Afib detection: Apple Watch beats your doctor, study finds
If you’ve got an Apple Watch, it might be reassuring to know that those heart-monitoring features actually work.
Published in JACC Journals, the EQUAL Study from Amsterdam UMC put the watch up against standard medical care for detecting atrial fibrillation—the irregular heartbeat that can cause strokes if left undiagnosed. Researchers followed 437 patients in the Netherlands, all over 65 and at elevated stroke risk, for six months.
Half wore Apple Watches for 12 hours a day. The other half got traditional monitoring via chest electrodes, which only record for a couple of weeks at a time, unlike the Apple Watch, which records multiple times an hour.
After six months, 21 people in the smartwatch group had their atrial fibrillation detected, compared to just 5 in the standard care group. Roughly 10% versus 2% – a statistically significant difference.
Atrial fibrillation comes and goes. Your heart might behave perfectly during a two-week monitoring window, then misfire a month later. A watch worn daily for months has more opportunities to catch it.
The study used both the watch’s manual ECG function and its PPG sensor, which measures your pulse via light on your skin. Other smartwatches have similar capabilities, so the findings likely extend beyond Apple. That said, companies tend to more readily implement manually taken ECG readings with wearables, these can only detect Afib events while they are happening. It is less common for wearable companies to detect anomalies using a continuous optical PPG sensor like Apple.
Take Out
It’s a modest sample size, but the core finding holds: continuous monitoring catches more cases, particularly the silent ones—and that could mean the difference between prevention and a stroke.
This article is part of the site’s sports science reference for endurance athletes.
Last Updated on 3 June 2026 by the5krunner
My favourite kit and nutrition
- Maurten — the race nutrition trusted by elite athletes. Gels and drink mix engineered to be easy on the stomach.
- Garmin 90-degree charging adapter — the small adapter that keeps your charging cable tidy at the stem. Essential for race day.
- Garmin charging puck — the fastest and most reliable way to top up your Garmin before a session.
- Ravemen FR300 — front light that mounts directly under your Garmin or Wahoo head unit. Keeps your bars clean and your beam pointed where it matters.
- Garmin Varia RTL515 — radar rear light that alerts you to vehicles approaching from behind. Pairs with your Edge or Garmin watch.
- Stryd — the footpod that brings running power to your Garmin. The single most useful running upgrade I have made.
- Favero Assioma Pro RS2 — the power meter pedals most serious cyclists end up choosing. Accurate, easy to move between bikes.
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tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors. ID
Fact note: The cited article was not/will not be published on ScienceDirect, but in the JACC, Journal of the American College of Cardiology. https://doi.org/10.1016/j.jacc.2025.11.032
ty (changed)
it was also variosuly cited as being published by Harvard, so I admit to being confused on this. I did link to the correct paper.
Another fact note: I am not a native English speaker, so I wanted to translate your response using deepl.com. Unfortunately, it is not possible to copy text using Ctrl+C here in the discussion window.
you cannot copy text from this site unless you are logged in as a subscriber.
you can translate easily with other means eg firefox has translation built in to the url bar