Apple’s watch monitors your heart rate and can send you notifications if it detects a problem. In particular, the Apple Watch can alert you when it detects symptoms of atrial fibrillation, a heart rhythm disorder that can be dangerous and require medical intervention. It’s a great feature, but it’s not necessarily as secure as you’d think.
Apple is not hiding from it, the manufacturer takes care to explain that the Apple Watch is not a medical device and that it can report a problem, but it is not necessarily the case. In this technical sheet, we can read:
Apple Watch does not constantly check for atrial fibrillation. As a result, Apple Watch cannot detect all instances of atrial fibrillation, and some people may not receive notifications during an episode of atrial fibrillation.
This precaution is important, because indeed, the Apple Watch is not foolproof, as recalled Fortune. For starters, detection of atrial fibrillation only works between 50 and 120 beats per minute (BPM), as Apple said in this document provided to the FDA, the US medical authority that approved the function in the States -United. Problem, a third of known cases of atrial fibrillation appeared above 120 BPM according to a Finnish study of 2015.
For at least a third of the proven cases, the Apple Watch would have detected nothing at all because of this technical limitation. Perhaps a future version of the watch will improve this point and be able to better manage the range of heart rhythms where atrial fibrillation generally appears, up to 175 BPM according to the Mayo Clinic. Even then, there is still room for improvement in the detection processes, which are apparently far from complete.
Another study has just been published by Circulation, an American cardiology publication. She is investigating the accuracy of the detection of atrial fibrillation in the Apple Watch Series 4 in a group of 50 patients who have had a cardiac surgical operation. This population suffers significantly more often than the average from an irregular heartbeat. During two days, each patient measured his heart rate three times with the Apple watch and with a specific medical device.
After measuring the heart rates of these patients, the Apple Watch correctly detected atrial fibrillation 34 times, compared to 90 known cases identified with medical equipment. That makes a success rate of only 41%, which means that 59% of the cases were not detected by the watch. The problem in this case is not so much the hardware as the software. While watchOS only detected 41% of cases, the ECG generated by the watch and analyzed by a cardiologist was significantly more reliable: 96% of these atrial fibrillations correctly detected.
Depending on whether you are used to seeing a glass that is half empty or half full, you may think that the Apple Watch misses the majority of cases of atrial fibrillation and that Apple should stop promoting this function. . Or when the watch created by Apple can detect 40% of heart problems, “free” since it is not its primary function.
In any case, the most important advice to remember is that Apple Watch can help, but it doesn’t replace a real specialist. If you have any doubts, go see a cardiologist before buying a watch …