Catheter ablation—a minimally invasive procedure to correct irregular heart rhythms—may reduce the risk of stroke to such an extent that some patients can discontinue blood thinners, according to preliminary late-breaking science presented at the 2025 American Heart Association (AHA) Scientific Sessions (7–10 November, New Orleans, USA).
In the OCEAN randomised trial, researchers evaluated whether long-term oral anticoagulation is needed after successful ablation in people with an increased risk of stroke. An international group of researchers enrolled nearly 1,300 adults at healthcare centres across Australia, Belgium, Canada, China, Germany and Israel between March 2016 and July 2022, and followed their progress for three years after they had ablation to treat atrial fibrillation (AF). Participants included people with no evidence of irregular heart rhythm recurrence and those with moderate-to-high stroke risk, which calls for long-term blood thinners.
Current AHA/American College of Cardiology (ACC) guidelines recommend continuing blood-thinning medications in moderate- to high-risk individuals to prevent stroke—even after a successful ablation.
“We know that ablation for AF is effective; however, we did not know if elimination of the arrhythmia also reduces the long-term risk of stroke,” said study author Atul Verma (McGill University Health Centre, Montreal, Canada). “Many people who have undergone successful ablation will ask, ‘can I stop my blood thinners?’ Until now, we have told them to continue taking blood thinners because we had insufficient evidence to suggest it was safe to stop. So, it was important to find out if successful ablation could allow discontinuing blood thinners.”
Researchers prescribed half of the eligible participants 75–160mg of daily aspirin, a mild antiplatelet, while the other half were prescribed 15mg of daily oral rivaroxaban, a potent blood thinner.
The study found that prescribing the blood thinner rivaroxaban after catheter ablation to treat AF offered no major difference in stroke protection versus taking aspirin, and increased bleeding risk compared to aspirin. More specifically, the three-year risk of stroke—including a covert stroke, which is only detectable on brain imaging—was 0.8% in the rivaroxaban group and 1.4% in the aspirin group. In addition, the annual stroke risk was 0.3% in the rivaroxaban arm and 0.7% in the aspirin arm—variances determined to be not significant enough to indicate a notable difference between groups.
There were also no notable differences in major or fatal bleeding complications whether people took rivaroxaban or aspirin. However, clinically relevant, non-major bleeding—bleeding serious enough to cause people to seek medical attention—was 5.5% for rivaroxaban versus 1.6% for aspirin, meaning it was roughly 3.5 times more likely with rivaroxaban.
“In essence, catheter ablation for AF reduced the recurrence of AF and can also reduce the risk of stroke associated with this common heart rhythm condition,” Verma noted. “With the notably increased bleeding risk associated with rivaroxaban, we concluded that the anticoagulant did not offer any advantages in comparison to aspirin for reducing what we found to be a low stroke risk in these individuals. Now, we can advise patients that it may be safe to stop blood thinners, even if they have a moderate stroke risk.”
The researchers believe that among the study’s limitations is the fact that only a small percentage of participants had a CHA2DS2-VASc score of 4 or higher. As a result, the findings may not be relevant to higher-risk individuals.
