Significance of primary T wave aberrations in the electrocardiogram of asymptomatic young men, III. Systolic time intervals and autonomic tone.

Fifteen healthy male subjects, aged 18-19 years, with primary T wave aberrations consisting mainly of notches in the T wave without concomitant ST depression (group T) were compared to twenty-six controls of the same age with normal electrocardiograms. The T wave aberrations were eliminated by beta-adrenergic blockade in thirteen subjects in group T. Physical exercise decreased all the T wave aberrations. Group T was on average shorter and had signs of higher sympathetic tone, as shown by a higher heart rate and systolic blood pressure, than the controls and the parasympathetic tone was lower, as indicated by a higher heart rate during beta-adrenergic blockade. No significant differences in physical work capacity and heart volumes were found. Measurement of systolic time intervals suggested increased sympathetic influence on the heart and no signs of cardiac impairment. Thus the majority of subjects with aberrant T waves had changes in the autonomic tone and no signs of functional impairment of the heart.