Blood-Thinning Drugs and Stroke Risk: What a New AF Trial Found

The New England Journal of Medicine posted findings from the SINGLE-AF trial, noting that patients with atrial fibrillation (AF) — an irregular heartbeat that can cause blood clots to form in the heart — who sit in an intermediate risk category for stroke have until now occupied an awkward gap in treatment guidance. Current guidelines suggest that direct oral anticoagulants (DOACs), a type of blood-thinning medication taken by mouth, should be considered for this group. But the guidance has been based on expert opinion rather than hard evidence from randomised controlled trials.

The SINGLE-AF trial was designed to fill that gap. Its findings have been published by the NEJM and summarised in a short video format the journal calls a Quick Take.

AF affects around 1.4 million people in the UK, according to the NHS, and is one of the leading causes of stroke. The condition causes the upper chambers of the heart to beat chaotically, which can allow blood to pool and clot. If a clot travels to the brain, it causes a stroke.

Doctors assess individual stroke risk using a scoring tool called CHA₂DS₂-VASc, which awards points for age, sex, and conditions such as diabetes, high blood pressure, and previous stroke. Patients who score in the middle range — neither clearly low-risk nor clearly high-risk — are the group the SINGLE-AF trial targeted.

Anyone with AF who is unsure about their treatment or risk level should speak to their GP rather than adjusting medication themselves. NHS 111 is available around the clock for non-emergency health queries.

Key information

• Speak to your GP if you have AF and want to discuss stroke risk or blood-thinning medication
• Do not stop or start anticoagulant medication without medical advice
• Call NHS 111 for non-emergency health questions, 24 hours a day
• In an emergency, call 999