The effect of exercise on the ECG criteria for early repolarization pattern.

ABSTRACT

OBJECTIVE: To determine the effect of exercise and heart rate on the early repolarization (ER) pattern; focusing on the new criteria for identification of ER. METHODS: The ECG measurements on the terminal QRS notch or slur found in early repolarization were quantitated before, during and after exercise; specifically (i) the amplitude at the onset of the notch (Jo) (ii) the amplitude at the peak of the notch (Jp), (iii) the amplitude at the end of the notch (Jt), (iv) the duration from Jo to Jp (D1) and (v) the duration from Jo to Jt (D2). RESULTS: All individuals (N = 21) fulfilling the criteria for ER showed complete disappearance of ER after 3 min of exercise. After 5 min of recovery, 29% of subjects showed return of the ER. The return of ER was dynamic with QRS notching of varying extent, without ST elevation, being evident first. The relationship between heart rate and ER was significant and nonlinear, best fit by a second-order polynomial, suggesting that changes in heart rate with exercise was a factor influencing the presence of the ER pattern and the parameters that define ER. CONCLUSION: Each of the newly defined characteristics of the ER are modified and eventually disappear with exercise. The return of ER was dynamic with QRS notching of varying extent being evident first. The changes correlated with variations in heart rate, during both exercise and recovery, suggesting, in part, a role in the underlying mechanism of ER.