Vitamin K antagonists and structural valve deterioration in bioprosthetic aortic valves.

Background: To evaluate the effect of postoperative vitamin K antagonist (VKA) exposure on structural valve deterioration (SVD) after bioprosthetic aortic valve replacement (AVR). Methods: We retrospectively analysed 123 patients who underwent surgical bioprosthetic AVR between 2010 and 2025 with adequate echocardiographic follow-up. VKA exposure was recorded during follow-up; for the primary time-fixed Cox model, VKA exposure was defined as cumulative postoperative use ≥3 months (yes/no), and VKA was additionally evaluated as a time-varying covariate in a time-dependent sensitivity analysis. The primary endpoint was VARC-3-defined SVD; secondary endpoints were all-cause mortality, bioprosthetic valve failure, and reoperation/valve-in-valve. Results: Mean age was 71.3±6.1 years; 65% were male. Porcine and bovine bioprostheses accounted for 71.5% and 28.5% of implants. Median SVD-free survival was 2073 days (95% confidence interval [CI]: 0-4212) in VKA users, while the median was not reached in non-users; the difference was significant (logrank p=0.017). In the adjusted time-fixed Cox model, VKA exposure was associated with higher SVD risk (adjusted hazard ratio [aHR] 2.14; 95% CI 1.08-4.26; p=0.030). In a time-dependent sensitivity Cox model with VKA as a time-varying covariate, periods on VKA were similarly associated with higher SVD hazard (hazard ratio 2.16; 95% CI 1.10-4.23; p=0.025). Porcine bioprostheses were also independently associated with higher SVD risk (aHR 2.71; 95% CI 1.09-6.76; p=0.031). Conclusion: After bioprosthetic AVR, VKA exposure and porcine bioprostheses were independently associated with SVD. Antithrombotic strategies should consider the potential long-term adverse effects of VKA in the context of prosthesis material and patient characteristics. Prospective multicenter studies are needed to confirm these findings.