Late Outcomes of Aortic Valve Replacement with Bioprosthesis and Mechanical Prosthesis

Abstract Background Despite constant improvement and refinement of the prostheses, the decision between mechanical and biological valves for aortic valve replacement is still controversial. Objective To compare outcomes of aortic valve replacement with bioprosthesis and mechanical prosthesis. Methods This was an observational, historical cohort study with review of medical records. A total of 202 patients who underwent heart valve replacement surgery between 2004 and 2008 were selected, with a mean follow-up of 10 years. The level of significance set at 5%. Results Mean age of patients was approximately 50 years; most patients were male (70%). Overall mortality- and reoperation-free survival was significantly higher in patients with mechanical prosthesis (HR=0.33; 95%CI=0.13-0.79; p=0.013). No difference was found in late mortality between the two groups. On the other hand, the risk of reoperation was significantly higher in patients with bioprosthesis than mechanical prosthesis (HR=0.062; 95%CI=0.008-0.457; p=0.006). The risk of composite adverse events – stroke, bleeding, endocarditis, thrombosis and paravalvular leak – was similar between the groups (HR=1.20; 95%CI= 0.74-1.93; p=0.44). The risk of bleeding was significantly higher in patients with mechanical prosthesis (HR=3.65; 95%CI= 1.43-9.29; p = 0.0064), although no case of fatal bleeding was reported. Conclusion No difference in 10-year mortality was found between the groups. The risk of reoperation significantly increases with the use of bioprosthesis, especially for patients younger than 30 years. Patients with mechanical prosthesis are at increased risk of nonfatal bleeding.

摘要
背景 尽管人工心脏瓣膜（prostheses）的性能持续优化与精进，在主动脉瓣置换术（aortic valve replacement）中选择机械瓣膜（mechanical prosthesis）还是生物瓣膜（biological prosthesis）的临床决策仍存在争议。
目的 比较主动脉瓣置换术中使用生物瓣膜与机械瓣膜的临床结局。
方法 本研究为回顾性观察队列研究（observational historical cohort study），采用病历回顾分析（review of medical records）的方式。共纳入2004年至2008年间接受心脏瓣膜置换手术的202例患者，平均随访时长为10年，设定显著性检验水准为5%。
结果 患者的平均年龄约为50岁，其中多数为男性（占比70%）。机械瓣膜组患者的总体无死亡及无再手术生存率显著更高（风险比hazard ratio, HR=0.33；95%置信区间95% confidence interval, 95%CI=0.13~0.79；p=0.013）。两组患者的晚期死亡率无显著差异。另一方面，生物瓣膜组患者的再手术风险显著高于机械瓣膜组（HR=0.062；95%CI=0.008~0.457；p=0.006）。两组患者的复合不良事件（composite adverse events）——包括脑卒中（stroke）、出血（bleeding）、心内膜炎（endocarditis）、血栓形成（thrombosis）及瓣周漏（paravalvular leak）——的发生风险无显著差异（HR=1.20；95%CI=0.74~1.93；p=0.44）。机械瓣膜组患者的出血风险显著更高（HR=3.65；95%CI=1.43~9.29；p=0.0064），但未出现致死性出血病例。
结论 两组患者的10年死亡率无显著差异。使用生物瓣膜的患者再手术风险显著升高，尤其针对30岁以下的患者。机械瓣膜组患者的非致死性出血（nonfatal bleeding）风险有所增加。