Microvolt T-Wave Alternans in Adolescent Elite Athletes

Microvolt T-wave alternans (MTA) is one of markers of electrical myocardial instability. Study aim: to elucidate normal range of MTA parameters during bicycle exercise test (El) in adolescent elite athletes. Material and methods. We examined 500 athletes aged 9 +/- 18 (mean 16.1 +/- 2.2) years members of national teams of 27 kinds of sport. There were 333 females with mean age 16.0 +/- 1.01 years and 167 males with mean age 16.3 +/- 1.4. All athletes underwent ECG registration in clino- and ortho- positions and bicycle ET with automatic analysis of MTA T-wave alternans. Results. Mean MTA value was 26 +/- 13 (9-51) mV. MTA above 65 mV was registered in 10 persons (2.1%) 5 of whom had signs of overtraining. Sensitivity (Se) of MTA for detection of overtraining state was 21%, specificity (Sp) - 99%, positive and negative predictive value - 50 and 96%, respectively. Conclusion. Normal MTA range during ET is 9-51 mV. MTA values during a do not depend on age and sex but are determined by duration of participation in sports and myocardial mass. MTA value is related to length of QT-interval. Increase of maximal MTA values above 65 mV is insensitive (Se 21%) but highly specific (Sp 99%) sign of overtraining in adolescent elite athletes.