Abstract des Autors

The measurement of QT dispersion in the surface ECG is a non-invasive method for assessing inhomogeneity of myocardial repolarization. Elevated QT dispersion is associated with an increased incidence of arrhythmic events and is also increased in hypertensive myocardial hypertrophy. However, the relationship between left ventricular (LV) enlargement in endurance trained subjects and QT dispersion is unknown. In this study LV volume (two-dimensional echocardiography) and QT dispersion were assessed in 75 healthy untrained and endurance trained subjects. Endurance trained subjects had a significantly greater LV volume (715+/-116 ml vs 972+/-171 ml, p<0.001) but lower heart rate corrected QT dispersion (42+/-13 ms vs 50+/-15 ms, p=0.002) than untrained controls. When all individuals were included, LV heart volume was inversely correlated with QT dispersion (r=-0.38; p=0.002). These data show that myocardial hypertrophy induced by exercise training is not associated with increased QT dispersion as in systemic hypertension. The reduced QT dispersion reflects homogeneous myocardial repolarization and may help to explain the reduced mortality in regularly exercising subjects. lf confirmed in further studies, the measurement of QT dispersion could provide a simple and inexpensive screening method for differentiating between physiological and pathological myocardial hypertrophy. This measurement should therefore be introduced and validated in sports medicine. Verf.-Referat