[The behavior of late potentials in myocardial infarct patients undergoing myocardial revascularization].

Ventricular late potentials recorded on the body surface in patients with old myocardial infarction (MI) are considered to reflect slow conduction, due to the presence in the infarct border zone of viable myocardium within scarred tissue. To assess the prevalence of late potentials in a population with old MI and no malignant arrhythmias and to verify whether myocardial revascularization may influence the substrate responsible for the occurrence of late potentials, 80 patients with old MI (75 males, 5 females), aged 55 +/- 9 years, undergoing coronary surgery, were studied. A Marquette MAC15 HiRes electrocardiogram recorder was used to identify late potentials before and after surgery. Late potentials were defined following the most accepted criteria reported in the literature. Statistical analysis was performed using logistic regression to determine the association of several clinical, hemodynamic and surgical variables with the presence of late potentials. Late potentials were present in 28 patients (35%) before surgery and disappeared in 11 (39%) after surgery. Inferior MI and female sex were the only independent predictors of the presence of preoperative late potentials. On the other hand, persistence of late potentials after surgery was related to the presence of inferior MI and left ventricle aneurysm. These data suggest that revascularization is capable of abolishing late potentials, probably due to functional recovery of perinecrotic hibernated myocardium. With particular anatomic conditions (inferior MI, aneurysm), this functional recovery seems not to be sufficient for the disappearance of late potentials.