November 27th, 2012
Longer Warfarin Therapy After Bioprosthetic Aortic Valve Replacement May Be Beneficial
Three months of warfarin is the usual standard of care following bioprosthetic aortic valve replacement (AVR), although the supporting evidence base for this practice is limited. A new, large registry study published in JAMA suggests that more-prolonged warfarin therapy may be beneficial.
Danish researchers identified 4075 patients who underwent bioprosthetic AVR. As expected, warfarin treatment between 30 and 90 days after AVR was associated with significant reductions in stroke, thromboembolic events, and cardiovascular deaths (compared with no warfarin treatment). The benefits continued between 3 and 6 months, though the reduction in stroke became statistically nonsignificant. The authors calculated that for every 23 patients not being treated with warfarin between 3 and 6 months, one additional cardiovascular death occurred, at a cost of 1 bleeding complication requiring hospitalization for every 74 patients.
“With no randomized trials to guide the length of warfarin treatment, our results call for a review of guidelines in the field to consider an extension of the treatment to 6 months after surgery, especially in patients with an increased risk of cardiovascular death,” the authors wrote.
In an accompanying editorial, Shamir Mehta and Jeffrey Weitz write that, despite the limitations of an observational study, the results support a change in clinical practice in favor of prolonged warfarin therapy for as long as 6 months. They observe that the trial does not provide information about the possible role for the newer oral anticoagulants or about the role of adjunctive aspirin.