Thrombolytic Therapy for Acute Coronary Obstruction: Status in 1986

The effect of thrombolysis in acute myocardial infarction on enzymatic infarct size, left ventricular function, and early mortality was studied in subsets of patients in a randomized trial at The Netherlands Interuniversity Cardiological Institute during a 5-year period. Early thrombolytic therapy with intracoronary streptokinase (152 patients) or with intracoronary streptokinase preceded by intravenous streptokinase (117 patients) was compared to conventional treatment (264 patients). All 533 patients were admitted to the coronary care unit within 4 hours after onset of symptoms indicative of acute myocardial infarction. There were 488 patients eligible for this detailed analysis, of whom 245 were allocated for thrombolytic therapy. Early angiography was performed in 212 of the 245 patients. Patency of the infarct-related artery was achieved in 181 patients (85%). Enzymatic infarct size measured from cumulative alpha HBDH release was smaller in patients allocated to thrombolytic therapy (median 760 U/l vs. 1179 U/l in controls, p = 0.0001). LVEF measured by radionuclide angiography before discharge was higher after thrombolytic therapy (median 50% vs. 43% in controls, p = 0.0001). The 12-month mortality was lower in patients allocated to thrombolytic therapy (8% vs. 16% in the control group, p < 0.01). In multivariate regression analysis, infarct size limitation, improvement of LVEF, and a 3-month mortality were predicted by ST, time from onset of symptoms to admission, and Killip class at admission. Thrombolysis was most useful in patients admitted within 2 hours after onset of symptoms and in patients with ST of 1.2 mV or more. On the other hand, no beneficial effects of streptokinase on enzymatic infarct size, left ventricular function, or mortality were observed in the subset of patients with ST less than 1.2 mV admitted 2 to 4 hours after onset of symptoms.