Late results of mitral and aortic valve replacement.

Experience with isolated mitral and aortic valve replacement at the University of Oregon Medical School since 1965 is presented. Results with non-cloth-covered and cloth-covered valves were analyzed with actuarial techniques and were compared in terms of late survival, thromboembolic complication rate, reoperation rate and the influence of anticoagulation therapy. The cloth-covered prostheses have substantially lowered the incidence of emboli after mitral replacement, and have thus far eliminated emboli after aortic replacement in patients receiving warfarin. Although anticoagulation therapy is still necessary, a clinical trial is currently in progress to assess the adequacy of antiplatelet drugs. The choice of a cloth-covered or non-cloth-covered valve should be individualized for each patient, based on the different risks and benefits of each prosthesis.