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Well-managed warfarin therapy associated with low risk of complications in patients with atrial fibrillation

The JAMA Network Journals

In a study published online by JAMA Cardiology, Fredrik Björck, M.D., of Umea University, Umea, Sweden and colleagues evaluated the efficacy and safety of well-managed warfarin therapy in patients with nonvalvular atrial fibrillation.

Atrial fibrillation (AF) is a strong independent risk factor for ischemic stroke. Vitamin K antagonist (eg, warfarin) treatment reduces the risk of stroke by 64 percent and all-cause mortality by 26 percent. However, warfarin confers an increased risk of hemorrhage, with intracranial bleeding the most severe effect. An alternative of warfarin for stroke prevention in AF are non-vitamin K antagonist oral anticoagulants. For this study, the researchers included data from Swedish registries and a total of 40,449 patients starting warfarin therapy owing to nonvalvular AF, who were monitored until treatment cessation, death, or the end of the study.

The researchers found that the annual incidence of all-cause mortality was 2.19 percent and, for intracranial bleeding, 0.44 percent. Patients also taking aspirin had annual rates of any major bleeding of 3.07 percent and thromboembolism (blood clot) of 4.9 percent, and those with renal failure were at higher risk of intracranial bleeding. "Therapy should be closely monitored in those with renal failure, concomitant aspirin use, and an individual time in therapeutic range (iTTR) less than 70 percent or a high international normalized ratio (INR) variability. The iTTR is a strong indicator of probability for both bleeding and thromboembolic events and should be maintained at 70 percent or greater."

"Well-managed warfarin treatment is a valid alternative in patients with AF who require anticoagulant treatments, with relatively low complication rates and low all-cause mortality," the authors write.


(JAMA Cardiology. Published online April 20, 2016; doi:10.1001/jamacardio.2016.0199. Available pre-embargo to the media at

Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Note: An accompanying editorial, "Using Data to Guide Anticoagulation in Patients With Atrial Fibrillation," by John H. Alexander, M.D., M.H.S., and Laine E. Thomas, Ph.D., of the Duke Clinical Research Institute, Durham, N.C., is available pre-embargo at the For The Media website.

Media Advisory: To contact Fredrik Björck, M.D., email

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