Effects of early high-dose streptokinase intravenously on left ventricular function in acute myocardial infarction

Abstract

One hundred seven patients who recently had acute myocardial infarction were randomly assigned either to standard heparin therapy or to intravenous streptokinase within 5 hours after the onset of symptoms in 7 hospitals without catheterization facilities. In the third week, the patients were referred to a university hospital, where the patency rate of the infarctrelated artery was studied by selective coronary arteriography and left ventricular function by radionuclide angiography. Fifty-five patients received heparin and 52 streptokinase within a mean period of 190 minutes after the onset of symptoms. Seven patients in the heparin group and 4 in the streptokinase group died in hospital. The patency rate of the infarct-related artery was identical in both groups (69% in the heparin group vs 68% in the streptokinase group). Left ventricular ejection fraction was not statistically different (0.44 ± 0.13 in the heparin group vs 0.45 ± 0.12 in the streptokinase group). Left ventricular ejection fraction was significantly higher in patients with a patent infarct-related artery than in patients with an obstructed infarct-related artery (0.49 ± 0.12 vs 0.41 ± 0.15, p < 0.01). In patients with inferior wall infarction, left ventricular ejection fraction was identical (0.50 ± 0.10 in the heparin group vs 0.52 ± 0.09, in the streptokinase group). In patients with anterior wall infarction, left ventricular ejection fraction was significantly higher in the streptokinase group than in heparin group (0.40 ± 0.10 vs 0.33 ± 0.09, p < 0.05). Analysis of regional wall motion revealed that improvement occurred in the lateral wall of the left ventricle. After a mean follow-up of 23 months, 3 patients in the heparin group and 1 patient in the streptokinase group died, yielding the mortality rate at the end of the follow-up period to 18.1 % in the heparin group on 9.6% in the streptokinase group. Thus, early intravenous administration of streptokinase may lead to significant preservation of left ventricular function in patients with anterior wall infarction. One may question the suitability and utility of intravenous thrombolysis in inferior wall infarction.