The effect of cardiac resynchronization without a defibrillator on morbidity and mortality: an individual patient data meta‐analysis of COMPANION and CARE‐HF

Aims Cardiac resynchronization therapy (CRT) reduces morbidity and mortality for patients with heart failure, reduced left ventricular ejection fraction, QRS duration >130 ms and in sinus rhythm. The aim of this study was to identify patient characteristics that predict the effect, specifically, of CRT pacemakers (CRT‐P) on all‐cause mortality or the composite of hospitalization for heart failure or all‐cause mortality. Methods and results We conducted an individual patient data meta‐analysis of the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) and Cardiac Resynchronization‐Heart Failure (CARE‐HF) trials. Only patients assigned to CRT‐P or control (n = 1738) were included in order to avoid confounding from concomitant defibrillator therapy. The influence of baseline characteristics on treatment effects was investigated. Median age was 67 (59–73) years, most patients were men (70%), 68% had a QRS duration of 150–199 ms and 80% had left bundle branch block. Patients assigned to CRT‐P had lower rates for all‐cause mortality (hazard ratio [HR] 0.68, 95% confidence interval [CI] 0.56–0.81; p