INFLUENCE OF INFARCT-RELATED ARTERY PATENCY ON THE INDEXES OF PARASYMPATHETIC ACTIVITY AND PREVALENCE OF LATE POTENTIALS IN SURVIVORS OF ACUTE MYOCARDIAL-INFARCTION

Objectives. The purpose of this study was to determine whether infarct -related coronary artery patency influences myocardial electrical stab ility as measured by the prevalence of late potentials or heart rate v ariability. Background. Several studies have suggested that loss of va gal activity is associated with an increased incidence of arrhythmic d eath after myocardial infarction. Methods. A short-duration, high reso lution electrocardiogram (ECG) was performed before hospital discharge in 175 patients with a first myocardial infarction. Seventy-three pat ients received thrombolytic therapy. All patients underwent coronary a ngiography. Coronary occlusion was defined as minimal or no anterograd e flow. Eighty-eight patients (50.3%) had an occluded infarct-related artery. Sixty-two healthy subjects served as control subjects to deter mine the normal range of heart rate variability. Results. Comparison b etween the control group and patients without patency of the infarct-r elated artery in the time domain and spectral analyses revealed in the latter patients a reduced heart rate variability (p < 0.0001) and a l ower power spectrum density in both the 0.05- to 0.15-Hz band (p < 0.0 001) and the 0.15- to 0.35-Hz band (p < 0.0001). The heart rate variab ility in patients with late potentials was lower than in those with a normal signal-averaged ECG. Those patients with spontaneous or thrombo lysis-induced reperfusion have less occurrence of late potentials and higher parasympathetic activity than do patients with a closed artery. Conclusions. This study suggests that the patency of the infarct-rela ted artery determines both the absence of late potentials and the pres ervation of vagal tone and may explain the reduction in mortality indu ced by thrombolytic therapy in myocardial infarction.