Dipyridamole-aspirin as thromboembolic prophylaxis in patients with aortic valve prosthesis. Prospective study with the Model 2320 Starr-Edwards prosthesis.

In a prospective study, the efficacy of a dipyridamole-aspirin regimen in prevention of thromboembolism was evaluated in 50 patients having isolated aortic valve replacement with the Model 2320 Starr-Edwards prosthesis. These operations were performed between February, 1972, and October, 1974. In 1,380 patient-months of follow-up, there was a 20% incidence of thromboembolism with a rate of 8.7/100 patient-years and a 19% probability of an embolic episode occurring by 3 years. Seven patients had transient episodes, two had permanent neurologic residua, and one patient died. Comparison is made to a similar group of patients having solitary aortic valve replacement but receiving no medication, studied by Starr and associates. There was no statistical difference in the incidence of thromboembolism between the two groups. In November, 1975, all patients were converted to a regimen of warfarin therapy. Since conversion to anticoagulation, there have been two thromboembolic episodes in 2,132 patient-months of follow-up for a rate of 1.1/100 patient-years. We conclude that the use of antiplatelet therapy in the form of dipyridamole-aspirin is inadequate for routine thromboembolic prophylaxis following SE 2320 aortic valve replacement.