DOES LATE REVASCULARIZATION ALTER THE EVOLUTION OF THE SIGNAL-AVERAGED ELECTROCARDIOGRAM IN PATIENTS WITH A RECENT TRANSMURAL MYOCARDIAL-INFARCTION

BACKGROUND AND OBJECTIVES: Early infarct-related artery patency associ ated with thrombolytic therapy decreases the incidence of signal-avera ged electrocardiogram (SAECG) derived late potentials following acute a wave myocardial infarction. The purpose of this prospective study wa s to follow the development of SAECG abnormalities in patients with pe rsistent occlusion of the infarct-related artery, and to compare the c ourse of those who subsequently had successful late percutaneous trans luminal coronary angioplasty and coronary artery bypass grafting surge ry with the course of those who were not revascularized. METHODS: Base line (24+/-25 days after myocardial infarction) SAECG studies were acq uired from 39 patients just before revascularization of the infarct-re lated artery (group 1) and from 32 nonrevascularized patients (group 2 ). Late potentials were found in 19 group 1 patients and in 13 group 2 patients (not significant). Follow-up studies were done 103+/-63 days after baseline acquisition. RESULTS: There were no differences betwee n the two groups in the change in filtered QRS (FQRS), in low amplitud e signal duration under 40 mu V (LAS), or in the root mean square volt age of the last 40 ms (RMS). No difference was found in the frequency of resolution of late potentials (21.0% in group 1 versus 38.5% in gro up 2). Patients in whom late potential resolution occurred had less ab normal LAS than patients with persistent late potentials, and less abn ormal RMS. In addition, the magnitude of change in the fQRS, LAS and R MS was significantly greater in patients with late potential resolutio n than in those with late potential persistence. CONCLUSIONS: Late rev ascularization of an occluded infarct-related artery does not appear t o enhance resolution of late potentials compared with conservative med ical therapy. Resolution occurs in patients with less severe SAECG abn ormalities. This may reflect a difference in arrhythmogenic substrate.