The effect of intracoronary thrombolysis with streptokinase on myocardial thallium distribution and left ventricular function assessed by blood-pool scintigraphy

In order to evaluate the effect of coronary recanalization in acute myocardial infarction, thallium scintigrams were made on admission in 23 patients in whom thrombolysis was attempted and in 27 patients treated conventionally. The scintigrams were repeated immediately after the procedure or after 3 h in the control group. No significant differences were apparent between the initial thallium uptake in treated patients or controls. Some degree of thallium redistribution occurred in 43 out of 50 patients. The degree of redistribution was greater in patients with open or recanalized arteries (redistribution 35%, s.d. 24% of initial defect) than in patients in whom the artery remained occluded (17%, s.d. 12%). No differences were apparent in six patients between the late scintigrams and a third series of images made after an additional injection of thallium. Global left ventricular function was analysed in 30 patients with anteroseptal infarction and in 35 patients with inferior wall infarction. Ejection fractions were lower in patients with anterior wall infarction. Between one and seven days after admission, ejection fractions were similar in patients with open or occluded arteries in pilot studies and in randomized patients with inferior wall infarction after thrombolysis or conventional treatment. In patients with anterior wall infarction, left ventricular ejection fraction after streptokinase (45%, s.d. 7%) was greater than after conventional treatment (38%, s.d. 12%). Analysis of segmental left ventricular function suggests that this difference is due in part to the improvement of segmental function in the non-infarcted areas. No differences were observed between ejection fractions measured early (1–7 days) or late (10–20 days) after myocardial infarction. The data show considerable overlap between patients treated with streptokinase and those treated conventionally. Further randomized trials are needed to determine whether thrombolysis in acute myocardial infarction does indeed result in permanent improvement of myocardial function.