Atrial Fibrillation: Should You Take Medication Even If Your Risk Is Low? [Health Check]

[Financial News] A randomized clinical trial by Korean researchers has confirmed that anticoagulants can prevent complications in patients with atrial fibrillation at intermediate risk, a group for which evidence guiding treatment decisions has been lacking.
A research team from the Division of Cardiology at Severance Cardiovascular Hospital, comprising Professors Jung Bo-young, Yu Hee-tae and Kim Dae-hoon, announced on the 2nd that even patients with atrial fibrillation at intermediate risk of stroke should receive blood-thinning treatment with anticoagulants to reduce the incidence of complications such as stroke and systemic embolism.
Atrial fibrillation is an arrhythmia in which the heart beats irregularly. Blood can clot inside the heart, forming thrombi. If a thrombus travels through the blood vessels and blocks a cerebral blood vessel, it can cause a stroke. Anticoagulants, which inhibit blood clotting, are used to prevent this.
Patients with atrial fibrillation are classified according to their CHA2DS2-VA score, including groups at high and intermediate risk of stroke. Under current clinical guidelines, patients aged 75 or older who have a history of stroke, systemic embolism or similar events are classified as having high-risk atrial fibrillation, and anticoagulant therapy is strongly recommended.
By contrast, patients with only one stroke risk factor—such as hypertension, diabetes, heart failure, vascular disease or advanced age—are classified as being at intermediate risk, for whom anticoagulant therapy is presented as something that “may be considered.” This is because few clinical trials have directly compared treatment outcomes according to whether anticoagulants are used in intermediate-risk patients.
Professor Jung Bo-young’s research team conducted a clinical trial to evaluate the efficacy and safety of anticoagulants in patients with atrial fibrillation at intermediate risk. The team recruited 1,803 such patients from 18 medical institutions across South Korea, including Severance Cardiovascular Hospital, and randomly assigned them to two groups. A total of 902 patients in Group A took anticoagulants, while 901 patients in Group B did not receive them.
Over 24 months, the researchers monitored the occurrence of stroke; systemic embolism, in which a thrombus originating in the heart or elsewhere blocks another blood vessel; major bleeding occurring in the brain or other organs or requiring a transfusion; and cardiovascular death caused by the heart or other cardiovascular conditions.
These events occurred in four patients in Group A and 13 patients in Group B. The 24-month cumulative incidence showed that the risk in Group A was 69% lower than in Group B. In particular, ischemic stroke or systemic embolism occurred in one patient in Group A and 10 patients in Group B, indicating a 90% lower risk in Group A. The cumulative incidence of major bleeding, a concern associated with anticoagulant therapy, was similar in the two groups, and no cardiovascular deaths occurred in either group.
The significance of this study is that it used a randomized clinical trial to confirm that anticoagulants can prevent complications such as stroke and thromboembolism in patients with atrial fibrillation at intermediate risk, without clearly increasing the risk of major bleeding. Until now, there had not been sufficient evidence to guide treatment decisions for this group.
Professor Jung Bo-young said, “The study found that anticoagulant therapy can help reduce major clinical events, including stroke, even in patients with atrial fibrillation who have only one stroke risk factor.” She added, “We expect this study to serve as important evidence when deciding whether to provide anticoagulant therapy to intermediate-risk patients.”
The study was conducted with support from the Ministry of Health and Welfare (MOHW) and the National Evidence-based Healthcare Collaborating Agency, which oversees the Patient-Centered Clinical Research Coordinating Project, among other programs. The findings were published in the latest issue of The New England Journal of Medicine (NEJM, IF=84.5) and presented on the 28th of last month at the 2026 annual scientific meeting of the European Society of Cardiology and the World Heart Federation in Munich.



[email protected] Medical Reporter Jung Myung-jin Reporter