The effects of exercise on late potentials

The effects of exercise on late potential (LP) development were studied on twelve normal patients and nineteen patients with chronic coronary heart disease (CHD). The parameters studied were the QRS duration (QRS), the duration of signals having potential less than 40 μmV (DUR LAS), and root mean square of the potentials in the last 40 ms of the QRS complex (RMS-40). The conclusions were: (1) QRS reduction, RMS-40 increase, and DUR LAS reduction in normal patients could be attributed to the augmented sympathetic drive and the homogeneity of the normal myocardial depolarization; (2) the opposite changes that were observed in CHD patients could be attributed to ventricular conduction delay related to pathological lesions and physiopathologic disturbances due to ischemia; and (3) post-exercise LPs appearing for the first time on CHD patients could be precursors of malignant ventricular arrythmias