Streptokinase and reduced plasma viscosity: A second benefit

The purpose of this pilot study on a small cohort of patients (n = 13) with acute myocardial infarction receiving systemic streptokinase (STK) thrombolytic therapy was to measure the decrease in plasma viscosity concomitant with fibrinogen depletion. The treatment group was compared with a similar control group not given thrombolytic therapy. Serial relevant blood studies were undertaken in both groups for a period of 6 d. In the treatment group, a maximum reduction in plasma viscosity of 17 +/- 9% (mean +/- S.D.) was achieved during the first 24 h. Plasma viscosity remained below baseline for the 6-d duration of the study. Conversely, in the control group, the plasma viscosity rose to a maximum of 19 +/- 14% (mean +/- S.D.) over the period of study, paralleling the rise in plasma fibrinogen as an acute-phase reactant. Correlation studies between viscosity and plasma fibrinogen were strongly positive with mean values of r of 0.74 and 0.66 in the STK-treated group and controls, respectively. We conclude that the benefit of systemic STK treatment may in part be due to reduced myocardial workload and oxygen consumption at a critical time, and improved microvascular circulation, consequent on reduced plasma viscosity.