SHOULD PATIENTS WITH BJORK-SHILEY VALVES UNDERGO PROPHYLACTIC REPLACEMENT

About 85 000 patients have undergone replacement of diseased heart valves with prosthetic Bjork-Shiley convexo-concave (CC) valves. These valves are prone to fracture of the outlet strut, which leads to acute valve failure that is usually fatal. Should patients with these valves undergo prophylactic replacement to avoid fracture? The incidence of strut fracture varies between 0% and 1.5% per year, depending on valve opening angle (60-degrees or 70-degrees), diameter (<29 mm or greater-than-or-equal-to 29 mm), and location (aortic or mitral). Other factors include the patient's life expectancy and the expected morbidity and mortality associated with reoperation. We have used decision analysis to identify the patients most likely to benefit from prophylactic reoperation. The incidence of outlet strut fracture was estimated from the data of three large studies on CC valves, and stratified by opening angle, diameter, and location. A Markov decision analysis model was used to estimate life expectancy for patients undergoing prophylactic valve replacement and for those not undergoing reoperation. Prophylactic valve replacement does not benefit patients with CC valves that have low strut fracture risks (60-degrees aortic valves and <29 mm, 60-degrees mitral valves). For most patients with CC valves that have high strut fracture risks (greater-than-or-equal-to 29 mm, 70-degrees CC), prophylactic valve replacement increases life expectancy. However, elderly patients with such valves benefit from prophylactic reoperation only if the risk of operative mortality is low. Patient age and operative risk are most important in recommendations for patients with CC valves that have intermediate strut fracture risks (<29 mm, 70-degrees valves and greater-than-or-equal-to 29 mm, 60-degrees mitral valves). For all patients and their doctors facing the difficult decision on whether to replace CC valves, individual estimates of operative mortality risk that take account of both patient-specific and institution-specific factors are essential.