Platelets, thromboembolism and mitral valve prolapse.

Cerebral and retinal ischemic events have been described in mitral valve prolapse. To determine whether platelets play a part in the pathogenesis of thromboembolism we studied 29 patients with mitral valve prolapse, including nine (group I) with thromboembolism (cerebral, retinal and deep venous), eight (group II) with transient visual obscurations and 12 (group III) with neither thromboembolism nor visual complaints, compared with 18 control patients and 38 normal subjects. Patients in groups I and II had increased platelet coagulant activities concerned with the initiation and early stages of intrinsic coagulation, and group I patients had an increased proportion of circulating platelet aggregates and platelets relatively insensitive top epinephrine in aggregation and secretion. The incidence of platelet coagulation hyperactivity in patients with mitral valve prolapse was 76% (100% in group I, 75% in group II, 58% in group III), compared with 6% in control patients. These results suggest that platelets play a role in the purported association of thromboembolism and mitral valve prolapse.