Anticoagulation early after bioprosthetic sAVR lowers mortality risk

March 26, 2024

Patients are increasingly choosing biological aortic valve prostheses. Yet research about anticoagulation early after bioprosthetic surgical aortic valve replacement (sAVR) is conflicting.

Cardiovascular Surgery researchers at Mayo Clinic sought to compare all-cause mortality and thromboembolic events in patients receiving anticoagulation with warfarin and those not receiving anticoagulation following bioprosthetic sAVR. The retrospective study published in Mayo Clinic Proceedings in 2023 found that anticoagulation early after bioprosthetic sAVR lowers mortality risk.

"Warfarin use after bioprosthetic sAVR was associated with lower all-cause mortality and decreased risk of thromboembolism compared with not receiving warfarin. But there was an increased risk of major bleeding events," says Kevin L. Greason, M.D., a cardiovascular surgeon at Mayo Clinic in Rochester, Minnesota, and one of the study's authors. "The study findings support early warfarin use after sAVR in appropriately selected patients with a low risk of bleeding."

Because there is controversy about potential benefits and optimal duration of anticoagulation, guidelines are not always followed. As more patients opt for bioprosthetic sAVR, they may not be getting optimal treatment after valve replacement.

"The American Heart Association and the American College of Cardiology (AHA/ACC) and European guidelines advise consideration of a vitamin K antagonist for at least three months and for as long as six months after bioprosthetic sAVR in patients at low risk of bleeding. Despite this recommendation, only 28% of the patients in this administrative database received such anticoagulation," says Dr. Greason.

Previous U.S. studies addressing anticoagulation after bioprosthetic sAVR report data on anticoagulation at the time of hospital dismissal, and the prevalence rates vary from 16% to 54%, without information on the duration of treatment.

The Mayo Clinic researchers analyzed deidentified patient data from Jan. 1, 2007, to Dec. 31, 2019. The nationwide study included more than 10,000 patients of all ages and races throughout the U.S. The patients in the study had at least six months of continuous health insurance coverage before sAVR, a time period used to obtain their medical history.

The study found that patients who received warfarin had a lower risk of mortality (hazard ratio 0.68; P = 0.047). The cumulative incidence of thromboembolic events also was lower (hazard ratio 0.62; P = 0.09). However, the cumulative incidence of major bleeding events was higher for the warfarin group (subdistribution hazard ratio = 1.94; P = 0.002).

Anticoagulant treatment is often not prescribed early after surgery due to concerns about bleeding, but the study shows a significant reduction in two-year mortality and a trend toward reduced thromboembolism in the patients who received warfarin prescriptions early. Despite the possibility of bleeding, starting warfarin early is beneficial. "The increased risk of bleeding is a trade-off against the lower risk of all-cause mortality and thromboembolism," says Dr. Greason.

For more information

Huang Y, et al. Benefit of anticoagulation early after surgical aortic valve replacement using bioprosthetic valves. Mayo Clinic Proceedings. 2023;98:1797.

Refer a patient to Mayo Clinic.