Porcine valve durability : a comparison between Hancock standard and Hancock II bioprostheses. Discussion

Two series of patients who received a Hancock standard (HS) (1970 to 1983) and a Hancock II (HII) (1983 to 1992) porcine bioprosthesis were reviewed to compare bioprosthetic durability. Patients with HS porcine bioprostheses (n = 769) differed from those with HII bioprostheses mostly in mean age at operation (47 ± 12 versus 62 ± 9 years ; p < 0.001) ; the latter prosthesis was implanted mostly in patients older than 50 years. At 8 years after operation, actuarial survival was 57% ± 4% after aortic, 61% ± 3% after mitral, and 39% ± 7% after mitral-aortic valve replacement with the HS bioprosthesis ; actuarial survival was 51% ± 9% after aortic, 66% ± 6% after mitral, and 49% ± 10% after mitral and aortic valve replacement with an HII bioprosthesis. No cases of structural deterioration of HII bioprostheses were observed at 8 years in any patients. Actuarial freedom from structural valve deterioration was 78% ± 4% after aortic, 88% ± 3% after mitral, and 79% ± 7% after mitral-aortic valve replacement with an HS bioprosthesis at 8 years. In all patients greater than 50 years of age, actuarial freedom from structural valve deterioration at 8 years was 90% ± 3% in patients with an HS bioprosthesis and 100% in those with an HII bioprosthesis (p = 0.08). A trend to an improved durability of the HII bioprosthesis compared with the HS was observed during the first 8 postoperative years. Because these results could be influenced partly by the age difference in the two series of patients, a longer follow-up is needed to confirm these data.