INFLUENCE OF THROMBOLYSIS ON SIGNAL-AVERAGED ELECTROCARDIOGRAM AND LATE ARRHYTHMIC EVENTS AFTER ACUTE MYOCARDIAL-INFARCTION

The influence of intravenous thrombolysis on both prevalence of ventricular late potentials and incidence of late arrhythmic events was evaluated in 174 consecutive patients surviving a first acute myocardial infarction; 106 patients (61%) received thrombolysis (group A) and 68 (34%) had conventional therapy (group B). In group A, 18 patients (17%) had late potentials compared with 23 (34%) in group B (p < 0.05); mean left ventricular ejection fraction was not different (0.50 +/- 0.09 vs 0.50 +/- 0.10; p = not significant [NS]). Of 63 patients who underwent coronary arteriography because of postinfarction ischemia, 28 (44%) had a closed infarct-related artery; of these, 11 (39%) had late potentials compared with 3 of 35 (9%) with a patent artery (p < 0.01). Mean left ventricular ejection fraction was not significantly different between the 2 groups (0.49 +/- 0.09 vs 0.53 +/- 0.09; p = NS). At a mean follow-up of 14 +/- 8 months, 8 of 161 patients (5%) had a late arrhythmic event; 6 of 8 (75%) with and 28 of 153 (18%) without events had late potentials (p < 0.001). In group A, 4 of 99 patients (4%) had events compared with 4 of 62 (6%) in group B (p = NS, relative risk 1.6). Of 24 patients with anterior wall AMI and left ventricular dyskinesia, 6 events occurred. In this group of patients, a higher rate of events was observed (25%); 3 of 16 (19%) treated with thrombolysis had an event compared with 3 of 8 (37%) treated conventionally (p = NS, relative risk 2.6). Thrombolysis and patency of the infarct-related artery significantly reduce the rate of late potentials independently of global left ventricular function. Although no significant difference was found in the follow-up results, the reduced rate of late potentials suggests an improved ventricular electrical stability both in patients treated with thrombolysis and in those with a patent vessel.