Apple has started the roll-out of the latest version of its smartwatch software, Watch OS 5.1.2. This update activates the heart rate sensor to allow users of the latest Apple Watch in the US to conduct their own ECGs. For users elsewhere in the world, the new feature still needs certification by local regulatory authorities.
The Apple Watch sensor checks the heart rate in the background and notifies the user if it finds an irregular heart rhythm that appears to be atrial fibrillation. To take an ECG recording at any time or following an irregular rhythm notification, users launch the new ECG app on Apple Watch Series 4 and hold their finger on the Digital Crown to activate the electrodes built into the device. After 30 seconds, the heart rhythm is classified as either AFib, sinus rhythm or inconclusive. All recordings, their associated classifications and any noted symptoms are stored in the Health app on the user's iPhone and can be shared as a PDF with physicians.
Apple said it worked with the US Food and Drug Administration for a number of years to receive De Novo classification for the ECG app and the irregular heart rhythm notification, making the features available over the counter. The ECG app’s ability to accurately classify an ECG recording into AFib and sinus rhythm was validated in a clinical trial of around 600 participants. The study found the ECG app on Apple Watch demonstrated 98.3 percent sensitivity in classifying AFib and 99.6 percent specificity in classifying sinus rhythm in classifiable recordings. In the study, 87.8 percent of recordings could be classified by the ECG app.
