Catheter Ablation May Eliminate Need for Blood Thinners in AFib Patients, Study Finds

A minimally invasive heart procedure called catheter ablation may reduce stroke risk enough that some atrial fibrillation patients can discontinue blood thinners, according to research presented at the American Heart Association's Scientific Sessions 2025. The international OCEAN Randomized Trial followed nearly 1,300 adults for three years after they underwent ablation to treat atrial fibrillation, a condition that increases stroke risk five-fold according to the American Heart Association's 2025 Heart Disease and Stroke Statistics report.

Researchers evaluated whether long-term oral anticoagulation remains necessary after successful ablation in people with moderate to high stroke risk. Participants included individuals with no evidence of irregular heart rhythm recurrence and those typically requiring long-term blood thinners. The study assigned half of eligible participants to take 75-160 mg of aspirin daily while the other half received 15 mg daily of rivaroxaban, a potent blood thinner.

The findings revealed that prescribing the blood thinner rivaroxaban after catheter ablation offered no significant advantage in stroke protection compared to aspirin while increasing bleeding risk. The three-year risk of stroke, including covert strokes detectable only through brain imaging, was 0.8% in the rivaroxaban group versus 1.4% in the aspirin group. Annual stroke risk measured 0.3% for rivaroxaban and 0.7% for aspirin, differences not statistically significant enough to indicate notable protection benefits from the stronger medication.

While no notable differences emerged in major or fatal bleeding complications between the two groups, clinically relevant non-major bleeding requiring medical attention occurred in 5.5% of rivaroxaban users compared to 1.6% of aspirin users, making such bleeding about 3.5 times more likely with the potent blood thinner. Study author Atul Verma, M.D., director of cardiology at McGill University Health Centre in Montreal, explained that catheter ablation for AFib not only reduces arrhythmia recurrence but also appears to reduce stroke risk associated with the condition.

The trial enrolled participants from healthcare centers in Canada, Australia, Germany, Belgium, Israel and China between March 2016 and July 2022. Researchers used the CHA2DS2-VASc score to measure stroke risk, with participants averaging a score of 2.2 and nearly 32% scoring 3 or higher, considered high risk. All participants underwent brain magnetic resonance imaging at enrollment and again after three years. Current American Heart Association/American College of Cardiology guidelines recommend continuing blood-thinning medications in moderate-to-high risk individuals even after successful ablation, but these findings suggest this approach may need reconsideration for certain patient populations.

Verma noted that many patients who undergo successful ablation ask whether they can stop blood thinners, and until now, physicians have advised continuation due to insufficient evidence supporting discontinuation safety. The study's findings provide evidence that successful ablation may allow safe discontinuation of potent blood thinners even for patients with moderate stroke risk. The research is simultaneously published as a full manuscript in the New England Journal of Medicine, though the study acknowledges limitations including relatively few participants with very high CHA2DS2-VASc scores of 4 or above, meaning findings may not apply to highest-risk individuals.