Aim. Improved hemodynamics with stentless bioprosthesis compared to stented. valves have been well documented. it has been suggested that a simplified implant model, the Cryolife-O'Brien, offers less satisfactory outcomes compared with standard stentless models. This study was conducted to prospectively evaluate the midterm results after aortic valve replacement with the Cryolife-O'Brien stentless bioprosthesis. Methods. In 1996, the prospective clinical trial using different stentless valves was initiated in our center. From September 1996 through August 2001, 132 consecutive patients with a mean age of 72.5 years underwent aortic valve replacement with the Cryolife-O'Brien porcine stentless bioprosthesis by the same surgeon. The predominant aortic valve lesion was stenosis in 110 cases and insufficiency in 22 cases. Patients have been followed-up from 2 to 60 months, mean 28 months. Echocardiography was performed by the same echocardiographer preoperatively, intraoperatively, postoperatively at discharge, 2 to 6 months later and annually thereafter. Results. Sixty-five percent of patients received a valve 25 mm in diameter or larger, 42% had concomitant coronary bypass grafting. The 30-day operative mortality rate was 6.8%. Nine late deaths, none related to the valve, have occurred. Severe aortic insufficiency caused by oversizing led to early reoperation in 3 patients. The peak and mean systolic gradients decreased significantly during the first 12 months after implantation (p < 0.001) and the effective valve areas increased significantly during this time interval (p < 0.001). Eleven patients have aortic insufficiency, trivial in 7 and mild in 4. The actuarial survival at 5 years was 86 +/- 3%. The rate for freedom from endocarditis was 100% and for freedom from thromboembolic events 92%. Conclusion. The Cryolife-O'Brien stentless bioprosthesis has superior hemodynamics and a low rate of valve-related complications thus representing a very good alternative to conventional stented bioprosthesis. The midterm results are encouraging but further follow-up is needed to determine the valve's durability.
