Paradoxic elevation of fibrinopeptide A after streptokinase: evidence for continued thrombosis despite intense fibrinolysis.

Elevated levels of fibrinopeptide A, a marker of thrombin activity associated with acute myocardial infarction, have been found to decrease after administration of streptokinase when reperfusion occurs. In contrast, in patients without reperfusion and those with reocclusion after streptokinase therapy, fibrinopeptide A remains elevated. In the present study early serial measurements of fibrinopeptide A were used to further characterize this paradoxic increase in thrombin activity after streptokinase and to characterize its response to heparin. In 19 patients with acute myocardial infarction fibrinopeptide A was elevated to 82.3 +/- 43.5 ng/ml (mean +/- SE) before therapy. Thirty minutes after the initiation of streptokinase, fibrinopeptide A increased to 300.1 +/- 117.4 ng/ml (p less than 0.01), consistent with extensive thrombin activity. Fibrinopeptide A remained elevated until 15 minutes after a heparin bolus injection when levels decreased to 15% of the poststreptokinase value (49.2 +/- 13.3 ng/ml) (p less than 0.001). These data document a prompt paradoxic increase in thrombin activity after administration of streptokinase that may be responsible for failure of therapy in some patients.