Patterns of QT dispersion in athletic and hypertensive left ventricular hypertrophy.

Objective: The objective of this article is to assess whether left ventricular hypertrophy (LVH) due to physical training or of hypertensive patients shows similarities in QT length and QT dispersion.

Methods: A total of 51 subjects were studied: 17 essential hypertensive patients (27.7 +/- 5.6 years), 17 athletes involved in agonistic activity (canoeing) (24.8 +/- 6.1 years), and 17 normotensive healthy subjects as control group (24.8 +/- 3.6 years). The testing protocol consisted of (1) clinic BP measurement, (2) echocardiography, (3) 12-lead electrocardiographic examination (QT max, QTc max, QT min, QTc min, DeltaQT, DeltaQTc).

Results: There were no significant differences between the body surface area, height, and age of the three groups. Clinic blood pressure was higher in hypertensives (146.5 +/- 45.2/93.5 +/- 4.9 mmHg) versus athletes (120.9 +/- 10.8/77.1 +/- 6.0 mmHg) and controls (123.5 +/- 4.8/78.8 +/- 2.9 mmHg) by definition. Indexed left ventricular mass (LVM/BSA) was significantly greater in both athletes (148.9 +/- 21.1 g/m2) and hypertensives (117.1 +/- 15.2 g/m2) versus controls (81.1 +/- 14.5 g/m2; P < 0.01), there being no statistical difference among them. LVH (LVMI > 125 g/m2) was observed in all athletes, while the prevalence in hypertensives was 50%. In spite of this large difference in cardiac structure there were no significant differences in QT parameters between athletes and the control group, while hypertensive patients showed a significant increase in QT dispersion versus the two other groups (DeltaQT 82 +/- 2.1, 48 +/- 1.3, 49 +/- 2.3 ms; P < 0.01; DeltaQTc 88 +/- 2.0, 47 +/- 1.4, 54 +/- 2.7; P < 0.01).

Conclusions: LVH induced by physical training activity is not associated with an increase in QT dispersion, whereas pathological increase in LVM secondary to hypertension is accompanied by an increased QT dispersion.