Cardiac resynchronization therapy benefit holds up in clinical practice

The benefit of cardiac resynchronization therapy with a defibrillator (CRT-D) relative to implantable cardioverter-defibrillator (ICD) therapy alone has not been evaluated in routine clinical practice.  This study used data from the National Cardiovascular Data Registry’s ICD Registry linked with Medicare claims data to compare outcomes after CRT-D and ICD implantation in community practice.  The analysis included 7090 propensity matched patients who underwent either CRT-D or ICD implantation between 2006 and 2009 at one of 780 U.S. hospitals participating in the NCDR ICD registry.  Patients were over age 65 and met criteria for CRT-D implantation (left ventricular ejection fraction ≤ 35% and QRS duration ≥ 120ms). Over 3 years of follow-up, CRT-D was associated with lower risk of mortality (HR 0.82, 99% CI 0.73-0.93), all-cause readmission (HR 0.86, 99% CI 0.81-0.93), and heart failure readmission (HR 0.78, 99% CI 0.69-0.88) compared with ICD therapy.  However, CRT-D was also associated with a higher risk of device related infection (HR 1.90, 99% CI 1.07–3.37).  In subgroup analyses, the reduced risk of heart failure readmission was most prominent among patients with left bundle branch block or QRS duration of at least 150 ms.


In routine clinical practice, patients who were eligible for CRT-D therapy according to criteria based on the findings of clinical trials experienced better long-term outcomes than patients treated with ICD alone.  These findings suggest the benefits observed in highly controlled clinical trials of CRT-D have translated into patient benefit in for properly selected patients in routine clinical practice

  • Masoudi FA, Mi X, Curtis LH, Peterson PN, Curtis JP, Fonarow GC, Hammill SC, Heidenreich PA, Al-Khatib SM, Piccini JP, Qualls LG, Hernandez AF. Comparative Effectiveness of Cardiac Resynchronization Therapy With an Implantable Cardioverter-Defibrillator Versus Defibrillator Therapy Alone. A Cohort StudyComparative Effectiveness of Cardiac Resynchronization Therapy. Annals of Internal Medicine. 2014;160:603–611.

Summarized by Steven M. Bradley and Preston M. Schneider