Association of warfarin therapy duration after bioprosthetic aortic valve replacement with risk of mortality, thromboembolic complications, and bleeding

Abstract

Context: The need for anticoagulation after surgical aortic valve replacement (AVR) with biological prostheses is not well examined.

Objective: To perform a nationwide study of the association of warfarin treatment with the risk of thromboembolic complications, bleeding incidents, and cardiovascular deaths after bioprosthetic AVR surgery.

Design, setting, and participants: Through a search in the Danish National Patient Registry, 4075 patients were identified who had bioprosthetic AVR surgery performed between January 1, 1997, and December 31, 2009. Concomitant comorbidity and medication were retrieved. Poisson regression models were used to determine risk.

Main outcome measures: Incidence rate ratios (IRRs) of strokes, thromboembolic events, cardiovascular deaths, and bleeding incidents by discontinuing warfarin as opposed to continued treatment 30 to 89 days, 90 to 179 days, 180 to 364 days, 365 to 729 days, and at least 730 days after surgery.

Results: The median duration of follow-up was 6.57 person-years. Estimated rates of events per 100 person-years in patients not treated with warfarin compared with those treated with warfarin with comparative absolute risk were 7.00 (95% CI, 4.07-12.06) vs 2.69 (95% CI, 1.49-4.87; adjusted IRR, 2.46; 95% CI, 1.09-5.55) for strokes; 13.07 (95% CI, 8.76-19.50) vs 3.97 (95% CI, 2.43-6.48; adjusted IRR, 2.93; 95% CI, 1.54-5.55) for thromboembolic events; 11.86 (95% CI, 7.81-18.01) vs 5.37 (95% CI, 3.54-8.16; adjusted IRR, 2.32; 95% CI, 1.28-4.22) for bleeding incidents; and 31.74 (95% CI, 24.69-40.79) vs 3.83 (95% CI, 2.35-6.25; adjusted IRR, 7.61; 95% CI, 4.37-13.26) for cardiovascular deaths within 30 to 89 days after surgery; and 6.50 (95% CI, 4.67-9.06) vs 2.08 (95% CI, 0.99-4.36; adjusted IRR, 3.51; 95% CI, 1.54-8.03) for cardiovascular deaths within 90 to 179 days after surgery.

Conclusion: Discontinuation of warfarin treatment within 6 months after bioprosthetic AVR surgery was associated with increased cardiovascular death.