Prognostic value of T-wave alternans in survivors of ventricular fibrillation or hemodynamically unstable ventricular tachycardia

BackgroundT-wave alternans is useful for predicting the occurrence of ventricular tachyarrhythmias and sudden cardiac death in various heart diseases. However, little is known about the clinical significance of T-wave alternans measurement in survivors of ventricular fibrillation (VF) or hemodynamically unstable ventricular tachycardia (VT).MethodsWe studied 28 patients with organic heart disease who survived VF or hemodynamically unstable VT (20 males, mean age 63 years). Echocardiography, electrocardiogram (QRS duration and QTc intervals), and Holter monitoring (heart rate variability, heart rate turbulence and T-wave alternans) were performed before implantable cardioverter-defibrillator (ICD) implantation. Positive T-wave alternans was defined as >65 μV. During the follow-up period (10.2±6.2 months), ventricular tachyarrhythmias requiring appropriate shock therapy occurred in eight patients (29%). The subjects were divided into two groups, based on whether appropriate shock therapy was required (n=8, Group A) or not (n=20, Group B). Parameters from echocardiography, electrocardiogram, and Holter monitoring were compared between the two groups in order to investigate their relationship with the incidence of shock therapy after ICD implantation.ResultsThe prevalence of positive T-wave alternans was significantly higher in Group A than in Group B (88% vs. 15%, P=0.004). Univariate Cox proportional hazard analysis showed that, among the variables measured, only T-wave alternans had predictive power for recurrent ventricular tachyarrhythmias (hazard ratio, 13.17; 95% confidence interval: 1.606–108.1, P=0.016).ConclusionsThese results suggest that T-wave alternans by Holter monitoring is useful for predicting recurrent ventricular tachyarrhythmias in survivors of VF or hemodynamically unstable VT.