What The Apple Watch ECG Features Can Really Tell You About Heart Health

When Apple announced the Apple Watch Series 4 last September, the spotlight was on its exciting new health features, namely, an FDA-approved electrocardiogram sensor, aka "ECG." By simply touching the watch's Digital Crown, users could measure their heart rhythms and even pick up on atrial fibrillation (AFib), a heart abnormality that causes an irregular heartbeat.

It was groundbreaking technology, especially for the millions of people who have AFib in the United States, but the announcement left some people with questions: Is the watch presenting too much complicated information? Do you really need to have an ECG in your watch? And will having this sensor cause a lot of undue anxiety for people?

Anxiety is something that Apple thinks about a lot, says Sumbul Desai, MD, vice president of health at Apple, at a Today at Apple event in Brooklyn. "Anxiety comes from not knowing," she says. "If you have the education, information, understanding, and context of what that information means, and potentially what you can do about it, I think that really diminishes anxiety." That's one reason why the ECG app includes such detailed instructions and warnings before you try it. But the bottom line is that "we don’t surface data that we don’t think is actionable," she says.

As an Apple Watch-wearer and person who has some health concerns, I've personally played around with the ECG feature just because I'm curious — and it's kind of fun. Dr. Desai says that's not really the point: "As a physician, we don’t ever want you testing unnecessarily, so we definitely don’t want you just taking your ECG all day, because thats not what you're supposed to do," she says.

So, what is the fancy heart feature for? In honor of American Heart Month, we've answered a few questions you may have about how the Apple Watch's heart features fit into your own healthy lifestyle:

Besides knowing your family health history and own personal risk factors, Dr. Desai says young people should understand that their health today impacts health later on in life. Millennials should care about — or at least engage in — healthy habits that will ultimately lead to good heart health, meaning, eating well, exercising, and focusing on your overall mental health and stress, she says. "For those who have heart problems later in life, I can’t tell you how frequently I hear from patients who say, I wish I had done that differently a number of years ago."

The heart has its own "electrical system," just like a house, that controls its rhythm, John Rumsfeld, MD, PhD, chief innovation officer for the American College of Cardiology, with a focus on digital health, explained at the Apple event. "Normally, it’s a slow, steady beat, like a rock beat," he said. But for people with AFib, which is an irregular rapid beat of the heart, it's as if your "heart's electrical system went into free form jazz," he said. This is dangerous, because AFib usually is asymptomatic, meaning you can't feel it happening, and it can lead to a stroke or in some cases, heart failure.

Scary? For sure. According to the Centers for Disease Control (CDC), an estimated 2.7 to 6.1 million people in the United States have AFib, but only 2% of people younger than age 65 have AFib. Someone who experiences AFib and wears an Apple Watch (with the irregular heartbeat notifications turned on) could theoretically detect when they're in AFib, and then take that data to their doctors. "This is just meant to be a way to capture that information in that moment, so that you can go in and have a conversation with a doctor to understand what was going on," Dr. Desai says. "We don’t want people to diagnose off of it. We don’t think it’s the full picture of your heart, it's just a subset of what's going on in your heart."

The reality of the healthcare system is that not every doctor and clinician is up-to-speed on the latest trackers or technology, so they might not be totally perceptive to your Apple Watch data. "Medicine's going to need to catch up, because we're not there right now," Harlan Krumholz, MD, cardiologist and health care researcher at Yale University and Yale-New Haven Hospital said at the Apple event. But, he's hopeful that other doctors are opening up to the idea: "The discussions now are ongoing, because people are realizing there's real value in the data patients are generating."

If nothing else, your Apple Watch could be a way to facilitate a conversation with your doctor about what your current lifestyle is like outside of what you divulge to your doctor in the appointment. "[A doctor's visit] doesn’t enable us to really have a picture of what your life is like, or what's going on with you," Dr. Krumholz said. "These sensors, watches, and other devices that are going to be developed will enable us to have a fuller picture."