How the Apple Watch Series 4 can track heart health

What’s the probability that a watch can correctly detect atrial fibrillation (AFib)? That’s to be determined, but Apple is betting on it with the new Apple Watch Series 4. The watch has received clearance from the Food and Drug Administration to be able to conduct electrocardiograms and deliver alerts if AFib is detected.

AFib is the most common sustained arrhythmia in adults worldwide; it is an irregular and often rapid heart rate that often causes poor blood flow. Its exact cause is unknown.

To obtain a reading, the user needs to press one finger against a button on the Apple watch. Thirty seconds later, the watch will deliver a heart rhythm classification indicating whether the heart’s rhythm is normal or irregular.

It sounds relatively easy, but there is a lot to consider when trusting such technologies. Roderick Tung, MD, associate professor of medicine and director of cardiac electrophysiology, shared his thoughts on the watch.

“I think it’s a total game-changer to be able to record an electrocardiogram from a wearable device. Currently the things that allow patients to monitor their heart rates only count their pulse rate,” said Tung. “But they don’t actually allow us to get tracing to help us come up with a diagnosis.”

As of now, in order to trigger a diagnosis, a patient must wear inconvenient monitors for one day to as long as thirty days. This is because a symptom-rhythm correlation, which is electrocardiographic evidence of the patient's cardiac rhythm obtained at the time of symptoms, is needed to achieve a proper diagnosis. The Apple Watch may solve this problem, but as Tung points out, the heart tracings need to be reliable. This sort of technology also opens the door to unwanted anxiety.

“Wearables are actually a double-edged sword. Because in general we always try to urge our patients who have arrhythmia and palpitations to relax and be less anxious,” said Tung. “And when you constantly think about your heart rate, your state of arousal is higher. That may actually increase adrenaline levels and potentially worsen arrhythmias.”

For someone who does not suffer from an arrhythmia or anxiety, wearables can encourage a lot of positive changes. They can inspire people to keep track of their sleep, count their calories and take more control of their health in general. However, wearables should never replace a visit to your physician.

“You can’t consult your Apple Watch and Google for a diagnosis,” said Tung. “If your watch indicates atrial fibrillation, then you should see a heart rhythm specialist or cardiologist.”