Background: Thrombolytic therapy has frequently been withheld from patients with complete heart block following acute myocardial infarction because of significant hypotension and the risk of bleeding should temporary transvenous pacing be required. We assessed the course of patients with acute myocardial infarction complicated initially by complete heart block who received thrombolytic therapy.Methods: Patients had clinical and ECG evidence of acute myocardial infarction of less than 6 hours' duration , were in complete heart block when first assessed, and were suitable for thrombolytic therapy. Coronary angiography was performed during the hospital stay, and left ventricular function was assessed by radionuclide ventriculography during convalescence.Results: Twenty-one patients were treated: 20 had an inferior myocardial infarction and 17 patients were first seen outside the hospital. Initial systolic blood pressure in 13 of 21 (62%) was 90 mm Hg or less. Thrombolytic therapy commenced at 154 minutes (mean) after the onset of infarction and 12 patients received prehospital thrombolysis. All patients had received intravenous atropine, and in seven 1:1 atrioventricular conduction had occurred. Of the 12 who remained in complete heart block at the time of receiving the thrombolytic agent, 10 reverted to 1:1 atrioventricular conduction and one to chronic atrial fibrillation within 2 hours. Of the two in second-degree atrioventricular block, both reverted to 1:1 atrioventricular conduction within 7 hours. Only four patients required temporary transvenous pacing (in three for complete heart block). Coronary artery patency was 79% (15 of 19), and mean global left ventricular ejection fraction was 57% +/- 10%. No hemorrhagic complications occurred; only one patient with anterior myocardial infarction and cardiogenic shock died.Conclusions: Thrombolytic therapy administered to patients with myocardial infarction complicated by complete heart block is safe and frequently results in resumption of normal atrioventricular conduction, thus reducing the need for pacing and improving prognosis.

Fifty-nine consecutive patients presenting within 6 hours of the onset of symptoms of an acute myocardial infarction were treated with 150 mg of soluble aspirin orally, and either 70 or 100 mg of alteplase divided into 2 intravenous bolus injections separated by 30 minutes. Dosage regimens were either 20 followed by 50 mg (group A), 50 followed by 20 mg (group B), or 50 followed by 50 mg (group C). Coronary angiography 60 minutes after the first bolus showed infarct-related coronary artery patency (Thrombolysis in Myocardial Infarction score 2 or 3) in 13 of 16 (81%) patients in group A, 12 of 17 (71%) in group B, and 10 of 11 (91%) in group C (overall patency rate at 60 minutes: 35 of 44 [80%] patients; 95% confidence interval 68 to 91%). At 90 minutes, patency rates were 15 of 20 (75%) patients in both groups A and B, and 18 of 19 (95%) in group C (overall patency rate 48 of 59 [81%] patients; 95% confidence interval 72 to 91%). Residual thrombus was identified with the 90-minute angiogram in 7 patients in group A, 5 in group B, and 3 in group C. Although there was no statistically significant difference in patency between the 3 dosage regimens at either 60 or 90 minutes there was a trend toward increased patency and more complete thrombolysis at 90 minutes in group C. No episodes of bradyarrhythmia, hypotension or cerebrovascular bleeding were observed after double bolus therapy. There were 7 episodes (12%) of reocclusion, and 3 deaths (5%) within 1-month follow-up. Double bolus alteplase therapy is a convenient and highly effective method of promoting early coronary artery patency.