Incremental benefit of cardiac resynchronisation therapy with versus without a defibrillator

OBJECTIVE: To determine the incremental value of implantable cardioverter defibrillators (ICD) in contemporary optimally treated patients with heart failure (HF) undergoing cardiac resynchronisation therapy (CRT). METHODS: Consecutive patients with HF undergoing CRT-pacemaker (CRT-P) or CRT-defibrillator (CRT-D) implantation in a single tertiary care centre between October 2008 and August 2015 were retrospectively evaluated. For patients with a primary prevention indication of the CRT-D, no benefit of the ICD was defined as absence of appropriate therapy (device analysis) or lethal ventricular tachyarrhythmias (mode of death analysis) during follow-up. RESULTS: 687 patients (CRT-P/CRT-D; n=361/326) were followed for 38±22 months. CRT-P recipients were older (75.7±9.1 vs 71.8±9.3 years; p<0.001) and had a higher comorbidity burden. Five patients with CRT-P (1%) experienced episodes of sustained ventricular-tachycardia vs 64 (20%) patients with CRT-D (p<0.001). Remote tele-monitoring detected the episodes of sustained ventricular tachycardia in four patients with CRT-P, allowing for elective upgrade to CRT-D. All-cause mortality was higher in patients with CRT-P versus CRT-D (21% vs 12%, p=0.003), even after adjusting for baseline characteristics (HR 2.5; 95% CI 1.36 to 4.60; p=0.003). However, mode of death analysis revealed a predominant non-cardiac mode of death in CRT-P recipients (n=47 (71%) vs n=13 (38%) in CRT-D, p=0.002). Multivariate analysis revealed that age >80 years, New York Heart Association class IV, intolerance to beta-blockers and underlying non-ischaemic cardiomyopathy were independently associated with little incremental value of a primary prevention ICD on top of CRT. CONCLUSIONS: The majority of patients with contemporary HF as currently selected for CRT-P exhibit mainly non-cardiac-driven mortality. Weighing risk of ventricular-tachyarrhythmic death versus risk of all-cause mortality helps to address the incremental value of an ICD to CRT-P.