Tpe/QT Variability Among Standard ECG Leads: How Not to Miss the Increase in the Tpe/QT Value?

The increased Tpe/QT ratio is a novel, promising predictor of cardiac arrhythmias. However, no consensus exists regarding the Tpe/QT measurement. This study aimed to evaluate Tpe/QT variability among standard ECG leads.

Tpe/QT magnitudes were analyzed in 8 standard ECG leads (I, II, V1–V6) in 33 patients with a definite diagnosis of arrhythmogenic right ventricular cardiomyopathy. Tpe/QT values were calculated in several ways: averaging against 1 or more leads over all the patients and searching the maximum value among all measured leads in each patient (the true maximum), followed by averaging over all the patients.

Maximum and minimum Tpe/QT values were distributed among all the tested ECG leads. In each lead, minimum and maximum Tpe/QT values could be observed in different patients. The dispersion of Tpe/QT magnitudes calculated in various ways reached the value of 0.055.

The Tpe/QT magnitude depends on the method of determining the T-wave ending and the number of ECG leads used for its calculation. To detect the increased Tpe/QT ratio, the analysis of all available ECG leads against 1 or a few leads is preferable.