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Association of Warfarin Therapy Duration After Bioprosthetic Aortic Valve Replacement With Risk of Mortality, Thromboembolic Complications, and Bleeding
Study Questions:
What are associations between warfarin treatment and the risk of thromboembolic complications, bleeding, and cardiovascular death after bioprosthetic aortic valve replacement (AVR)?
Methods:
This was a retrospective study of patients in the Danish National Patient Registry who had bioprosthetic AVR between 1997 and 2009. The main outcome measures were time-dependent incidence rate ratios of stroke, thromboembolic events, and bleeding by discontinuing warfarin versus continued anticoagulation postoperatively.
Results:
Estimated rates of events per 100 person-years in patients not treated with warfarin compared with those treated with warfarin with comparative absolute risks were 31.74 (95% confidence interval [CI], 24.69-40.79) versus 3.83 (95% CI, 2.35-6.25) for cardiovascular deaths within 30-89 days after surgery; and 6.50 (95% CI, 4.67-9.06) versus 2.08 (95% CI, 0.99-4.36) for cardiovascular deaths within 90-179 days after surgery. For every 23 (95% CI, 14-54) patients not being treated with warfarin, one patient died from cardiovascular cause. For every 74 (95% CI, 27-95) patients being treated with warfarin, one patient experienced bleeding requiring hospitalization.
Conclusions:
Warfarin in the initial 3-6 months after bioprosthetic AVR is associated with a reduced risk of cardiovascular death.
Perspective:
Current guidelines, which suggest 3 months of postoperative warfarin following bioprosthetic AVR, are based on limited data. The current study, although limited by a retrospective study design and the lack of some data (e.g., time in therapeutic range) in an administrative database, offers compelling evidence for warfarin in the initial 3 months after surgery, and even up to 6 months postoperatively. These data implicate a need to revisit the guidelines and, at a minimum, suggest broader adherence to short-term warfarin following a bioprosthetic AVR.
Keywords: Outcome Assessment, Health Care, Incidence, Heart Valve Prosthesis, Blood Coagulation, Bioprosthesis, Cardiology, Warfarin, Hemorrhage, Postoperative Period
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