Heart Doctor is concerned about this Apple Watch feature

As a heart doctor, my opinion is that if you think an Apple Watch is nifty, buy one. But do not buy it for your health. It will not improve your health, and it could even bring you harm.

Dr. John Mandrola, Cardiac Electrophysiologist at Baptist Health Hospital in Louisville, Kentucky, USA

When Apple introduced the Apple Watch Series 4 last month, the wearable received a great deal of coverage for being the first smartwatch to feature an electrocardiogram (ECG). An ECG is essentially a heart monitor that is able to detect irregular patterns in the wearer’s heartbeat that could indicate an impending heart attack or stroke.

This is some serious tech packed in a device that sits on your wrist. Even more impressive is that the Apple Watch 4 has gotten FDA clearance to function as an ECG. The watch even received an endorsement from the President of the American Heart Association.

But a heart doctor has raised concerns that the ECG built-into the Apple Watch 4 may not be as accurate as the ECG machines used in hospitals. 

Dr. John Mandrola, a Cardiac Electrophysiologist at Baptist Health Hospital in Louisville, Kentucky, USA, recently wrote that he is concerned that the one-lead ECG used in the Apple Watch 4 may not be as accurate as medical grade ECG used in hospitals. Typically, these hospital-grade ECG uses twelve leads resulting in a more accurate reading. He mentioned that the watch might not be sensitive enough to discern the difference between low-risk atrial fibrillation (AF) that does not need to be treated and AF that requires medical attention.

AF is an irregular and often rapid heart rate that could increase your risk of stroke and other heart related complications.

“The first obstacle when it comes to AF screening is understanding that the vast majority of people do not have AF, but most people do have heart-related normal variation of their heart rhythm, which can mimic AF.” the doctor said in his post on CNBC.

This makes ECG accuracy a critical point.

In theory, having an ECG on your wrist appear to be a good idea, as it allows for AF early detection but in practice, the watch could flag normal or low-risk AF as a serious condition.  

The accuracy of an ECG is around 90 percent. This is good for those who do have a heart problem. But what about the 10 percent irregular heart rhythm that are actually low-risk that may be falsely labelled as AF? Dr. Mandrola says that misdiagnoses “will exert a massive effect in large populations—like the millions of people who may soon own the new Apple Watch.” 

“To put this into perspective, let’s use a round number of 1 million watch owners. We know that about 1 percent, or 10,000 people, will have AF, and 990,000 will not have AF. If the watch is wrong 10 percent of the time, that means nearly 100,000 people will be falsely diagnosed with AF.” He added.

This will result in many people being subjected to unnecessary tests and these tests and procedures could also be harmful for the patient.

“Since all medical interventions come with risks, many people will suffer harm from unnecessary tests and procedures.” he said. 

Another snag in heart rhythm screening stems from a poor understanding of AF. Despite decades of research, doctors still argue about the causes of AF and its treatments.

“The truth is that preventive health is far more complicated than identifying irregular rhythms from a watch.” He concluded in his post.

Read the full article from Doctor Mandrola here.