Although current guidelines recommend 3 months of anticoagulation treatment after bioprosthetic aortic valve replacement surgery, a study that included more than 4,000 patients found that patients who had warfarin therapy continued between 3 and 6 months after surgery had a lower rate of cardiovascular death, according to a study in the November 28 issue of JAMA.
"Biological prostheses are preferred to mechanical valves for aortic valve replacement (AVR) surgery in elderly patients older than 65 years because of shorter life expectancy and lack of a need to use anticoagulation treatment in the long-term. Especially in these patients, the tradeoff between thromboembolic complications due to the valve implant and bleeding events as adverse effects from anticoagulation therapy must be balanced. Nevertheless, appropriate duration of anticoagulation treatment postoperatively is yet to be established because the risk of complications when the treatment is discontinued is unknown," according to background information in the article. The current recommendation of 3 months of warfarin treatment after bioprosthetic AVR surgery is primarily based on results from 1 retrospective study with a limited number of events.
Charlotte Merie, M.D., of the Copenhagen University Hospital Gentofte, Copenhagen, Denmark and colleagues investigated whether discontinuation of warfarin treatment within prespecified periods after bioprosthetic AVR surgery was associated with increased risk of thromboembolic complications, cardiovascular death, and bleeding incidents. Through a search in the Danish National Patient Registry, 4,075 patients were identified who had bioprosthetic AVR surgery performed between January 1997 and December 2009. The researchers determined the incidence rate ratios (IRRs) of strokes, thromboembolic events, cardiovascular deaths, and bleeding incidents by discontinuing warfarin as opposed to continued treatment at 30 to 89 days, 90 to 179 days, 180 to 364 days, 365 to 729 days, and at least 730 days after surgery. Average age of the patients was 75 years; 41 percent were women.
Overall, 361 patients (8.9 percent) experienced a stroke, 615 (15.1 percent) had a thromboembolic event, and 364 (8.9 percent) encountered a bleeding incident after the date of surgery. During the observation period, 1,156 patients (28.4 percent) died, with 879 (76.0 percent) of these deaths related to cardiovascular disease. The IRRs for patients not treated with warfarin compared with those treated with warfarin were 2.46 for stroke; 2.93 for thromboembolic events; 2.32 for bleeding incidents; and 7.61for cardiovascular deaths within 30 to 89 days after surgery; and 3.51 for cardiovascular deaths within 90 to 179 days after surgery.