Exercise-recovery hysteresis in the ventricular gradient predicts antiarrhythmic therapy in primary prevention ICD patients

Ejection fraction and microvolt T-wave alternans (mTWA) lack specificity to predict sudden cardiac death in heart failure (HF). We analyzed exercise tests of 34 HF pts with an implanted cardioverter-defibrillator - cases and matched controls with/without antiarrhythmic therapy for VT/VF during follow up -, computing the individual relative exercise-recovery hysteresis, ΔSVG%, in the spatial ventricular gradient (SVG, a measure for action potential morphology heterogeneity) in the 95-110 bpm heart rate range. ΔSVG% differed significantly between cases (-18.1±25.6%) and controls (1.2±28.1%, P=0.003). ROC analysis (AUC=0.737, P=0.02) revealed that ΔSVG% <; 14.8% discriminated cases and controls with 94.1% sensitivity and 41.2% specificity; hazard ratio was 3.03 (1.03-8.96). These results can compete with the performance of mTWA analysis. We conclude that ΔSVG% is a promising additional predictor for lethal arrhythmias in HF pts.