Cardiac resynchronization therapy with or without defibrillator in patients with heart failure

Aims: Randomized data on the efficacy/safety of cardiac resynchronization therapy with vs. without defibrillator (CRT-D,-P) in heart failure with reduced ejection fraction (HFrEF) are scarce. We aimed to evaluate survival associated with use of CRT-D vs. CRT-P in a contemporary cohort with HFrEF. Methods and results: Patients from Swedish HF Registry treated with CRT-D/CRT-P and fulfilling criteria for primary prevention defibrillator use were included. Logistic regression was used to evaluate predictors of CRT-D non-use. All-cause mortality was compared in CRT-D vs. CRT-P by Cox regression in a 1: 1 propensity-score-matched cohort. Of 1988 patients with CRT, 1108 (56%) had CRT-D and 880 (44%) CRT-P. Older age, higher ejection fraction (EF), female sex, and the lack of referral to HF nurse-led outpatient clinic were major determinants of CRT-D non-use. After matching, 645 CRT-D patients were compared with 645 with CRT-P. The CRT-D use was associated with lower 1- A nd 3-year all-cause mortality [hazard ratio (HR):0.76, 95% confidence interval (CI):0.58-0.98; HR: 0.82, 95% CI: 0.68-0.99, respectively]. Results were consistent in all pre-specified subgroups except for CRT-D use being associated with lower 3-year mortality in patients with an EF < 30% but not in those with an EF ≥ 30% (HR: 0.73, 95% CI: 0.59-0.89 and HR: 1.24, 95% CI: 0.83-1.85, respectively; P-interaction = 0.02). Conclusion: In a contemporary HFrEF cohort, CRT-D was associated with lower mortality compared with CRT-P. The CRT-D use was less likely in older patients, females, and in patients not referred to HF nurse-led outpatient clinic. Our findings support the use of CRT-D vs. CRT-P in HFrEF, in particular with severely reduced EF.