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QT dispersion in exercise-induced myocardial hypertrophy
M Halle1, M Huonker, S H Hohnloser
1Department of Internal Medicine, Albert Ludwigs University, Freiburg, Germany.
American Heart Journal
|July 30, 1999
Summary
Endurance training increases left ventricular mass but reduces QT dispersion, indicating homogeneous repolarization. This may explain lower mortality in athletes and help differentiate exercise-induced from disease-related heart changes.
Area of Science:
- Cardiology
- Exercise Physiology
- Electrophysiology
Background:
- QT dispersion measures myocardial repolarization inhomogeneity.
- Elevated QT dispersion is linked to heart disease and arrhythmias.
- Systemic hypertension-induced hypertrophy increases QT dispersion.
Purpose of the Study:
- To investigate the relationship between left ventricular enlargement in endurance-trained individuals and QT dispersion.
- To determine if exercise-induced cardiac hypertrophy affects myocardial repolarization homogeneity.
Main Methods:
- Assessed left ventricular (LV) mass using 2D echocardiography.
- Measured QT dispersion via 12-lead resting electrocardiogram.
- Compared 26 endurance-trained subjects with 26 less-trained controls.
Main Results:
- Endurance-trained subjects exhibited greater LV mass (216 g vs 155 g).
- Endurance-trained subjects had significantly lower heart rate-corrected QTc dispersion (42 ms vs 51 ms).
- LV mass was inversely correlated with QT dispersion (r = -0.38) and QTc dispersion (r = -0.53) across all subjects.
Conclusions:
- Exercise-induced myocardial hypertrophy is not associated with increased QT dispersion.
- Reduced QT dispersion suggests homogeneous repolarization in endurance athletes.
- QT dispersion measurement may help distinguish physiologic from pathologic cardiac hypertrophy.