Blood rheology in acute myocardial infarction: effects of high-dose i.v. streptokinase compared to placebo.

To compare the haemorheological effects of an i.v. infusion of 1.5 MU of streptokinase with placebo, we investigated the time course of plasma fibrinogen concentration and the haemorheologic parameters plasma viscosity, erythrocyte aggregation and whole blood viscosity at different shear rates during the early phase of acute myocardial infarction until week 3 in 38 unselected patients from the ISAM and ISIS-2 study. Within 3 h, streptokinase led to a near afibrinogenaemia lasting for more than 24 h. Concomitantly, with streptokinase we found a reduction of plasma viscosity, erythrocyte aggregation and whole blood viscosity, whereas with placebo, values showed a slight increase, resulting in significant differences between the groups within the first 2 days. Thereafter, both groups showed an increase in all parameters, values reaching a maximum after 1 week. The streptokinase-induced reduction in blood viscosity may lead to an improvement in microcirculation in the infarction area during the early phase, whereas the hyperviscosity observed independently of therapy after 1 week may lead to an impairment of microcirculation.