PLATELET INHIBITION AFTER CARDIAC-VALVE REPLACEMENT

After implantation of a mechanical cardiac valve, lifelong, full antic oagulation has been the tradition. After implantation of a biological valve, anticoagulation during 3 months subsequent to the operation is customary. This review evaluates the role of platelet inhibition after cardiac valve replacement. Platelet aggregation is inhibited effectiv ely by aspirin in a daily dose of 100 - 160 mg. At this dose, episodes of severe bleeding are not significantly more frequent than during pl acebo, whereas patients on full anticoagulation bleed at a rate of 2% per year. After implantation of a mechanical cardiac valve, sole plate let inhibition is inferior to full anticoagulation. With a lower rate of bleeding, aspirin appears to prevent thromboembolic episodes caused by mechanical bileaflet prostheses (e.g., St. Jude) in the aortic pos ition, and is almost as efficient as full anticoagulation. In Germany, patients with a porcine bioprosthesis, as currently in use, in the ao rtic position, frequently receive 100 mg aspirin per day. For patients with porcine bioprostheses in the mitral plus eventually in the aorti c position in stable sinus rhythm, 100 mg aspirin per day is preferred to anticoagulation. For children with mechanical aortic valves, aspir in (2 mg/kg/day) needs to be considered an effective and convenient al ternative to anticoagulation. Combining anticoagulation with 100 mg as pirin per day after implantation of a left-sided mechanical cardiac va lve is pathophysiologically sound, but used to be considered as render ing the patients too bleeding-prone. Recently, total mortality and mor bidity definitely have been demonstrated to be reduced by combined ant icoagulation and platelet inhibition as compared to sole anticoagulati on. Combining platelet inhibition with moderate anticoagulation (INR 2 .0 - 3.0) was superior to combining it with full anticoagulation in te rms of safety (INR > 3.0). Thus, current evidence favors combining mod erate anticoagulation with 100 mg aspirin per day after left-sided mec hanical cardiac valve replacement.