Early and late potentials in postinfarction patients.

Injury within the myocardium may cause disturbances of the intraventricular conduction and may be manifested by altered spectrum of the QRS complex. The purpose of this report is to indicate the existence of microvolt early waves appearing at the beginning of the QRS complex in some postinfarction patients with low ejection fraction. The method used incorporated the high resolution ECG recording, where the "pyramid" electrode location was applied. Results indicated a relationship between high frequency potentials, QRS duration time, and ejection fraction, as well as dependence between ventricular tachycardia/fibrillation (VT/VF) occurrence and early and/or late ventricular activity. In patients with secondary VT/VF where early and late potentials were found, the ejection fraction (EF) was the lowest (26 +/- 15%). Early waves appeared more often in patients with secondary VT/VF (30%) compared with those with primary VT/VF (8%). In patients without VT/VF and without myocardial infarction (MI) early potentials were not remarked. In those patients late potentials also appeared less often. It could be concluded that existence of early potentials, late activity, and significant prolonged total ventricular activation time is associated with wide dispersion and nonuniform delay of the electrical activity within the myocardium as well as with serious lowering of the ejection fraction. Therefore, existence of early waves seems to be a significant diagnostic factor for the poor hemodynamic condition as well as a serious warning for the recurrent late ventricular tachycardia/fibrillation.