https://finance.yahoo.com/news/apple-unveils-watch-larger-display-fda-approved-ekg-reader-173936970.html

In addition, Apple also beefed up the Apple Watch’s ability to detect motion and heartbeat, including whether a user falls. The watch can also detect lower heart rates, as well as catch most cases of irregular rapid heartbeats, or “atrial fibrillation.” But perhaps most notably, the Apple Watch now lets users perform an electrocardiogram, or EKG, making the Apple Watch Series 4 the first FDA-approved, over-the-counter EKG consumer device. Performing EKGs can help users detect heart disease. Williams said the EKG features will roll out later this year.

Preorders for Apple Watch Series 4 begin on Friday, with units expected to ship on September 21. Prices start at $399 for the non-cellular aluminum models in space gray, silver and gold, and $499 for the non-cellular stainless steel models in silver, “polished graphite” and gold. Meanwhile, the Apple Watch Series 3 will remain available for sale at $379.