ELECTROCARDIOGRAPHIC INDEXES OF DISPERSION OF VENTRICULAR REPOLARIZATION - AN ISOLATED HEART VALIDATION-STUDY

Objectives. This study tested the correlation of QT and JT dispersion and other potentially useful electrocardiographic (ECG) indexes with d ispersion of repolarization and recovery time. Background. Dispersion of ventricular repolarization is currently being assessed noninvasivel y from the surface ECG by means of QT and JT dispersion, although thei r correlation with dispersion of repolarization as measured directly f rom the myocardium is not well established. Methods. Multiple monophas ic action potentials were recorded simultaneously with a 12-lead ECG f rom isolated Langendorff-perfused rabbit hearts. The QT and JT dispers ion was compared with the dispersion of monophasic action potential du ration at 90% repolarization (APD(90)) and with dispersion of recovery time. As new ECG indexes, total T wave area, T wave area after the pe ak Gate T wave area) and T peak to T end interval were also tested. Re sults. The QT and JT dispersion showed a significant correlation with the dispersion of APD(90) and the dispersion of recovery time (r value s between 0.58 and 0.64, respectively, p < 0.001). However, total T wa ve area showed better correlation, respectively, with dispersion of AP D(90) and recovery time (r = 0.79 and r = 0.82, p < 0.0001), as did la te T wave area (r = 0.81 and r = 0.81, p < 0.0001) and T peak to T end interval (r = 0.81 and r = 0.82, p < 0.0001).Conclusions. The JT and QT dispersion correlate significantly with dispersion of APD(90) and r ecovery time. The ECG assessment of dispersion of repolarization can b e improved by three new ECG dispersion indexes: T peak to T end interv al, total T wave area and late T wave area. These new indexes should b e tested clinically.