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.
Monday September 15, 2025 12:00 am PDT by Eric Slivka
Update 10:06 a.m.: iOS 26 is rolling out now, though it may take a bit for all users to see it, so keep checking!
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As always, there is more to come. In his Power On newsletter today, Bloomberg's Mark Gurman said Apple plans to release many products in the...
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In the iOS 26 release notes, Apple is warning iPhone users that installing the new software might have a temporary impact on battery life, which is normal.
A new support document explains that major iOS updates require background setup like indexing data and files for search, downloading new assets, and updating apps.
Further, Apple says that new features could require more resources,...
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Apple today released updated firmware for the AirPods Pro 2 and the AirPods 4, introducing support for the new AirPods features that are included in iOS 26, iPadOS 26, and macOS Tahoe.
The firmware has a build number of 8A356, and it replaces the current 7E93 firmware.
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Friday September 12, 2025 7:58 am PDT by Tim Hardwick
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iPhone 17
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The iPhone...
Saturday September 13, 2025 10:01 am PDT by Joe Rossignol
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T-Mobile President Jon Freier today shared real-world photos of Apple's boxes for the iPhone Air, iPhone 17 Pro, and iPhone 17 models, which launch on Friday.
Image Credit: Jon Freier
Apple has typically included iPhone box renders in its product environmental reports, but it did not do so for the latest models. However, Apple's iPhone Upgrade Program page does offer some images of the boxes, ...
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*
