The effect of sequential high-dose intravenous streptokinase (SK) (1.5 million units) followed by emergency percutaneous transluminal coronary angioplasty (PTCA) on preserving left ventricular function was assessed prospectively in 34 patients with acute myocardial infarction (AMI). Intravenous SK therapy was initiated 2.6 +/- 1.3 hours (mean +/- standard deviation) after the onset of chest pain. Urgent coronary angiography showed persistent total occlusion in 13 patients, significant diameter stenosis (70 to 99%) in 18 patients and a widely patent artery (less than 50% stenosis) in 3 patients. Emergency PTCA was performed in 29 patients 5.0 +/- 2.1 hours after symptom onset. Successful recanalization was achieved in 33 of the 34 patients (97%) treated with sequential therapy. Repeat contrast ventriculograms recorded 7 to 10 days after intervention in 23 patients showed that the left ventricular ejection fraction increased from 53 +/- 12% to 59 +/- 13% (area-length method, p less than 0.002). Regional wall motion of the infarcted segments improved from -2.7 +/- 1.1 to -1.5 +/- 1.7 SD/chord (centerline method, p less than 0.003). In the subgroup of patients with an occluded artery on initial angiography (group A, n = 10), both global left ventricular ejection fraction (49 +/- 12% vs 59 +/- 12%, p less than 0.002) and regional wall motion (-3.2 +/- 1.0 vs -1.9 +/- 1.7 SD/chord, p less than 0.002) improved significantly. In contrast, no significant improvement was seen in patients with a patent artery on initial angiography (n = 13). Thus, sequential intravenous SK and emergency PTCA is efficacious in achieving coronary reperfusion and in improving both global and regional left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)