Stentless bioprosthetic valve produces better exercise hemodynamics and greater regression of left ventricular hypertrophy when used in the aortic position. They have a better orifice size for a given annular size. Hence they are suited for those patients with aortic stenosis and a small aortic annulus. The other option in case of small annular size in aortic stenosis is aortic root widening procedure.
Six year results of Toronto SPV (stentless porcine valve) bioprosthesis was reported in 1999 . There were 635 patients in the age range of 33 to 93 years. At 6 years, the actuarial survival was 82.6%. The mean systolic gradient was only 5 mmHg and 81% were free of cardiac symptoms. 85% did not have aortic regurgitation and there were no primary tissue failures.
Long term data on Freestyle stentless bioprosthesis is also available . Between 1993 and 2013, 531 patients underwent implantation of Freestyle stentless bioprosthesis either with or without aortic root reconstruction. Freedom from reoperation for structural valve degeneration 94.6% and 76.7% at 10 and 15 years, respectively, in those who did not undergo aortic root reconstruction. In those who underwent aortic root reconstruction also, it was 98.9% and 88.1% at 10 and 15 years, indicating a better result for those who underwent aortic root reconstruction as well. But the difference in techniques did not influence in hospital or long term mortality.
Bach DS et al  have also reported on the long results (15 years) of Freestyle stentless bioprosthesis. 402 males and 323 women had a total follow up of 5,491.2 patient-years. Ten and 15 year survivals were around 46% and 26% respectively. Freedom from valve related death was around 95% and 93% respectively. Increased age was associated with higher mortality, but lower risk of reoperation and explant due to structural valve degeneration, as expected.
- David TE. The Toronto SPV bioprosthesis: clinical and hemodynamic results at 6 years. Ann Thorac Surg. 1999 Sep;68(3 Suppl):S9-13.
- Mohammadi S, Kalavrouziotis D, Voisine P, Dumont E, Doyle D, Perron J, Dagenais F. Bioprosthetic valve durability after stentless aortic valve replacement: the effect of implantation technique. Ann Thorac Surg. 2014 Jun;97(6):2011-8.
- Bach DS, Kon ND. Long-term clinical outcomes 15 years after aortic valve replacement with the Freestyle stentless aortic bioprosthesis. Ann Thorac Surg. 2014 Feb;97(2):544-51.