Atrial Fibrillation and Stroke Risk: What You Need to Know

Atrial Fibrillation and Stroke: What Singaporeans Need to Know

In Singapore, atrial fibrillation (AF) has become an increasingly important health issue, particularly as the population ages. According to local data, about 1.5% of people over 55 are affected, and in those over 80, the prevalence approaches 10%. AF is not just an irregular heartbeat—it raises the risk of stroke by about fivefold. In fact, 13–17% of ischemic strokes in Singapore are cardioembolic in nature, many of which are linked to AF. These figures highlight a critical truth: AF is not simply a cardiac condition; it is a major driver of stroke risk.

Many of my patients are aware of the danger of stroke, but in practice, their greatest fear is often not stroke itself—it is the possibility of severe bleeding from long-term medication. Warfarin, the traditional anticoagulant, has been in use for more than 60 years. Yet, it comes with significant limitations: strict dietary restrictions, frequent drug interactions, and the need for regular INR monitoring. Moreover, in Asian patients, including those in Singapore, the risk of bleeding on warfarin tends to be higher. Studies have shown that the percentage of time patients stay within the therapeutic INR range is suboptimal—about 58% for Chinese, 55% for Malays, and less than 50% for Indians. This instability increases both stroke and bleeding risks.

This is why, over the past decade, newer oral anticoagulants (NOACs) have become the standard of care. These medications—such as Pradaxa, Xarelto, Lixiana, and Eliquis—are much easier to use, requiring only once- or twice-daily dosing, without the need for blood tests. They are associated with lower rates of bleeding, especially intracranial hemorrhage, and studies confirm that they are both safer and more effective in Asian populations. In Singapore today, NOACs are widely used and recommended as first-line therapy.

Still, one question I hear frequently from patients is: “If I’ve had ablation and my heart rhythm is back to normal, why do I still need anticoagulants?” Traditionally, the consensus has been that if a patient has a high CHA₂DS₂-VASc score, anticoagulation should continue even after ablation.

However, the 2025 ALONE-AF trial has given us fresh insight. This study followed 840 patients who had undergone their first ablation and remained arrhythmia-free for at least a year. They were divided into two groups: one discontinued anticoagulation, and the other continued on NOACs. The results were striking—those who stopped had virtually no major bleeding, while stroke and systemic embolism rates were not significantly different between the groups. Overall, the composite outcome actually favored discontinuation.

From my perspective as a clinician, these findings suggest that for patients who remain arrhythmia-free for a year post-ablation, stopping anticoagulation can be a reasonable option. For those at high bleeding risk, it may even offer additional benefit. Yet, this does not apply to everyone. Patients at high stroke risk—those with a CHA₂DS₂-VASc score above 3 or a prior history of stroke—should continue anticoagulation, as current evidence is insufficient to support stopping in such cases.

It is also important to acknowledge the limitations of ALONE-AF. The study used only two Holter monitoring sessions of 24 to 72 hours to detect recurrences, which has a sensitivity of less than 25%. This means that many silent, asymptomatic recurrences could have been missed. In other words, while the results are encouraging, they are not conclusive enough to change practice for all patients.

Therefore, I interpret ALONE-AF as a signal of possibility rather than a universal rule. For low- to intermediate-risk patients, who have remained arrhythmia-free for a year and who also carry a high bleeding risk, stopping anticoagulation may be discussed as an option. But such decisions must be carefully individualized, risk-stratified, and grounded in thorough discussion between doctor and patient.

For those who truly cannot tolerate anticoagulation—because of bleeding or unstable INR—there is another alternative: left atrial appendage closure (LAAC). This minimally invasive procedure seals off the left atrial appendage, the site where most clots in AF originate. The procedure requires only a small puncture, heals quickly, and typically involves short-term antiplatelet therapy afterward. In Singapore, LAAC is increasingly available, but it is generally reserved for patients who cannot take anticoagulants, rather than as first-line therapy.

In summary, AF significantly raises stroke risk, and anticoagulation remains the foundation of prevention. NOACs have replaced warfarin as the mainstay of therapy in Singapore. Ablation can improve rhythm control, but it does not automatically mean medication can be stopped. ALONE-AF shows us that discontinuation may be safe under strict conditions, though its monitoring limitations remind us to proceed cautiously. For patients who cannot take anticoagulants at all, LAAC provides another pathway.

👉 My advice is simple: if you have AF in Singapore, never stop your anticoagulants on your own. Discuss your risks and goals with your specialist so that we can design the safest and most appropriate treatment plan for you.