Objective: We performed a multi-institutional study to compare the long-term structural valve deterioration of isolated Hancock Standard versus Hancock II bioprostheses.
Methods: From 1983 to 2002, 714 Hancock Standard and 1293 Hancock II bioprostheses were implanted at hospitals of the Venetian territory (Padova, Treviso, and Venice). Follow-up on January 1, 2003, included 14,749 patient-years with a median of 12 years and was 96% complete: 115 Hancock Standard and 53 Hancock II bioprostheses were at risk at 15 years. The 2 series were nonconcomitant, and many covariates differed (Table 1). Survival was analyzed with Cox analysis, and durability was analyzed with Weibull analysis. Balancing analysis with the logistic propensity score model was performed.
Results: Perioperative mortality was 6% in Hancock II and 12% in Hancock Standard operations. The overall unadjusted 15-year survival was identical (39.7% +/- 2.3% vs 39.9% +/- 2.4%, respectively), but age-adjusted survival at 15 years was 46% versus 25% (P < .001). Late survival was unrelated to the prosthetic model, whereas it was adversely affected by older age, previous operations, aortic regurgitation, male sex, higher New York Heart Association class, atrial fibrillation, and coronary artery bypass grafting. In Hancock II patients aged 65 years and older, the cumulative hazard of structural valve deterioration at 15 years was 6%, versus 17.5% in Hancock Standard patients. In younger patients, it was 18% and 37%, respectively. Analysis of 541 propensity-balanced patients showed a hazard ratio of the Hancock Standard prosthesis of 2 and a risk reduction of older age of approximately 10% every 10 years.
Conclusion: After balancing risk factors and calibrating age effects, Hancock II propensity-matched bioprostheses showed similar survival but definitely increased durability.