Aortic valve replacement with the freestyle stentless bioprosthesis: five-year experience.
BACKGROUND
Stentless aortic valves were designed to provide a more physiological flow pattern and lower transvalvular gradient, which may have an important bearing on postoperative left ventricular function and remodeling. In this study, we prospectively analyzed the 5-year clinical results with the Freestyle valve (Medtronic, Inc) and its hemodynamic performance by serial echocardiography.


METHODS AND RESULTS
Between January 1993 and August 1997, 95 patients with a mean age of 75 years underwent aortic valve replacement with the Freestyle prosthesis. Sixty-four percent of patients received valves </=23 mm, and 37% had concomitant coronary artery bypass grafting. Average follow-up was 44+/-18 months (mean+/-SD), and echocardiography was performed preoperatively, at discharge, at 3 to 6 months, and annually thereafter. The 30-day operative mortality rate was 3%, with an overall actuarial survival rate of 80+/-6% (mean+/-SEM) at 5 years. Of the 10 late deaths, only 2 were cardiac related, thereby yielding a freedom from cardiac mortality of 94+/-3% after 5 years. No patient required reoperation on the aortic valve for any reason, including structural degeneration, nonstructural dysfunction, or prosthetic valve endocarditis. There were 9 thromboembolic and 3 anticoagulant-related bleeding events, none of which was fatal. The actuarial freedom from valve-related morbidity and mortality was 79+/-4% at 5 years. Hemodynamically, the mean transvalvular gradient significantly decreased after valve replacement and was reduced further by 41% by 6 months with a corresponding increase in effective orifice area. Left ventricular mass index fell to 75% of the preoperative value by 2 years.


CONCLUSIONS
The Freestyle stentless valve can be implanted safely in the elderly with excellent midterm clinical results. It has superb hemodynamics in terms of residual transvalvular gradient, effective orifice area, and regression of left ventricular hypertrophy.