Microvolt T-Wave and Ventricular Repolarization Duration Alternans

The ventricular tachyarrhythmia is an important cause of sudden cardiac death, impacting economic, social, and health systems. Microvolt T-wave alternans (MTWA) represent transmural gradient alternation in phase-3 ventricular action potential duration, leading to T-wave amplitude shortening in every other beat. The T-peak T-end interval (TpTe) represents the terminal ventricular repolarization duration and is explained by differences in phase-3 repolarization times from ventricular epicardial to endocardial fibers. Whether TpTe alternation occurs in patients with MTWA is unknown. This work investigated whether terminal ventricular repolarization duration alternation is present in MTWA patients. Seven 12-lead ECG records from Physionet T-wave Alternans Database were analyzed. The TpTe alternans was assessed in even and odds beats, in a series of 128 consecutive beats. In even and odd beats, TpTe intervals were ensembled and averaged, and the magnitude of TpTe alternans was defined as the difference between averages (ΔTpTe). The MTWA was quantified by the difference between the average peak of the T-wave in even and odd beats. ΔTpTe and MTWA were compared by Pearson’s coefficient. Even and odd beats on TpTe alternans and MTWA were compared with non-paired Student t-tests. ΔTpTe positively correlated with MTWA (r = 0.5; p < 0.05). In TpTe anal-ysis, averaged oddly and even beats showed significant differences (p < 0.05). Also, MTWA showed differences in T-wave peaks by comparing average even and odd beats. The present study provides evidence that beat-to-beat TpTe alternation is present among subjects with MTWA and is a potential marker for life-threatening ventricular arrhythmia.