QRS complex fragmentation persistence after cardiac resynchronization therapy with defibrillator in patients with heart failure and reduced ejection fraction as a predictor of arrhythmic events

Introduction Cardiac resynchronization therapy with defibrillator (CRT-D) reduces the risk of sudden death in heart failure with reduced ejection fraction (HFrEF), with a greater benefit in patients with ischemic heart disease (IHD). Fragmented QRS (fQRS) is associated with a worse prognosis in various heart diseases, but its role in CRT-D concerning the aetiology of the underlying disease remains unknown. Objective To assess the prognostic value of fQRS and its variations before and after CRT-D in terms of arrhythmic events (AEs) according to the aetiology of the heart disease. Methods Patients who underwent CRT-D (2009–2022) were included and categorized based on the presence of IHD or non-ischemic cardiomyopathy (nIHD). fQRS before and after CRT-D was defined as different RSR' patterns: additional R waves (R′) and notches in R and S waves in two contiguous leads. Four categories were established based on the presence of fQRS or non-fragmented QRS (nfQRS) before and after implantation. The primary outcome was AE, defined as appropriate defibrillator therapy (anti-tachycardia pacing or appropriate shock) for a ventricular arrhythmia (VA) or as untreated sustained VA. Results A total of 176 patients were included (100 with IHD). Baseline characteristics are shown in Table 1. The median follow-up was 37 months, with 29 documented AEs (15 in IHD patients, 14 in nIHD patients, p=0.545). Multivariate Cox regression, stratified by heart disease type, showed that the presence of fQRS before and after implantation was associated with AEs in IHD patients (HR 4.61; 95% CI 1.02–20.80). The disappearance or development of fQRS after CRT-D, as well as fQRS in nIHD, was not associated with a worse prognosis (Table 2). Conclusions IHD patients who maintain fQRS after CRT-D have a higher risk of AEs, whereas those with pre-implant nfQRS or resolution of fQRS after CRT-D do not present a worse prognosis.Table 1.Baseline characteristics Table 2.Cox regression