The Apple Watch can detect a leading cause of heart attacks — an unadvertised capability that could have big implications for health monitoring — according to a Dutch doctor.
After using the Apple Watch’s electrocardiogram feature, Dr. Ruud Koster, a cardiologist from Amsterdam, accidentally discovered that he had a potentially fatal heart blockage that caused myocardial ischemia. The doctor wrote a paper about his experience and now recommends that the Apple Watch be studied for its ability to alert wearers about potentially deadly heart blockages.
Apple Watch ECG can detect potentially fatal heart blockages
Photo: Dr Rudolph W. Koster
The Apple Watch’s health and fitness features have been cited numerous times for saving lives, frequently by alerting wearers to undiagnosed health problems. Newer Apple Watch models include an electrocardiogram (ECG) feature that medical studies have shown can reliably detect atrial fibrillation and other heart rhythm problems. The Mayo Clinic used the Apple Watch ECG and AI to find undetected heart pump problems.
But the Apple Watch has not yet been approved for detecting myocardial ischemia — a lack of blood and oxygen to the heart muscle typically caused by blockage of coronary arteries. Myocardial ischemia is a leading cause of fatal heart attacks, responsible for more than 1 million deaths a year in the United States alone, according to the Cleveland Clinic.
In fact, Apple’s support page clearly states that “Apple Watch cannot detect heart attacks. If you ever experience chest pain, pressure, tightness, or what you think is a heart attack, call emergency services immediately.”
However, Koster said his Apple Watch can detect myocardial ischemia. “The use for detecting myocardial ischaemia is not endorsed by Apple but is documented in this case,” he wrote in a recently published case report.
No symptoms of heart disease
Prior to his Apple Watch discovery, Koster had no idea he had a potentially fatal heart blockage. He suffered no discomfort or any symptoms of heart disease. “Before, during, and after the episode, he was completely asymptomatic for chest pain, shortness of breath, dizziness, or palpitations,” the paper says.
After exercising on a cross-trainer at the gym, Koster ran an Apple Watch ECG on himself out of curiosity. (It’s a 30-second test: Here’s how to perform an ECG on Apple Watch.) While looking at his ECG results, Koster noticed a small “T-wave” dip at the end of the trace. As he continued to run ECGs on himself for the next half hour, he noticed how the T-wave dip got bigger after a few minutes, then returned to normal after about 30 minutes.
A cardiologist with 50 years of experience, Koster recognized the dip as a sign of a “silent” blockage, which doesn’t lead to any symptoms of heart disease. (He does have a family history of heart disease and was being treated for high cholesterol.)
Koster immediately consulted another cardiologist. Soon afterward, he underwent an in-depth heart exercise test using a medical ECG. The lab ECG confirmed the blockages, and Koster underwent heart bypass surgery to treat three blocked arteries. After the successful surgery, he recovered without any problems. His ECG is now normal.
Further study needed
Koster said in his paper that the Apple Watch can reliably detect heart blockages. However, the wearer must remain perfectly still during the 30-second test.
“We demonstrated that the lead 1 ECG made with the Apple Watch can reliably record T-wave changes indicating myocardial ischaemia,” he wrote.
Now, Koster is calling for more studies. “The use of the Apple Watch to document ischaemic changes should be studied systematically for its potential to identify myocardial ischaemia, mainly triggered by symptoms but maybe for asymptomatic persons as well,” he wrote.
Apple didn’t respond to Cult of Mac’s request for comment.
In the future, the Apple Watch could provide early diagnosis of heart problems, Koster said. If an Apple Watch wearer experiences chest pain, they could take a careful ECG and send a PDF of the results to their cardiologist. However, he warned of the potential for false positives. To guard against those, Koster called for “rigorous validation” before using Apple Watch in a clinical setting.
Koster noted that his Apple Watch detected his silent, asymptomatic heart problems. And he said the smartwatch should have no trouble identifying similar problems in people with pronounced symptoms.
If wearers can sit still and the Apple Watch can collect good ECG data, this could become a big breakthrough in the detection of heart disease. Millions of people own ECG-capable Apple Watches and similar devices, and can test themselves to their heart’s delight at home. Apple Watches may even gain AI-powered algorithms to look for subtle signs of disease over time.
