Left ventricular activation-recovery interval variability predicts spontaneous ventricular tachyarrhythmia in heart failure patients

BACKGROUND: Enhanced beat-to-beat variability of repolarization (BVR) is strongly linked to arrhythmogenesis and is largely due to variation in ventricular action potential duration (APD). Previous studies in humans have relied on QT interval measurements; however, a direct relationship between beat-to-beat variability of APD and arrhythmogenesis in humans has yet to be demonstrated. OBJECTIVES: This study aimed to explore the beat-to-beat repolarization dynamics within a heart failure population at the level of ventricular APD. METHODS: 43 patients with heart failure and implanted cardiac resynchronization therapy defibrillator devices were studied. Activation-recovery intervals (ARI) as a surrogate for APD were recorded from the left ventricular epicardial lead while pacing from the right ventricular lead to maintain constant cycle length. RESULTS: During mean follow-up of 23.6±13.6 months, 11 patients sustained VT/VF and received appropriate implantable cardioverter-defibrillator therapies (Anti-Tachycardia Pacing or shock therapy). ARI variability (ARIV) was significantly greater in patients with subsequent VT/VF vs. those without VT/VF (3.55±1.3 ms vs. 2.77±1.09 ms, p=0.047). Receiver operating characteristic curve analysis (AUC 0.71, p=0.046) suggested high and low risk ARIV groups for VT/VF. The Kaplan-Meier survival analysis demonstrated that the time until first appropriate therapy for VT/VF was significantly shorter in the high-risk ARIV group (p=0.028). ARIV was a predictor for VT/VF in the multivariate Cox model (HR, 1.623; 95% CI, 1.1 to 2.393; p=0.015). CONCLUSIONS: Increased left ventricular ARIV is associated with an increased risk of VT/VF in patients with heart failure