Fibrinolytic and plasmin inhibitor activities in patients with acute myocardial infarction.

Fibrinolytic activity and plasmin inhibitor activity were determined by Blue Dextran-fibrin method in patients with acute myocardial infarction. The normal values of fibrinolytic activity and plasmin inhibitor activity were 3.34 +/- 0.74 units and 10.10 +/- 2.39 units (mean +/- SD), respectively. The fibrinolytic activity in normal women (3.63 +/- 0.99 units) was slightly higher than that in normal men (3.17 +/- 0.79 units), but the plasmin inhibitor was not significantly different in the two sexes statistically. Neither activity varied significantly with age. The blood fibrinolytic activity was depressed in the first week after acute myocardial infarction, the decrease being maximal 3 to 4 days after the event (1.73 +/- 0.31 units). The mean plasmin inhibitor activity remained normal after acute myocardial infarction, but it was increased in 3, and decreased in 4 of 7 patients in whom it was measured 3 to 4 days after the event.