Apple has designed a new algorithm that Apple Watch uses to measure electrocardiogram (ECG) waves, according to developer documentation for the iOS 14.3 and watchOS 7.2 betas.
In the official documentation, a new "version 2 algorithm" declaration has been added. No other information is included.
The ECG feature includes irregular heart rhythm detection, which intermittently measures the user's heart rate in the background and sends a notification if it detects an anomaly it categorizes as atrial fibrillation, which can be a serious heart arrhythmia condition.
Based on beta code uncovered by MacRumors, it's likely that the new algorithm will allow the ECG app to check for atrial fibrillation (AFib) at higher heart rates - during exercise, for example.
iOS 14.3 will introduce support for Apple Fitness+, Apple's upcoming fitness service that will work with the Apple Watch, plus it brings a new Cardio Fitness feature that lets you know if your VO2Max levels are low. VO2Max is a useful measurement of overall fitness and heart health.
iOS 14.3 is set to be released on Monday, December 14, which is also the day that Apple Fitness+ is coming out.
Apple is now selling refurbished versions of the Apple Watch Series 11, Apple Watch Ultra 3, and Apple Watch SE 3 at discounted prices.
This is the first time the Series 11, Ultra 3, and SE 3 have been available through Apple's online refurbished store since the devices launched last September.
Refurbished pricing on the 46mm GPS Apple Watch Series 11 starts at $369, down from $429, while ...
Apple today confirmed that watchOS 27 will not support the Apple Watch Series 8, Apple Watch Ultra (first generation), or Apple Watch SE (second generation), effectively drawing a line at devices equipped with the S9 or S10 chip.
The only Apple Watch models compatible with watchOS 27 are the Apple Watch Series 9, Series 10, Series 11, Ultra 2, Ultra 3, and SE 3.
The cuts are the biggest...
Apple today confirmed that the Apple Watch Series 9 is compatible with watchOS 27, after the device was mistakenly omitted from the software's official compatibility page.
Apple updated its website immediately following its WWDC 2026 keynote, and the watchOS 27 page listed a shorter compatibility list than many users expected: the Apple Watch SE 3, Series 10, Series 11, Ultra 2, and Ultra 3. ...
Wait what? The ECG only works when your finger is on the Digital Crown. It can’t work in the background.
The background irregular heart rhythm detection does not use the ECG but it is grouped with the ECG features (which is technically inaccurate but they are related features, just different technologies). It's been around as long as the ECG: "Using the optical heart sensor in Apple Watch Series 1 or later, the irregular rhythm notification feature will occasionally check the user’s heart rhythm in the background for signs of an irregular heart rhythm that appears to be AFib and alerts the user with a notification if an irregular rhythm is detected on five rhythm checks over a minimum of 65 minutes." (https://www.apple.com/newsroom/2018/12/ecg-app-and-irregular-heart-rhythm-notification-available-today-on-apple-watch/)
Still waiting for ECG in Japan! Any news about it?
Since ECG received final medical approval in Japan this September, I guess maybe iOS 14.3 will cover ECG functionality also Japan as well? *finger-crossed*
Apple's first foldable iPhone, with a book-style design featuring a ~5.5-inch outer display and a ~7.8-inch inner display with a minimal crease down the middle.
