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.
Thursday June 11, 2026 3:56 am PDT by Tim Hardwick
Remember Walkie-Talkie? Apple is apparently betting you won't.
The push-to-talk app has vanished from the first developer beta of watchOS 27, disappearing from both the app list and Control Center, with no way to bring it back. Apple hasn't said why, but it's probably because not many people used it.
If you include yourself in that cohort, here's a quick explainer.
Walkie-Talkie...
Apple's software updates previewed during WWDC 2026 this week have followed a distinct pattern: introduce a handful of key new features, while maintaining a focus on refining the underlying platform architecture. watchOS 27 is no different in this respect, with the majority of changes being performance improvements under the hood.
That said, one of the most obvious user-facing changes is a...
Apple's employees who participated in the company's annual Close Your Rings Challenge have begun to receive a limited-edition Apple Watch band and a special enamel pin marking the 10th anniversary of the internal challenge.
This year's band is a black Sport Loop with special lugs and an end piece that are colored similarly to the Apple Watch's Move, Exercise, and Stand rings.
Given that ...
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.
