Antiplatelet Therapy for Long-Term Management of Patients with Mechanical Aortic Prostheses

A mechanical aortic prosthesis (MAP) may cause platelet activation secondary to shear forces, and the release of adenosine diphosphate (ADP). This platelet-mediated event may lead to arterial embolism. Traditionally, warfarin has been used to treat such cases, although this anticoagulant has no inhibitory effects on platelets. The study aim was to determine if antiplatelet agents could prevent thromboembolic events in patients with a MAP.

Since 2001, a total of 265 patients (average age 64.5 ± 12.0 years), each of whom received a MAP with or without additional aortic surgery, was followed at the authors' institution. Patients received a loading dose of clopidogrel or prasugrel + asprin 325 mg and tested for platelet inhibition. The maintenance dose was 75 mg clopidogrel or 10 mg prasugrel + 81 mg aspirin. Platelet reactivity was tested, using two different methods, after one month and at six-month intervals thereafter.

The average follow up was 47.3 ± 44.3 months; total follow up was 11,688.8 months [974 patient-years (pt-yr)]. Over a 16-year period 51 patients died, primarily from myocardial infarction. Twelve patients had strokes (1.2%/pt-yr); of these patients, 10 had discontinued the antiplatelet medication (and were receiving warfarin). One patient was nonresponsive to clopidrogel and another (a compliant patient) was never tested. Strokes were not observed in compliant patients who responded to antiplatelet agents. Thirteen patients had gastrointestinal bleeding, four required transfusion, and three died due to cerebral aneurysms.

Platelet-mediated thromboembolism following MAP installation can be treated with antiplatelet agents. The 16-year results of the present study suggested that antiplatelet agents can reduce thromboembolic events in patients with MAP. Strokes can be prevented in patients with MAP if treated with the correct antiplatelet agent, if the patient responds to the agent employed and is strictly compliant.