New tool offers a more precise way to assess stroke risk in people with atrial fibrillation

Researchers at the University of Vermont have developed a more precise way to assess stroke risk in people with atrial fibrillation (A-Fib), a condition that affects 10.5 million Americans and is a leading cause of stroke.

Their findings, published August 6 in the Journal of Thrombosis and Haemostasis, show that adding simple blood tests to an existing risk calculator can help physicians better determine who truly needs anticoagulant medications-powerful drugs that prevent strokes but can also cause dangerous bleeding. The researchers posted a new improved stroke risk calculator online for physicians' easy access.

This could be a game-changer for stroke prevention. We're giving physicians a sharper tool to provide a personalized approach to anticoagulation for patients who need it most, while sparing others from unnecessary risk."

Mary Cushman, M.D., M.Sc., principal investigator, University Distinguished Professor of Medicine and Pathology & Laboratory Medicine, Larner College of Medicine, University of Vermont

Anticoagulant medications can reduce stroke risk for some people with A-Fib, but some people who take anticoagulants experience a breakthrough stroke anyway, and the medications can cause dangerous side effects related to uncontrolled bleeding. To estimate a patient's stroke risk before prescribing anticoagulants, physicians can use a conventional risk calculator, called the CHA₂DS₂-VASc score, that considers a patient's age, sex, and medical history. The CHA₂DS₂-VASc score has limited capability, and it does not account for other important risk factors, including heart dysfunction, accelerated blood clotting, and inflammation, which can be assessed with blood tests.

The improved CHA₂DS₂-VASc-Biomarkers risk calculator accounts for those additional risks factors by adding the blood tests to the calculation. It is based on two studies led by researchers at the Vermont Center for Cardiovascular and Brain Health and the Department of Medicine at the university's Larner College of Medicine. This research was supported by funding from the U.S. National Institutes of Health/National Institute of Neurological Disorders and Stroke.

In the first study, the investigators looked at nine blood tests that might predict the occurrence of stroke in 713 people who were taking an anticoagulant to prevent stroke. With a 12-year follow up, 9 percent of these people developed a breakthrough stroke. The investigators found that three blood test results that identify proteins associated with heart dysfunction, accelerated clotting, and inflammation activity were related to the risk of a stroke.

In the second study, the investigators looked at the same 9 blood tests in 2,400 people who were not taking an anticoagulant to prevent stroke. Over 13 years, 7 percent of them developed a stroke. The investigators discovered that two of the blood tests increased the ability of the CHA₂DS₂-VASc score to predict a stroke. The researchers used these two blood tests to create a more accurate risk scoring system, called CHA₂DS₂-VASc-Biomarkers score. This improved scoring system can be used by clinicians to decide which patients with atrial fibrillation might benefit the most from anticoagulant medication.

"This will help doctors better select patients for anticoagulation, potentially saving lives and reducing health care costs," said lead author Samuel Short, M.D. '23. Now a hematology fellow at the University of North Carolina Chapel Hill, Short began this research as a medical student at the Larner College of Medicine, working with Cushman as faculty mentor. They used data from the an ongoing national study, Reasons for Geographic and Racial Differences in Stroke (REGARDS), a cohort study of 30,239 adults monitored for stroke and related diseases.

Short presented an early abstract of this research at the American Heart Association's Epidemiology and Prevention/Lifestyle and Cardiometabolic Health 2024 Scientific Sessions.

The new CHA₂DS₂-VASc-Biomarkers risk calculator will be available at www.uvm.edu/chadsvascb