The ECG app packs a high-performance ECG sensor module, which provides single-lead ECG measurements, real-time analysis, and sinus rhythm, atrial fibrillation, and premature atrial and ventricular beat reminders*, to stay informed and proactive about major heart health-related risks. New and improved electrode technology has made ECG signal collection more accurate and responsive, with the addition of PVD-coated electrodes on the curved, transparent sapphire caseback, resulting in a comfortable, skin-tight fit. Just touch the electrode on the side for 30 seconds, real-time result can be shown on your watch after the measurement.