Incremental benefit of cardiac resynchronisation therapy with versus without a defibrillator

To determine the incremental value of implantable cardioverter defibrillators (ICD) in contemporary optimally treated patients with heart failure (HF) undergoing cardiac resynchronisation therapy (CRT).

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.

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.

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.