QT dispersion in patients with different etiologies of left ventricular hypertrophy: the significance of QT dispersion in endurance athletes

Left ventricular hypertrophy (LVH) increases the risk of ventricular arrhythmias and sudden death and has a significant effect on total cardiovascular mortality. QT dispersion (QTd) is a measure of inhomogeneous repolarization and is used as an indicator of arrhythmogenicity. In this study we detected QTd in patients with different etiologies of left ventricular hypertrophy and the effect of LVH in QTd on endurance athletes. The study group consisted of 147 white male subjects with 3 different etiologies of LVH and 30 healthy male individuals. The underlying etiologies of LVH were essential hypertension, valvular aortic stenosis and long-term training (athletic heart). QTd was measured by surface electrocardiogram and Bazett's formula was used to correct QTd for heart rate (QTcd). Left ventricular mass was determined by transthoracic echocardiography and left ventricular mass index was calculated in relation to body surface area. The QTcd was significantly higher in patients with pathological LVH (due to hypertension and aortic stenosis) than in the athletes' group (physiological LVH) and healthy subjects (P<0.05). The magnitude of QTcd was similar between athletes and the control group (P=0.6). The difference of QTcd between the groups with pathological LVH was not statistically significant (P=0.1). In conclusion; the increasing of QT dispersion is associated with only pathological conditions of LVH. The left ventricular hypertrophy has not a negative effect in QT dispersion on endurance athletes. The measurement of QT dispersion may be a non-invasive useful method for screening additional pathological conditions in endurance athletes.