Aside from being able to detect irregular heartbeats, the Apple Watch might be able to monitor your blood oxygen levels, too. Tipsters talking to 9to5Mac discovered this feature by looking at iOS 14 code snippets. The wearable could let you know if your blood's oxygen saturation falls below the threshold.
Blood oxygen levels between 95% and 100% are considered healthy. If you hit below 80%, you might suffer from compromised heart and brain functionality. There's a risk of respiratory or cardiac arrest after continued low blood oxygen saturation.
It isn't clear what new hardware or software updates will be needed to make it happen. Engadget speculates it could copy Fitbit's approach of using red and infrared sensors to detect oxygen variation.
Apple is also looking to improve its ECG function so that it can deliver proper results for heart rates between 100 and 120 beats per minute, which is an issue with Apple Watch Series 4 and 5.