Effect of stent mounting on tissue valves for aortic valve replacement

Stent mounting of homograft valves was first reported by our group in 1968. Since then, there has been question as to whether or not stent mounting of bioprostheses adversely affects the incidence of structural deterioration in aortic valve replacement. Between November 1967 and July 1988, 571 consecutive patients underwent valve replacement with a stented or unstented homograft. There were 351 men (61.5%) and 220 women (38.5%). The mean age of the group was 49.2 years (range 18 to 79 years). Five hundred thirty-four patients left the hospital (30-day overall mortality 6.5%). Follow-up extends from 6 months to 22 years with a mean of 7.6 years. The cumulative follow-up for the series was 4,095.9 patient-years. Hospital mortality, early technical failure, and prosthetic valve endocarditis were considered censoring events and excluded from this study. Actuarial analysis revealed a significant difference (p less than 0.02) in the freedom from structural valve deterioration for unstented and stended isolated aortic valve replacement. Age (50 and under, and over 50) does not appear to be a factor in structural deterioration in unstented homografts but does influence the rate of failure in stented homografts (p less than 0.05). These results clearly indicate that stent mounting adversely affects tissue valve durability with aortic valve replacement. Moreover, age correlates with structural deterioration if valves are stented and does not if they are unstented. Based on these results, the use of unstented bioprostheses should be reevaluated, along with the design of porcine valve stents.