Experimental study on myocardial salvage by coronary thrombolysis and mechanical recanalization.

Salvage of the ischemic myocardium by coronary thrombolysis and mechanical recanalization (simulated angioplasty) was studied in a canine experimental model of acute myocardial infarction induced by coronary occlusive thrombus at the left anterior descending coronary artery. Forty-four open-chest dogs divided into three groups were studied. Group I (n = 15, control group) was observed for 6 hours following the onset of infarct. In group II (n = 14, thrombolysis group), thrombolysis was obtained by intravenous administration of urokinase 2 hours after the onset of infarct. In group III (n = 15, mechanical recanalization group), simulated angioplasty was performed 2 hours after infarct. Coronary reperfusion was continued for 4 hours in groups II and III. The areas of left ventricular risk and infarct were measured by double staining methods with Evans blue dye and triphenyl tetrazolium hydrochloride. There were no significant differences in control blood flow and risk area in the three groups. Myocardial infarct area/risk area was 65 +/- 3% in group I, 45 +/- 1% in group II, and 35 +/- 2% in group III (group I vs II, p less than 0.001; group II vs III, p less than 0.001). Restored coronary blood flow in the left anterior descending artery was 8 +/- 1 ml/min in group II and 14 +/- 1 ml/min in group III (p less than 0.001). The data suggest that coronary mechanical recanalization is more effective than thrombolysis in salvaging the ischemic myocardium in the early phase of myocardial infarction, most probably because coronary blood flow is better restored by mechanical recanalization.