Tilting-disc versus bileaflet mechanical prostheses in the aortic position: a multicenter evaluation.

During the four decades since implantation of the first aortic valve prosthesis, aortic valve replacement (AVR) has become standard therapy. Since 1960, 70 different mechanical valve models have been introduced into clinical practice and implanted in humans, with the aim of improving the performance of mechanical valves. All of these valves have been classified into three groups according to their design features and time of release onto the market. The three groups are ball valves, tilting-disc valves, and bileaflet valves. The ball valves, or first-generation mechanical prostheses, were the first valve models to be implanted in routine clinical practice (1). Subsequently, the second generation of mechanical valves was launched the tiltingdisc valves (2). In 1977, implantation of the first St. Jude Medical valve opened the way to the third-generation, or bileaflet, valves (3). At the present time, the bileaflet valve is the dominant modern design for the mechanical heart valve prosthesis (4), mainly because it is generally perceived that the more ‘modern’ prosthetic device possesses an enhanced clinical performance. However, controversy persists as to whether bileaflet valves have a better long-term performance compared with tilting-disc valves. The aim of the present study was to assess, in a multicenter experience, whether this assumption holds true over the long term.