BACKGROUND Treatment of patients with acute myocardial infarction should aim to restore blood flow in the infarct-related artery as soon as possible. Thrombolytic therapy has recently been compared with direct angioplasty; however, these interventions may not be sufficient, and coronary artery bypass grafting (CABG) may be necessary. METHODS In a series of 301 patients with acute myocardial infarction, randomly assigned either to receive intravenous streptokinase (n = 149) or to undergo percutaneous transluminal coronary angioplasty (PTCA; n = 152), 31 patients (aged 61 +/- 10 years; 27 men, four women) underwent CABG within 6 weeks of acute myocardial infarction. RESULTS Twelve patients (nine in the PTCA group and three in the streptokinase group) underwent surgery within 48 h of the onset of symptoms. Bypass surgery was performed in the streptokinase group on failure of thrombolytic therapy (n = 2), recurrent ischemia (n = 4), or postinfarct angina (n = 9). In the PTCA group, CABG was performed for left main stenosis (n = 6), failed PTCA (n = 3), recurrent ischemia (n = 2), or postinfarct angina (n = 5). An intra-aortic balloon pump (IABP) was required in 15 patients (five streptokinase and 10 PTCA). Major complications after CABG were more common among patients who underwent surgery within 48 h than those after 48 h (eight in 12 patients versus four in 19, respectively). After 17.0 +/- 8.6 months (range 3-33 months), two patients had died; one of end-stage heart failure after 3 months, and one of a stroke after 16 months (both were in the PTCA group and one had undergone surgery within 48 h). One patient suffered a reinfarction after 11 months and one a non-fatal stroke after 1 month (both underwent CABG within 48 h). The left ventricular ejection fraction did not differ between the groups (43 +/- 15% for the 'early' group and 42 +/- 11% for the 'late' group). CONCLUSIONS CABG can be performed safely and effectively after initial treatment with direct angioplasty or thrombolytic therapy after acute myocardial infarction. If it is performed within 48 h of onset of symptoms, (in-hospital) morbidity is higher, without affecting mortality or left ventricular function.