Stroke Risk Increases Over Time in Many Patients With A-fib

Estimated stroke risk commonly increases over time among patients with A-fib who do not initially meet the threshold for oral anticoagulation therapy, new data affirm, highlighting the need for periodic reassessments.

Among patients with initially low CHA2DS2-VASc scores, 16.1% of men and 16.2% of women had scores that would qualify them for anticoagulation a year later, lead author Tze-Fan Chao, MD (Taipei Veterans General Hospital and National Yang-Ming University, Taiwan), and colleagues report in a research letter published online last week ahead of print in Annals of Internal Medicine. Those proportions rose to roughly one-quarter at 2 years and nearly half at 7 years.

“The CHA2DS2-VASc scores should be reassessed at least annually in AF patients, so that oral anticoagulants could be provided in a timely manner to avoid ischemic stroke when patients are not low risk anymore,” one of the senior authors, Shih-Ann Chen, MD (Taipei Veterans General Hospital and National Yang-Ming University), told TCTMD in an email.

Guidelines for the management of A-fib—such as those from the American Heart Association, the American College of Cardiology, and the Heart Rhythm Society—recommend reassessing “the need for and choice of antithrombotic therapy at periodic intervals,” but the optimal length of that interval is not defined.

“More clear recommendations for the importance of stroke risk reassessment, including the suggested timing interval, should be considered to be incorporated into the future guidelines to inform clinical practice,” Chen said. His group is recommending 1 year, although he acknowledged that more frequent follow-up would probably identify patients with new risk factors sooner. “However, the compliance of patients for more frequent follow-up and the cost-benefit ratio should also be considered,” Chen added.

Risk ‘Not Static’

Commenting for TCTMD, Paul Friedman, MD (Mayo Clinic, Rochester, MN), said the study raises an important point about the need to reevaluate stroke risk in patients with atrial fibrillation.

“We all recognize it’s not static. That is, age is one of the variables [in the CHA2DS2-VASc score],” he said. “I don’t know if there’s the same extent of awareness of the fact that the other risk factors also evolve over time.”

Failing to reassess risk in a patient with an initially low score “could lead to the potential for undertreatment and having people be at a higher risk than we would think if it’s not being reassessed at reasonable intervals,” Friedman said, adding that he agrees with the authors that 1 year is an appropriate interval.

The CHA2DS2-VASc score—which incorporates age, sex, and history of congestive heart failure, hypertension, diabetes, vascular disease, and stroke/TIA/thromboembolism—is commonly used to assess stroke risk in patients with A-fib. In general, oral anticoagulation is recommended when the score is at least 1 in men and 2 in women.

Tracking CHA2DS2-VASc

To see how often patients with a low stroke risk calculated at baseline had increases in CHA2DS2-VASc score to then meet criteria for anticoagulation therapy, the investigators turned to the Taiwan National Health Insurance Research Database. They looked at data on 14,606 patients (mean age 48; 40% women) with newly diagnosed A-fib and a CHA2DS2-VASc score of 0 (for men) or 1 (for women) initially who did not receive antiplatelets or oral anticoagulants.

During a mean follow-up of 3.24 years, more than one-third of patients (36.3%) developed at least one new risk factor, giving them a CHA2DS2-VASc score that would make them eligible for anticoagulation therapy.

Chen pointed out that the appropriate interval for reassessing stroke risk in these types of patients has not been studied and thus varies widely in practice.

Michael Field, MD (Medical University of South Carolina, Charleston), who said that this study “nicely highlights how the CHA2DS2-VASc score is not static,” told TCTMD in an email that it is common to follow patients with A-fib on an annual basis.

“It is also recommended that treatment decisions regarding anticoagulation be reassessed at each visit, both to elicit clinical changes that might portend a higher stroke risk but also to assess changes in bleeding risk, drug interactions and compliance, and patient preferences,” Field said.

He added that each visit should also involve reassessments of other aspects of A-fib care, “including whether the patient has adequate rate control, whether a rhythm control drug or ablation is indicated, and assessing opportunities to treat risk factors such as sleep apnea, obesity, and high blood pressure.”