T-wave alternans phase following ventricular extrasystoles predicts arrhythmia-free survival

Objective: The purpose of this study was to assess the value of T-wave alternans (TWA) following ventricular extrasystoles in predicting arrhythmia-free survival. Background: Stratifying risk for sudden death in patients with coronary disease and moderate left ventricular (LV) dysfunction remains a challenge. We hypothesized that, in such patients, a discontinuity in beat-to-beat T-wave alternation (TWA phase reversal) following single ventricular extrasystoles reflects transiently exaggerated repolarization dispersion, and predicts spontaneous ventricular arrhythmias. Methods: We studied 59 patients with ischemic LV dysfunction (mean LV ejection fraction 38.7 ± 5.3%) and nonsustained ventricular tachycardia undergoing programmed stimulation. TWA was computed spectrally from the ECG during ventricular pacing, and TWA phase reversal was reflected by a discontinuity in T-wave oscillation after single ventricular extrasystoles. Results: Patients induced into ventricular arrhythmias (n = 36) had greater TWA magnitude (V_alt: 6.60 ± 6.46 μV vs 2.61 ± 1.97 μV; P = .001) and more frequent TWA phase reversal (62.1% vs 44.4%; P = .02) than those who were not (n = 23). During a mean follow-up of 36 ± 12 months, positive TWA (V_alt ≥1.9 μV) and TWA phase reversal both (P < .05) predicted events (all-cause mortality, ventricular tachycardia, ventricular fibrillation). Univariate predictors of arrhythmia-free survival were TWA phase reversal (P < .005), positive TWA (P < .05), age (P = .008), and LV mass index (P = .043). On multivariate analysis, only TWA phase reversal and age predicted events; if TWA phase was excluded, only positive TWA and age predicted events. Conclusion: Phase reversal in TWA following ventricular extrasystoles predicts spontaneous ventricular arrhythmias and all-cause mortality in patients with moderate ischemic LV dysfunction and was a better predictor than positive TWA 0or programmed ventricular stimulation.