Apple has been granted De Novo classification by the FDA for the Apple Watch Series 4. This certification as a unique device allows Apple Watch customers running watchOS 5.1.2 access to features that enable the detection of irregular heart rhythms. Consumers will be notified when the PPG-enabled algorithm detects an irregular heartbeat. The electrical heart sensor, in conjunction with the companion ECG app, generates an ECG similar to a single-lead (Lead I) ECG to look for the presence of atrial fibrillation (AF) with a greater than 98% sensitivity and 99% specificity when compared to reference ECG devices. The device can distinguish between a normal heartbeat, or sinus rhythm, and atrial fibrillation. Other features of the Apple Watch Series 4 include access to Medical ID and fall detection. You'll notice fairly quickly that Apple asks if you're already been diagnosed with the condition. If you have, the irregular rhythm feature is not for you. Apple doesn't want its device to be the primary monitoring tool for people who have a medical condition that puts them at a higher risk of strokes and other potentially fatal outcomes. Instead, it wants to help people who don't know they have it take the first step to get a diagnosis: About a quarter of the 2.3 million people who have atrial fibrillation won't experience any symptoms. You'll then get a notification about everything that the Apple Watch does not do. It won't track heart attacks, help you get off meds or replace your doctor, among other things. Apple describes the device as an "intelligent guardian" for your health, but it clearly doesn't want users to make important medical decisions on their own.