[Microvolt T-Wave Alternans in Adolescent Elite Athletes]

Microvolt T-wave alternans (MTA) is one of markers of electrical myocardial instability.To elucidate normal range of MTA parameters during bicycle exercise test (ET) in adolescent elite athletes.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 MTAT-wave alternans.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.Normal MTA range during ET is 9-51 mV. MTA values during ET 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.