Postoperative lipid-lowering therapy and bioprosthesis structural valve deterioration: justification for a randomised trial?

Objective: Bioprosthesis structural valve deterioration (SVD) is an incompletely understood process involving the accumulation of calcium and lipids. Whether this process could be delayed with lipid-lowering therapy (LLT) is currently unknown. The purpose of this observational study was to evaluate if an association exists between early LLT and a slowing of bioprosthesis SVD, with a view to designing a prospective trial. Methods: We followed 1193 patients who underwent aortic valve replacement with contemporary bioprostheses between 1990 and 2006 (mean follow-up 4.5 +/- 3.1 years, maximum 17.3 years). Of these patients, 150 received LLT (including statins) early after surgery. Prosthetic valve haemodynamics on echocardiography and freedom from re-operation for SVD were compared between patients who did and did not receive postoperative LLT. Results: After bioprosthetic implantation, the progression of peak and mean trans-prosthetic gradients during echocardiographic follow-up (mean 3.3 years) was equivalent between patients treated with and without LLT (peak increase: 0.9 +/- 7.7 vs 1.1 +/- 10.9 mmHg, LLT vs no LLT, P = 0.87; mean increase: 0.8 +/- 4.1 vs 0.2 +/- 5.9 mmHg, LLT vs no LLT, P = 0.38). The annualised linear rate of gradient progression following valve replacement was also similar between groups (peak increase per year: 2.0 +/- 12.1 vs 1.0 +/- 12.9 mmHg per year, LLT vs no LLT, P = 0.52; mean increase per year: 0.5 +/- 2.2 vs 0.6 +/- 6.0 mmHg per year, LLT vs no LLT, P = 0.94). The incidence of mild or greater aortic insufficiency on the most recent echocardiogram was comparable (16.3% vs 13.8%, LLT vs no LLT, P = 0.44), and there was no difference in the 10-year freedom from re-operation for SVD between the two groups [98.9% (95% confidence interval (CI): 91.9%, 99.8%) vs 95.4% (95% CI 90.5%, 97.9%), LLT vs no LLT, P = 0.72]. Conclusions: In this observational study, there was no association demonstrated between early postoperative LLT and a slowing of bioprosthesis SVD. With the excellent durability of bioprostheses in the current era, a prospective randomised trial of statin therapy to prevent bioprosthetic SVD does not appear to be justified, let alone feasible. (C) 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.