Predictors of Sustained Ventricular Arrhythmias in Cardiac Resynchronization Therapy

Abstract

Patients undergoing cardiac resynchronization therapy (CRT) are at high risk for ventricular arrhythmias (VAs), and risk stratification in this population remains poor. This study followed 269 patients (left ventricular ejection fraction <35%; QRS >120 ms; New York Heart Association class III/IV) undergoing CRT with a defibrillator for 553±464 days after CRT with defibrillator implantation to assess for independent predictors of appropriate device therapy for VAs. Baseline medication use, medical comorbidities, and echocardiographic parameters were considered. The 4-year incidence of appropriate device therapy was 36%. A Cox proportional hazard model identified left ventricular end-systolic diameter >61 mm as an independent predictor in the entire population (hazard ratio [HR], 2.66; P=0.001). Those with left ventricular end-systolic diameter >61 mm had a 51% 3-year incidence of VA compared with a 26% incidence among those with a less dilated ventricle (P=0.001). Among patients with left ventricular end-systolic diameter ≤61 mm, multivariate predictors of appropriate therapy were absence of β-blocker therapy (HR, 6.34; P<0.001), left ventricular ejection fraction <20% (HR, 4.22; P<0.001), and history of sustained VA (HR, 2.97; P=0.013). Early (<180 days after implant) shock therapy was found to be a robust predictor of hospitalization for heart failure (HR, 3.41; P<0.004) and mortality (HR, 5.16; P<0.001.) Among patients with CRT and a defibrillator, left ventricular end-systolic diameter >61 mm is a powerful predictor of VAs, and further risk stratification of those with less dilated ventricles can be achieved based on assessment of ejection fraction, history of sustained VA, and absence of β-blocker therapy.