The signal-averaged electrocardiogram and ventricular arrhythmias after thrombolysis for acute myocardial infarction.

The prevalence of an abnormal signal-averaged electrocardiogram (ECG) and ventricular arrhythmias on 24 h ambulatory electrocardiography was evaluated in 118 patients 13 +/- 2 days after acute myocardial infarction. Group 1 (46 patients) underwent intravenous thrombolysis within 6 h of the onset of symptoms, whereas Group 2 (72 patients) did not. An abnormal signal-averaged ECG was seen in 15% of patients in Group 1 and 21% of those in Group 2 (difference not significant). The number of ventricular premature complexes/h was lower in Group 1 than in Group 2: 2.58 +/- 1.63 versus 7.91 +/- 10.75 (p less than 0.01). However, complex arrhythmias (greater than or equal to 10 ventricular premature complexes/h or ventricular tachycardia) were equally common in Groups 1 and 2 (20% versus 22%, respectively). Their prevalence was similar in patients with or without an abnormal signal-averaged ECG (29% versus 18%, respectively, in Group 1 and 27% versus 21%, respectively, in Group 2). Comparison between patients with (n = 26) or without (n = 20) angiographic patency of the infarct-related coronary artery after thrombolysis showed no significant difference in the prevalence of an abnormal signal-averaged ECG (8% versus 25%, respectively) and complex ventricular arrhythmias (19% versus 20%, respectively). These data suggest that thrombolysis does not affect the prevalence of complex ventricular arrhythmias and an abnormal signal-averaged ECG or their relation after acute myocardial infarction.