With the ECG app on Apple Watch Series 4 or later, you can take an ECG similar to a single-lead electrocardiogram. The ECG app can record your heartbeat and rhythm using the electrical heart sensor on Apple Watch Series 4 and then check for signs of atrial fibrillation (AFib), a form of irregular rhythm. Features • Allows you to take an ECG similar to a single-lead electrocardiogram • Take an ECG at any time, when you’re feeling symptoms such as a rapid or skipped heartbeat, or when you receive an irregular rhythm notification. • The ECG app can indicate whether your heart rhythm shows signs of atrial fibrillation—a serious form of irregular heart rhythm—or sinus rhythm, which means your heart is beating in a normal pattern. • Saves ECG waveform, classification and any noted symptoms in a PDF on the Health app on iPhone to share with your doctor.