Long-term results of Freestyle stentless bioprosthesis in the aortic position: A single-center prospective cohort of 500 patients

Objective: Stentless xenograft bioprostheses may be the future valve of choice for aortic valve replacement. The study aim was to investigate the long-term clinical outcome after aortic valve replacement with the Medtronic Freestyle bioprosthesis (Medtronic Inc, Minneapolis, Minn). Methods: Between April 1997 and November 2004, a total of 500 patients (mean age, 74.5 +/- 9.6 years; 52% were male) underwent aortic valve replacement with a Freestyle bioprosthesis, without population selection. The surgical procedure used a modified subcoronary technique in 479 patients and a complete root replacement in 21 patients, conducted with mini-extracorporeal circulation. Concomitant procedures included coronary artery bypass grafting in 122 patients (24%) and mitral valve repair/replacement in 11 patients. Results: The mean cardiopulmonary bypass time was 98 +/- 26 minutes, and total aortic crossclamp time was 77 +/- 19 minutes. Operative mortality was 5.2%. The median follow-up time was 104.8 +/- 5.7 months. During this period, there were 224 deaths (n = 122 cardiovascular and n = 102 noncardiovascular deaths). The actuarial survivals from cardiovascular and valve-related mortality were 67% +/- 3% and 70% +/- 4%, respectively, at 10 years. Freedom from structural valve deterioration at 10 years was 94% +/- 2%. The linearized structural valve deterioration incidence was 0.6% per patient/year. Multivariate Cox regression analysis revealed that older age, impaired renal function, and coronary artery disease were independent predictors of cardiovascular death. In the subgroup of patients aged less than 65 years at implantation (n = 45), the actuarial cardiovascular survival was 83% +/- 8% and freedom from structural valve deterioration was 89% +/- 6% at 10 years. Conclusions: The use of the Freestyle bioprosthesis for aortic valve replacement resulted in good long-term cardiovascular survival and freedom from structural valve deterioration in this cohort regardless of age at implantation.