Long-term clinical outcomes of cardiac resynchronization therapy with or without defibrillation: impact of the aetiology of cardiomyopathy

Abstract

Aims: There is a continuing debate as to whether cardiac resynchronization therapy-defibrillation (CRT-D) is superior to CRT-pacing (CRT-P), particularly in patients with non-ischaemic cardiomyopathy (NICM). We sought to quantify the clinical outcomes after primary prevention of CRT-D and CRT-P and identify whether these differed according to the aetiology of cardiomyopathy.

Methods and results: Analyses were undertaken in the total study population of patients treated with CRT-D (n = 551) or CRT-P (n = 999) and in propensity-matched samples. Device choice was governed by the clinical guidelines in the United Kingdom. In univariable analyses of the total study population, for a maximum follow-up of 16 years (median 4.7 years, interquartile range 2.4-7.1), CRT-D was associated with a lower total mortality [hazard ratio (HR) 0.72] and the composite endpoints of total mortality or heart failure (HF) hospitalization (HR 0.72) and total mortality or hospitalization for major adverse cardiac events (MACE; HR 0.71) (all P < 0.001). After propensity matching (n = 796), CRT-D was associated with a lower total mortality (HR 0.72) and the composite endpoints (all P < 0.01). When further stratified according to aetiology, CRT-D was associated with a lower total mortality (HR 0.62), total mortality or HF hospitalization (HR 0.63), and total mortality or hospitalization for MACE (HR 0.59) (all P < 0.001) in patients with ischaemic cardiomyopathy (ICM). There were no differences in outcomes between CRT-D and CRT-P in patients with NICM.

Conclusion: In this study of real-world clinical practice, CRT-D was superior to CRT-P with respect to total mortality and composite endpoints, independent of known confounders. The benefit of CRT-D was evident in ICM but not in NICM.

Figure 1

Primary and secondary endpoints according to the device type. The Kaplan–Meier survival curves for clinical outcomes according to the device type in the total patient population. CRT-D, cardiac resynchronization therapy-defibrillation; CRT-P, cardiac resynchronization therapy-pacing; HF, heart failure; MACE, major adverse cardiovascular events.

Figure 2

Ancillary endpoints according to the device type. The Kaplan–Meier survival curves for clinical outcomes according to the device type in the total patient population. CRT-D, cardiac resynchronization therapy-defibrillation; CRT-P, cardiac resynchronization therapy-pacing; HF, heart failure; MACE, major adverse cardiovascular events; SCD, sudden cardiac death; VF, ventricular fibrillation; VT, ventricular tachycardia.

Figure 3

Primary and secondary endpoints according to the aetiology of cardiomyopathy in propensity-matched samples. The Kaplan–Meier survival curves for primary endpoints according to the device type and aetiology of cardiomyopathy. CRT-D, cardiac resynchronization therapy-defibrillation; CRT-P, cardiac resynchronization therapy-pacing; HF, heart failure; ICM, ischaemic cardiomyopathy; MACE, major adverse cardiovascular events; NICM, non-ischaemic cardiomyopathy.

Figure 4

Survival curves according to the device type and the aetiology of cardiomyopathy. The Kaplan–Meier survival curves for clinical outcomes according to the device type and aetiology. CRT-D, cardiac resynchronization therapy-defibrillation; CRT-P, cardiac resynchronization therapy-pacing; HF, heart failure; ICM, ischaemic cardiomyopathy; MACE, major adverse cardiovascular events; NICM, non-ischaemic cardiomyopathy.