The terminal portion of the T wave: a new electrocardiographic marker of risk of ventricular arrhythmias.

Experimental studies have shown that transmural dispersion of repolarization (DoR), defined as the difference in action potential duration between mid-myocardial M-cells, epicardial, and endocardial cells is reflected in the duration of the terminal portion of the T wave (TpTe) on the surface ECG. Since DoR is an important factor associated with the propensity for reentrant arrhythmias, this study examined if TpTe may serve as a marker of risk of ventricular arrhythmias. Data from 18 patients with coronary artery disease and inducible sustained ventricular tachycardia (VT group) were compared with those of 16 survivors of myocardial infarction without inducible VT (control group). TpTe was automatically measured in each beat of 24-hour ECG recordings, and programmed ventricular stimulation was performed in the antiarrhythmic drug-free state. TpTe was expressed as the absolute interval in milliseconds, and relative to the duration of QTe (TpTe/QTe x 100%). TpTe duration was 74 +/- 14 ms in the VT group versus 63 +/- 16 ms in the control group (P < 0.004). The TpTe interval expressed as a percent of the QT interval was 21 +/- 4% in the VT group versus 17 +/- 3% in the control group (P = 0.02). In patients with coronary artery disease. TpTe was longer in patients with, versus without, inducible VT. The results of this study support the hypothesis that TpTe reflects transmural dispersion of repolarization.