Experience with moderate intensity anticoagulation and aspirin after mechanical valve replacement. A retrospective, non-randomized study.

: A selected group of patients who underwent valve replacement were analyzed to evaluate the feasibility, effectiveness and safety of combined treatment with moderate intensity anticoagulation plus aspirin. One hundred ninety-six patients who received a total of 204 mechanical valve prostheses between 1985 and 1991 were selected according to rigid criteria. The prostheses included 124 valves of caged ball design, 62 St. Jude valves and 18 others. The follow up of the whole population was 581.8 patient years, with an average of 2.97 patient years, and was complete by the definition criteria. All patients received moderate intensity anticoagulation with acenocoumarol (target International Normalized Ratio 2.5 to 3.5) and daily aspirin (100 mg or 325 mg). The incidence of thromboembolic events for the whole group was 3.26% per patient year, but only 1.6% in patients "compliant" with treatment. Preoperative embolism and non-compliance with treatment had a strong correlation with postoperative thromboembolism. The INR values had a strong correlation with both thromboembolic and hemorrhagic events. The incidence of serious hemorrhagic events was 4.12% patient years although only two cases (0.34%/pty) were fatal (cerebral hemorrhages). There was no difference in hemorrhagic incidence between patients receiving either 325 mg or 100 mg daily. A low incidence of thromboembolic complications was attained with the use of combined antithrombotic and antiplatelet therapy, even in the first generation caged ball type prostheses. However, the combination of moderate intensity anticoagulation with either 325 mg or 100 mg aspirin was associated with a risk of bleeding similar to high intensity anticoagulation alone. The risk of bleeding appeared to be greater in the presence of gastric pathology, and the combination of anticoagulants and aspirin should be avoided in patients with these conditions.