Use of stentless xenografts in the aortic position: determinants of early and late outcome

Background. Whether to perform a stentless aortic valve replacement (AVR) is not well established. Our aim was to determine the outcome after AVR with stentless xenograft valves. Methods. Between 1996 and 2001, a total of 404 patients (mean age 70.4 years) underwent a stentless AVR by one surgeon in our unit. Concomitant procedures were performed in 132 patients (33%). Twenty patients (6.4%) had undergone previous AVR. Eleven types of stentless xenograft valves were implanted: Medtronic Freestyle in 221 patients (55%), Shelhigh in 55 (14%), Shelhigh composite conduit in 33 (8%), Sorin in 26 (6%), Cryolife O‘Brien in 25 (6%), Aortech-Elan in 17 (4%), Edwards Prima in 14 (4%), Toronto SPV in 7 (2%), and other valves in 6 (1%). A subcoronary implantation technique was used in 302 cases (76%), complete root replacement in 62 (15%), and a modified Bentall-De Bono procedure in 33 (8%). Mean follow-up was 19.4 months (range, 1.2 to 60.6 months). Results. Overall hospital mortality was 4.2%. This was 2.4% for isolated AVR, 3.6% for AVR and coronary artery bypass grafting, 5.5% for replacement of two or more valves, and 12% for the modified Bentall procedure. On multiple logistic regression redo cardiac operation (p = 0.0006), cardiogenic shock (p = 0.001), left ventricular ejection fraction less than 0.30 (p = 0.01), modified Bentall procedure (p = 0.03), and endocarditis (p = 0.04) were predictors of in-hospital death. Five-year freedom from thromboembolism, hemorrhage, prosthetic endocarditis, structural valve deterioration, and reoperation was 97%, 99%, 99%, 98%, and 96%, respectively. Kaplan-Meier survival at 5 years was 88%. On Cox regression, cardiogenic shock (p = 0.001) and older age (p = 0.03) were adverse predictors of survival. At echocardiographic examination within 6 months from the operation, mean aortic valve gradients were 15 ± 6 mm Hg, 12.8 ± 3 mm Hg, 10.8 ± 4 mm Hg, 9.3 ± 3 mm Hg, 9.1 ± 4 mm Hg, and 8.2 ± 3 mm Hg for valve sizes of 19, 21, 23, 25, 27, and 29 mm, respectively. Conclusions. The availability of several stentless valve designs facilitates the surgical treatment of diverse aortic valve or root diseases with encouraging early and midterm results. Patients requiring concomitant procedures may also benefit from the excellent hemodynamic characteristics of a stentless valve. We consider stentless AVR the treatment of choice for patients older than 60 years and those having small aortic roots.