Determinants of worse prognosis in patients with cardiac resynchronization therapy defibrillators. Are ventricular arrhythmias an adjunctive risk factor?

Abstract

Cardiac resynchronization therapy (CRT) is indicated in patients with systolic heart failure (HF), severe left ventricle (LV) dysfunction and interventricular dyssynchrony.In prospective observational research, we aimed to evaluate whether CRT-induced LV reverse remodelling and occurrence of ventricular arrhythmias (VT/VF) independently contribute to prognosis in patients with CRT defibrillators (CRT-D). In 95 Italian cardiological centres, after a screening period of 6 months, patients were categorized according to VT/VF occurrence and CRT response, defined as LV end-systolic volume relative reduction >15% or LV ejection fraction absolute increase >5%. The main endpoint was death or HF hospitalizations. Among 1308 CRT-D patients (80% male, mean age 66 years), at 6 months, follow-up 71% were identified as CRT responders and 12% experienced appropriate VT/VF detections. The main endpoint was significantly and independently associated with previous myocardial infarction, New York Heart Association Class, VT/VF occurrence and with CRT response. CRT nonresponder patients who suffered VT/VF in the screening period had a risk of death or HF hospitalizations [HR = 7.82, 95% confidence interval (CI) = 3.95-15.48] significantly (P < 0.001) higher than CRT responders without VT/VF occurrence. This risk is mitigated without VT/VF occurrence (HR = 3.47, 95% CI = 2.03-5.91, P < 0.001) or in case of CRT response (HR = 3.11, 95% CI = 1.44-6.72, P = 0.004). Our data show that both CRT response and occurrence of VT/VF independently contribute to the risk of death or HF-related hospitalizations in CRT-D patients. Early VT/VF occurrence may be identified as a marker of disease severity than can be mitigated by CRT response both in terms of all-cause mortality and long-term VT/VF onset. URL: https://www.clinicaltrials.gov. Unique identifier: NCT00147290 and NCT00617175.