QRS fragmentation as a predictor of clinical events in patients undergoing cardiac resynchronization therapy

BackgroundQRS fragmentation (QRSf) has been associated with a worse prognosis in several cardiac diseases, although limited evidence exists on QRSf in patients undergoing cardiac resynchronization therapy (CRT). ObjectivesThis study aimed to determine whether QRSf is associated with clinical events in patients receiving CRT. MethodsQRSf included various patterns present on at least 2 contiguous leads in 3 different territories: anteroseptal (V1-V4), lateral (V5-V6, I, aVL), and inferior (II, III, aVF). Mortality, heart failure (HF) admissions, and arrhythmic events (AEs) were studied. ResultsWe included 244 patients (mean age, 72 {+/-} 10 years; 80% male). CRT with a defibrillator (CRT-D) was implanted in 176 patients. Before implantation, mean QRS width was 158 {+/-} 29 ms, mean LVEF was 25 {+/-} 9%, and 61% had QRSf. With pacing, new QRSf developed in 11.9% of patients and QRSf resolved in 11.5%. After a median follow-up of 36 months, 36.9% of patients died, 37.3% were hospitalized for HF, and 16.5% of those with CRT-D had an AE. On multivariate analysis, pre-implantation QRSf was an independent predictor of all-cause mortality (hazard ratio (HR), 2.79; 95% CI [1.54-5.05]), hospitalization for HF (HR, 3.57; 95% CI [1.94-6.58]), and AEs (HR, 6.99; 95% CI [1.54-31.68]). Patients with persistent or newly developed QRSf after implantation had a worse prognosis than those without QRSf. ConclusionsQRSf before or after CRT has significant prognostic value for all-cause mortality, HF hospitalization, and AEs, and presence of QRSf after implantation also has prognostic significance. Patients with QRSf before or after CRT should be observed more closely, as they have a worse prognosis.