Prosthetic valve type for patients undergoing aortic valve replacement: A decision analysis

Background. In two large, randomized, clinical trials long-term survival af ter aortic valve replacement (AVR) was similar for patients receiving tissu e and mechanical aortic heart valve prostheses. Higher bleeding rates among patients with mechanical valves, who must receive permanent oral anticoagu lation to prevent thromboembolism, were offset by higher reoperation rates for valve degeneration among patients with tissue valves. Because the avera ge age of patients undergoing AVR and clinical practices have changed consi derably since the randomized clinical trials were conducted, we performed a decision analysis to reassess the optimal valve type for patients undergoi ng AVR. Methods. We used a Markov state-transition model to simulate the occurrence of valve-related events and life expectancy for patients undergoing AVR. p robabilities of clinical events and mortality were derived from the randomi zed clinical trials and large follow-up studies. Results. Although the two valve types were associated with similar life exp ectancy in 60-year-old patients (mean age of patients; in the randomized cl inical trials), tissue valves were associated with greater life expectancy than mechanical valves (10.7 versus 11.1 years) in 70-year-old patients (cu rrently mean age of AVR patients). For 70-year-old patients, the effects of major bleeding complications (24%) with mechanical valves substantially ou tweighed those of reoperation for valve failure (12%) with tissue valves at 12 years. Of the clinical practice changes assessed, the recommended valve type was most sensitive to changes in bleeding rates with anticoagulation. However, bleeding rates would have to be 68% lower than those reported in the European randomized clinical trial to affect the recommended valve type for 70-year-old patients. Reoperation rates would have to be five times hi gher, and mortality rates at reoperation would have to be four times higher to affect the recommended valve type for 70-year-old patients. Conclusions. Although mechanical valves are preferred for AVR patients less than 60 years old, most patients currently undergoing AVR are elderly and would benefit more from tissue valves. (Ann Thorac Surg 2000;70:1946-52) (C ) 2000 by The Society of Thoracic Surgeons.