiovascular readmission (cumulative incidence, 45.0% vs. 52.4%; adjusted HR, 0.80 [CI, 0.73 to 0.88]), and heart failure readmission (cumulative incidence, 24.3% vs. 29.4%; adjusted HR, 0.78 [CI, 0.69 to 0.88]). It was also associated with greater risks for device-related infection (cumulative incidence, 1.9% vs. 1.0%; adjusted HR, 1.90 [CI, 1.07 to 3.37]). The lower risks for heart failure readmission associated with CRT-D compared with ICD therapy were most pronounced among patients with left bundle branch block or a QRS duration at least 150 ms and in women.

Limitations: Patients were not randomly assigned to treatment groups, and few patients could be propensity-matched. The findings may not extend to younger patients or those outside of fee-for-service Medicare.

Conclusion: In older patients with reduced left ventricular ejection fraction and prolonged QRS duration, CRT-D was associated with lower risks for death and readmission than ICD therapy alone.

Primary funding source: Agency for Healthcare Research and Quality.