Emergency percutaneous transluminal coronary angioplasty (PTCA) was performed during an acute myocardial infarction (AMI) after either systemic or intracoronary thrombolytic therapy in six patients with severe ischaemic left ventricular dysfunction or cardiogenic shock, among 37 patients (17%) who were treated with PTCA during AMI over a 13-month period. Thrombolytic therapy with streptokinase (1.5 x 10 Units) was initiated after a mean (+/- SD) time delay of 5.5 +/- 1.3 h from the onset of symptoms. The infarct-related artery was found to be occluded (TIMI grade 0-1) in three patients and partially reperfused (TIMI grade 2) in the remaining patients at baseline coronary angiography. Intracoronary administration of urokinase (100-200,000 Units) was ineffective in those patients failing systemic thrombolysis and resulted in only a slight increase of residual lumen in three patients. The coronary artery could be opened by a guidewire mechanical technique in patients with persistent coronary artery occlusion and coronary dilation could be done in all patients. The mean percentage diameter stenosis of the infarct-related vessel was reduced from 98.8 +/- 2% to 27 +/- 11% (P less than 0.005). After the procedure, left ventricular ejection fraction increased from 27 +/- 8% to 41 +/- 7% (P less than 0.02), systemic blood pressure and cardiac index increased respectively from 86 +/- 10 to 126 +/- 14 mmHg (P less than 0.005) and from 2.2 +/- 0.6 to 3.3 +/- 0.6 (P less than 0.01). Left ventricular end-diastolic pressure decreased from 26 +/- 8 to 18 +/- 3 mmHg (P less than 0.05). Severe mitral regurgitation was relieved in one patient.(ABSTRACT TRUNCATED AT 250 WORDS)