John Nosta, Fortune:

A 2019 study published in the New England Journal of Medicine (NEJM) examined this detection by smartwatches of “irregular pulses” in almost 420,000 people over eight months. In this study, which was funded by Apple, the authors concluded that the Apple Watch was effective in detecting AFib, stating that 84% of the smartwatch notifications were accurate in alerting for atrial fibrillation.

And:

But what the study didn’t find—or perhaps more accurately, didn’t even examine—is that the Apple Watch will largely not detect or categorize AFib at a heart rate greater than 120 beats per minute, according to information supplied to the FDA by Apple for the feature’s approval.

And:

In 2015, a study published in the Annals of Medicine found that in a cohort of 2,821 patients with new-onset AFib, the mean heart rate was 109 bpm. But, according to the study, roughly one-third of patients had a heart rate of over 120.

The point being made here is that Apple Watch will miss a significant number of AFib cases.

While this is true (assuming the studies are correct), consider the alternative. Without an Apple Watch, odds on catching AFib drop considerably.

The headline is a bit of a troll, though the article is interesting.

How about, “Apple Watch does a lot for your health, you should get one, but be aware Apple Watch will not detect AFib when your heart beats more than 200 times a sec. Mmmkay?”