Abstract
BACKGROUND: Patients undergoing cardiac resynchronization therapy with a defibrillator (CRT-D) often experience improvements in the left ventricular ejection fraction (LVEF). This study aimed to identify predictors of ventricular tachyarrhythmias (VTA) in patients with CRT-D devices and LVEF improvement beyond guideline recommendations for a defibrillator. METHODS: Patients randomized to the CRT-D arm of the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy trial who improved their LVEF to > 35% at 12 months following CRT-D implant were included in this analysis (N = 651). Predictors of an appropriate implantable cardioverter defibrillator (ICD) Rx VTA were evaluated by Cox proportional hazards regression modeling. RESULTS: We identified three predictors of VTA among patients treated with CRT-D subsequent to LVEF improvement > 35%: Lower range improvement in LVEF 36%-40% versus improvement to > 40% (HR, 1.97; 95% CI, 1.21-3.20; p = 0.006); Baseline non-LBBB ECG morphology (hazard ratio [HR], 1.93; 95% confidence interval [CI], 1.23-3.04; p = 0.004); Occurrence of VTA during the first year post-CRT-D (HR, 4.91; 95% CI, 2.99-8.07; p < 0.001). CONCLUSIONS: We identified a sub-group of patients with risk factors who remain at high risk of VTA despite improvement in LVEF following CRT implant. These patients require close monitoring despite improvement in LVEF beyond guideline recommendations for an ICD.