Electrocardiographic T-wave changes are more pronounced in type A than in type B men during mental work.

Phasic changes in heart rate (HR) and electrocardiographic T-wave amplitude (TWA) were monitored in healthy Type A (coronary-prone) and Type B (non-coronary-prone) men during the performance of a difficult arithmetic task. Type As showed significantly greater reductions in TWA as compared to Type Bs, though no group differences were present in HR change. This pattern of results, wherein a significant Type A-B difference was observed in a phasic measure of ventricular performance (TWA), but not in one of supraventricular performance (HR), suggests that Type As experience excessive neurally mediated sympathetic stimulation of the myocardium during mental work.