Platelet hyperaggregability in idiopathic recurrent deep vein thrombosis.

Studies of platlet function were performed in 30 patients with idiopathic recurrent venous thrombosis. Evidence of platelet hyperactivity was found in 14 patients who exhibited spontaneous platelet aggregation and in 13 patients who had evidence of circulating platelet aggregates. No other differences in clinical characteristics or coagulation parameters could be elucidated between these two subgroups. In nine patients who had 51Cr-labeled platelet survival studies, there was a good correlation between the platelet hyperactivity and shortened platelet survival. Spontaneous platelet aggregation was inhibited both in vivo and in vitro by aspirin. In addition, the circulating platelet aggregates were normalized by combination treatment with aspirin and dipyridamole. The results indicate that the idiopathic recurrent venous thrombosis patient population could be differentiated by the platelet function tests into subgroup I, in which no platelet abnormality could be detected, and subgroup II, where platelet hyperaggregability was present. These results indicate that the role of platelets should be considered in the pathogenesis of recurrent venous thrombosis and therapy with agents which inhibit platelet aggregation may be beneficial in the patients with platelet hyperaggregability.