If you have atrial fibrillation, also called AFib, your doctor has probably run a quick scoring system to decide whether you need a blood thinner. Score high, and the answer is yes. Score low, and it’s no.
But land in the middle, and you may have been told it’s a judgment call. Maybe you walked out without a prescription.
A recent clinical trial says that call should lean toward treatment.
That matters because AFib, an irregular heartbeat, raises the risk of stroke about fivefold and causes about 1 in 7 strokes, according to the Centers for Disease Control and Prevention. The agency expects 12.1 million Americans to have it by 2050.
What the trial found
The SINGLE-AF trial was presented in late August at the European Society of Cardiology’s annual congress and published in the New England Journal of Medicine.
Researchers at 18 hospitals in South Korea enrolled 1,803 AFib patients at intermediate risk of stroke. Half got a modern blood thinner — apixaban (Eliquis) or rivaroxaban (Xarelto). The other half got none.
After two years, the combined rate of stroke, blood clots, major bleeding and cardiovascular death was 0.5% in the blood-thinner group vs. 1.5% in the untreated group. That’s a 69% reduction.
Most of the benefit came from preventing strokes: three ischemic strokes in the treated group versus 10 in the untreated group, according to the American College of Cardiology.
And the thing everyone worries about with blood thinners, bleeding, didn’t rise. Major bleeding was 0.3% vs. 0.5%.
The trial shows “patients with AF at intermediate stroke risk benefit from DOAC therapy,” said the study’s principal investigator, Dr. Boyoung Joung of Yonsei University in Seoul. DOAC is short for direct oral anticoagulant, the newer class of blood thinners.
Are you in the gray zone?
Doctors use a checklist called the CHA2DS2-VASc score. Under the 2023 U.S. guideline, you get:
- 1 point each for heart failure, high blood pressure, diabetes, vascular disease, being age 65 to 74, and being female
- 2 points each for being 75 or older, and having had a prior stroke, mini-stroke or blood clot
The trial’s intermediate group was men with a score of 1 and women with a score of 2.
Here’s how easy it is to land there. A healthy 66-year-old man with AFib scores a 1, just for his age. A healthy 66-year-old woman scores a 2. So a lot of people in their late 60s are sitting right in the gray zone.
Why this was a judgment call
U.S. guidelines already say a blood thinner is reasonable for this group, according to the American College of Cardiology (ACC). European guidelines are softer, saying it should be considered.
Why the hedging? Earlier evidence came mostly from observational studies, and Joung noted it was conflicting. SINGLE-AF is randomized, which is the kind of proof doctors trust most.
The fine print
Don’t read 69% and think this is a miracle drug. The absolute difference was about 1 percentage point over two years.
Put another way, treating 100 people like these for two years prevented roughly one serious event. That’s meaningful if you’re the one, but it’s not a slam dunk.
The trial was also small, with fewer events than researchers expected, and the ACC said the results should be read with caution. Patients knew which group they were in, averaged about 60 years old and were all Korean.
And blood thinners carry real risk. Bleeding, including serious and fatal bleeding, is the most important side effect, according to the FDA.
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What these drugs cost
Eliquis and Xarelto aren’t cheap. In 2023, a 30-day supply listed at $521 for Eliquis and $517 for Xarelto, according to the Centers for Medicare & Medicaid Services.
The good news for people on Medicare: both were among the first drugs with negotiated prices. Starting Jan. 1, 2026, Medicare’s price dropped to $231 for Eliquis and $197 for Xarelto. Here’s the list of drugs that got cheaper for millions of people on Medicare in 2026.
Don’t expect a cheap generic Eliquis soon. The earliest a generic can launch in the U.S. is April 1, 2028, according to Bristol Myers Squibb, which makes it with Pfizer.
If you’re not on Medicare or your copay is steep, it pays to shop around. You can compare prescription savings options here.
4 questions to ask your doctor
If you have AFib and aren’t on a blood thinner, take these to your next appointment.
1. What’s my CHA2DS2-VASc score?
Ask for the number, not just the verdict. If you’re a man at 1 or a woman at 2, you’re in the group this trial studied.
2. What’s my bleeding risk?
Your doctor should weigh your stroke risk against your bleeding risk. Ask what in your health history raises it, and whether any of your other medications add to it.
3. Does this trial change your advice for me?
It’s a fair question, and a good doctor will welcome it. There’s also a separate, observational study from Sweden that linked the newer blood thinners to slightly slower mental decline in people with AFib and Alzheimer’s, according to ScienceDaily. It’s another piece of the puzzle.
4. What will it cost me?
Check your plan’s coverage and copay before you fill the prescription. If you’re on Medicare, open enrollment runs Oct. 15 through Dec. 7, so that’s a good time to make sure your drug plan covers the blood thinner you’d take.
The bottom line
Don’t start or stop a blood thinner on your own. But if you have AFib and were told you’re borderline, this trial is a good reason to have the conversation again.
For more on protecting your heart, read about 10 of the worst possible foods for your heart health.
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