European Heart Journal:

An 80-year-old lady with a work history as engineer presented with typical angina symptoms Canadian Cardiovascular Society Class III in our chest pain unit (CPU).

And:

The initial 12-channel ECG revealed no evidence for ischaemia. High-sensitive troponin I was also negative. The patient also complained about previous frequent episodes of ectopic beats which were recorded with her Apple watch. Further, Apple watch recordings included tracings with marked ST-segment depression.

And:

Based on this evidence of ischaemia, further diagnostic in the CPU was omitted and the patient was transferred to the catheterization laboratory, where a left main stem stenosis and a left anterior descending/diagonal bifurcation lesion. Accordingly, the patient was treated with coronary artery stenting and left the hospital a day later.

In a nutshell, the Apple Watch picked up a pattern because it had much more access to the patient’s heart data than a single visit to even the best hospital could capture.

This is still early days for Apple Watch and heartbeat irregularity detection. New heartbeat patterns that indicate a specific underlying condition are still being discovered. Some are known, but impossible to detect without constant heart monitoring. Apple Watch, and the underlying ECG pattern matching software are an incredibly valuable resource, one that continues to evolve. There’s way more here than AFib detection.