SP740MECHANICAL VERSUS BIOPROSTHETIC HEART VALVES: A COMPARISON STUDY IN END-STAGE RENAL DISEASE

Abstract

Introduction and Aims: Little evidence guides the choice of valve replacement in patients with end-stage renal disease (ESRD) patients; meta-analyses suggest no survival difference between bio- and mechanical prostheses. Current AHA/ACC guidelines make no specific recommendations, having previously advocated the use of metallic valves in such patients owing to the risk of accelerated calcification of tissue valves. The use of metal valves necessitates life-long anticoagulation, usually with warfarin. It is increasingly recognised that ESRD patients have significant increased bleeding risk, and that warfarin should be avoided.We examined outcomes in such patients with both bio- and mechanical valve replacements. Methods:We retrospectively studied all patients known to our services with ESRD and a valve replacement.We gathered demographics from the time of replacement and data on anticoagulation, including time in the therapeutic range (TTR). TTR was calculated using the Rosendaal linear interpolation method, giving a percentage of days and results within the therapeutic target (target TTR should be >65%).We noted outcomes including major bleeding, endocarditis, tissue valve redo and mortality. Results:We included 82 patients; 43 metal valves, 39 tissue. A total of 419 patient-at-risk years were examined. Median age at replacement was 58 years. 62% were male and 23% diabetic. 39% had been identified as having ischaemic heart disease and 23% had simultaneous coronary artery bypass-grafting. The majority of valves were aortic (68%). All patients with metal valves were anticoagulated with warfarin, 3 with concomitant aspirin. 5 patients with tissue valves took warfarin because of AF and 21 were on aspirin. TTR for warfarinised patients was 37% days in range, 36% results in range. 63% of patients with a metal valve and 59% with a tissue valve were on haemodialysis or peritoneal dialysis at the time of operation. There were 44 major bleeding events (2 fatal) across 24 patients with metal valves, versus 9 with tissue; a bleed rate of 19.6 versus 4.6 per 100-patient-years (p=0.004). Endocarditis rates were higher in metal valves (23% vs 10%, p=0.05). Median time before death was 5.7yrs in metal valves and 3.6 in tissue. 3 warfarinised patients developed calciphylaxis (2 fatal). 3 patients with tissue valves required redo operations (1 paediatric valve, 2 due to endocarditis). Echo reports suggested no significant accelerated calcification in any of the tissue valves. Conclusions: The main indication formetal valves is in younger patients where tissue valve lifespan must be considered. Poor 5 year survival in ESRD makes this less relevant. The likelihood of future procedures (vascular access, transplantation, biopsy) in a population at increased risk of major bleeding makes anticoagulation hazardous.We demonstrate increased major bleeding, endocarditis and calciphylaxis with metal valves with no valve-survival advantage, suggesting metal valves should be avoided in ESRD.