BACKGROUND:

Patients undergoing cardiac resynchronization therapy (CRT) are at high risk for ventricular arrhythmias (VAs), and risk stratification in this population remains poor.

METHODS AND RESULTS:

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.)

CONCLUSIONS:

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.