Long-term results of mitral valve replacement: biological xenograft versus mechanical valves

Abstract

We studied 279 patients who underwent mitral valve replacement at the Department of Thoracic and Cardiovascular Surgery, Hyogo College of Medicine, between November 1973 and December 1998. The patients were divided into two groups based on the type of replacement valve (154 patients in the biological xenograft group and 125 patients in the mechanical valve group), and the long-term results were compared. Clinically satisfactory results were obtained in both the biological xenograft group and the mechanical valve group according to the surgical results, long-term survival, and incidence of prosthetic valve endocarditis. At 15 years, fewer patients in the mechanical valve group than in the biological xenograft group were free of bleeding events (92.5 +/- 3.7% vs 100% P < 0.05). At 15 years, the biological xenograft group was lower than the mechanical valve group with respect to freedom from thromboembolism (72.2 +/- 4.6% vs 93.5 +/- 3.6% P < 0.01), freedom from valve failure (22.0 +/- 5.2% vs 87.0 +/- 4.1% P < 0.005) and freedom from cardiac events (16.5 +/- 3.9% vs 47.2 +/- 14.5% P < 0.01). Though it has previously been suggested that biological xenografts used in mitral valve replacement do not need anticoagulation, the current study suggests the need for anticoagulation with the use of biological xenografts. Mechanical valves require close monitoring of anticoagulation, but their use has decreased the incidence of valve failure and thromboembolism, as compared with the use of biological xenografts. Therefore, mechanical valves are currently the preferred choice for mitral valve replacement. We believe that biological xenografts are indicated only for the older patient (> or =65 years).

Long-term outcome after mitral valve replacement using biological versus mechanical valves

“…Earlier studies report that mechanical valves were associated with increased durability [2, 5, 6]. The KM data confirm that at 10 years patient survival is higher with the mechanical valve than the biological valve (77.1% vs. 62.4%, respectively), despite survival being nominally higher with the biological valve within the first years of follow-up.…”

“…Both types of valves have advantages and disadvantages, but also specific patient factors need to be taken into consideration when making the decision on which valve type to use [9, 10]. Historically, biological MVs were generally considered to have superior antithrombotic properties but lacked durability, while mechanical valves were thought to be more durable but were associated with thromboembolism and bleeding events [2, 5, 6, 9]. The data from our study confirm the observation that the use of anticoagulation along with mechanical valve implantation is associated with an increased risk of bleeding and that there is a potential survival benefit for patients receiving a biological MV.…”

“…Biological MVs are generally considered to be associated with lower bleeding complications due to the need for less or no anticoagulation, but they lack of durability. Mechanical valves are durable, but are associated with thromboembolism and bleeding complications mostly because of inevitable lifelong anticoagulation therapy [2, 5, 6].…”

“…After 15 years, fewer patients in the mechanical valve group were free of bleeding events (92.5% vs. 100%) and patients in the biological valve group had a lower freedom from thromboembolism (72.2% vs. 93.5%), valve failure (22.0% vs. 87.0%) and cardiac events (16.5% vs. 47.2%). The study concluded that the use of mechanical valves was preferential and biological valves should be reserved for patients older than 65 years and only be used with concomitant anticoagulant therapy [5]. Conversely, the results of a 10-year follow-up study published in 2001 showed no significant clinical differences between patient groups receiving biological and mechanical valves [7].…”

Outcomes of Patients Undergoing Third-Time Aortic or Mitral Valve Replacement

“…There is an increasing number of studies dealing with comparisons between mechanical and biological valves regarding risk and benefits, valve‐related complications, and quality of life . Valve replacement with mechanical prostheses has demonstrated excellent freedom from re‐operations but exhibits a high rate of morbidity and mortality related to hemorrhage or thromboembolic events .…”