Name: How reliable are ECG functions in smartwatches?
Uploaded: 2025-11-24T11:51:01.840Z
Duration: 4 min 14 s
Description: Smartwatches record heart rate and ECGs — but how accurate are they? Two users test wearables against a medical electrocardiogram to see if watches can detect arrhythmias and support heart health. A cardiologist explains the limits.

Smartwatches record heart rate and ECGs — but how accurate are they? Two users test wearables against a medical electrocardiogram to see if watches can detect arrhythmias and support heart health. A cardiologist explains the limits.

A recent test compared the ECG functions of popular smartwatches with professional 12-lead ECG equipment at a cardiology clinic in Cologne. The results showed that the heart rate and rhythm readings from the smartwatches matched those from the clinical devices, with both providing accurate and comparable data for healthy users.

However, cardiologists caution that while smartwatch ECGs can be useful for monitoring occasional rhythm problems, they cannot detect heart attacks or replace a full medical examination. Users experiencing heart symptoms are advised to consult a doctor, as not all wearable devices are equally reliable.

How reliable are ECG functions in smartwatches?

Florian Henning and Leo Tetzlaff are ambitious runners. They race regularly. Fitness trackers are a part of their day-to-day lives. When I started running, I bought a smartwatch to track my progress, but I'd really like to know whether the data is accurate. Preventative health is important. I want to spot any problems early. That's why I'm curious if the ECG function like this actually shows anything. Alongside standard fitness features such as step counting, GPS, distance tracking, some watches now also measure blood oxygen levels, body temperatures and heart rate and even record a full ECG. Leo chooses a tracker that promises these functions. It's an Android device from a leading brand. He wants to test it out. Florian tests a different system. Many smartwatch brands now offer an ECG function. To see how reliable they are, Florian and Leo visit the cardiology clinic of Dr. Juergen Fritsch. Hello, we are registered. Do the ECG readings from the fitness trackers match those from a professional ECG at a cardiologist's office? Dr. Juergen Fritsch is a cardiologist in Cologne. He's been offering specialist sports cardiology consults for 15 years. A triathlete himself, he knows how important it is for athletes to have their hearts checked and not just at the elite level. Anyone over 35 who hasn't exercised for a long time should definitely get a medical check-up. Even seemingly healthy people can find themselves in trouble if they train too hard. And people with inherited risk factors can develop cardiovascular disease early, despite a healthy lifestyle, sometimes without realising it. A sports medical exam helps tailor training and reduce risk. The comparison is designed to show whether fitness trackers can also help identify risks. Dr. Fritsch records Leo's heart activity with a 12-lead ECG. At the same time, Leo uses his smartwatch to record an ECG. He has to hold his moistened finger on the sensor while the measurement is being taken for an accurate reading. And then it's Florian's turn. Again, the watch's sensor button must be pressed with a moist finger for 30 seconds. Then comes the all clear, no signs of arterial fibrillation. Now comes time to compare the findings. Florian and Leo can relax. Their smartwatch ECGs show no signs of arrhythmia. But are the readings accurate? We have a heart rate of 54, and that matches exactly with the watch. As far as the heart rate goes, the readings are identical. The quality of the recording is the same. Both fitness trackers impress Florian and Leo with their ECG functions. But they cannot replace an exam at a cardiologist's office. And they can't detect a heart attack. For people who only occasionally have rhythm problems or symptoms, fitness trackers are useful because you can record an ECG at any time and show it to your doctor. But they cannot detect a heart attack. And not all devices are equally reliable. Anyone with heart symptoms should see a doctor, regardless of what the watch says.

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