Apple's new ad showcases how the Apple Watch alerted an athlete named Connor to atrial fibrillation. Connor's fast heart rate during training prompted him to use the ECG app on his Apple Watch, which detected the condition. Doctors subsequently discovered Connor had a congenital heart condition, leading to life-saving open-heart surgery. The ECG app is available on Apple Watch Series 4 and newer, and all Apple Watch Ultra models, but not on SE models.