Eight-year results of Freestyle stentless bioprosthesis in the aortic position: a single-center study of 500 patients

BACKGROUND AND AIM OF THE STUDY: Stentless bioprostheses may be the future valve of choice for aortic valve replacement (AVR). The study aim was to investigate mid-term clinical outcome after AVR with the Medtronic Freestyle valve. METHODS: Between April 1997 and November 2004, a total of 500 patients (241 females, 259 males) was implanted with a Freestyle bioprosthesis for AVR, without population selection, by a single surgical team at the authors' institutions. Mean patient age was 74.5 +/- 9.6 years (range: 26-91 years); 34 patients (7%) were aged < 60 years, 121 (24%) were aged > 80 years, and 205 (41%) were in NYHA classes III or IV. The surgical procedure used included a modified subcoronary technique in 482 cases and complete root replacement in 18, conducted with mini-extracorporeal circulation. Concomitant procedures included coronary artery bypass grafting in 123 patients (25%), mitral valve repair/replacement in five, and maze in two. Follow up was 98% complete; the mean follow up was 31.3 months (range: 4-95 months). RESULTS: The mean cardiopulmonary bypass time was 98 +/- 26 min, and total aortic cross-clamp time 77 +/- 19 min. Operative mortality was 5.2% (n = 26), and no patients aged under 60 years died. At eight years, freedom from structural valve deterioration was 100% (0% in the young population), freedom from endocarditis 97.2%, freedom from reoperation 97%, and overall survival 83%. Most of the late deaths (n = 56) were of non-cardiac origin, and occurred in older patients. After one year, the mean aortic echocardiographic gradient was 11.5 +/- 1.1 mmHg, and was improved compared to that at discharge. No significant aortic insufficiency occurred. CONCLUSION: Use of the Freestyle stentless bioprosthesis for AVR resulted in excellent short-term survival in the octogenarian population, and excellent mid-term results in the younger population. In time, experience will indicate whether the Freestyle should be considered as the bioprosthesis of choice for patients of all ages.