Heart rhythm monitoring with a smartwatch

These wrist-worn devices are better than ever at gathering data. But it's still too early to use them to screen for atrial fibrillation.

The original wristband monitors were pretty basic: they tracked your movement and tallied your daily steps. But before long, these digital devices could also estimate your heart rate, thanks to a sensor that measures changes in blood flow through your skin. Now, there are smartwatches with special sensors that can record a tracing of your heart's electrical signature (electrocardiogram or ECG) and alert you if it detects an irregular rhythm.

Last fall, the FDA granted Apple approval for the ECG sensor and an app that includes an algorithm to detect atrial fibrillation, or afib, the most common heart rhythm disorder (see "What is atrial fibrillation?"). While the Apple Watch Series 4 is the first of its kind to offer this feature, other companies have similar technologies in the works.