Wearable tech: Can your Apple watch detect COVID-19?

“I’m having runs of SVT,” she told me.

“Palpitations and shortness of breath, like last time?” I asked her. She was one of our regulars, the kind who, when their address appears on our data terminal, I can have my ePCR halfway completed before I even arrive at the scene. The only thing that kept me from doing so was the fact that I had to arrive at the scene to determine whether it was her or her mother.

This wasn’t our fortieth rodeo in the past couple of years, much less the first. Most of the time, the episode had passed before we arrived at the scene, but still she wanted to go to the ED anyway, a whopping 0.3 miles away. She was getting perturbed with the local ED because they couldn’t give her any answers. I couldn’t blame them. It’s hard to diagnose an asymptomatic patient.

“Not really,” she shrugged, holding up her left wrist. “My watch notified me. Three times in the past couple of hours. The last time, my heart rate got up to 190. It just quit before I could get short winded. Lasted maybe a minute.”

I cocked a skeptical eyebrow. It’s not often a patient can provide me with verifiable, objective data to back up their complaint. But there it was, a notification on her Apple Watch that her heart rate had inexplicably risen to 190 beats per minute while at rest, and just as quickly subsided.

A 12-lead ECG performed a couple minutes later noted sinus rhythm at 76 beats per minute. There wasn’t a bit of ectopy or a hint of ST segment elevation. She was, once again, asymptomatic.

“Well,” I shrugged, “Missed it again. Take my hand, and step up into the rig and we’ll …”

“Nah, I’ll just see my cardiologist next week,” she demurred. “I called 911 when it notified me because I figured it wasn’t going to stop.”

She went on to tell me she had – finally, after much nagging from ED and EMS staff – seen a cardiologist, who had recommended she buy an Apple Watch. She had even captured a Lead I snippet by touching the crown of her watch with her other hand.

My partner was duly impressed, but I adopted a studied air of nonchalance as we drove back to the station. “Yeah, they can do that,” I told him. “They can even detect falls and call 911 for you.” I didn’t tell him she was the first patient I had encountered who had actually used her Apple Watch for that purpose since I wrote about it a couple of years ago.

In that article, I noted how the Series 4 Apple Watch utilized photoplethysmography to detect abnormal heart rates and rhythms as well as a sensor in the crown to replicate a Lead I tracing by touching the crown with your other hand, and used its gyroscope and accelerometer coupled with data from a movement disorder clinic to accurately detect falls. At the time, Apple was partnering with researchers from Stanford University to determine if its watch could accurately identify atrial fibrillation. That study has been concluded, with equivocal results. The watch did detect atrial fibrillation accurately in 34% of participants aged 29-39 and 35% of participants over age 65. There was a significant time lag – 13 days, on average – between the notification and EKG confirmation of the arrhythmia, and 57% of participants contacted healthcare providers not participating in the study, but as proof-of-concept, the study was a success. Future studies will hopefully control for some of those variables.

Expanding healthcare apps and applications

As device manufacturers continue to explore the potential of wearable tech, we’re discovering new applications and opportunities for health monitoring. Toronto’s University Health System is partnering with Apple to research the utility of its pulse oximetry app, coupled with its arrhythmia-detecting capability, as an early detection tool for signs of heart failure. Congestive heart failure is a terminal diagnosis – 50% of those diagnosed will be dead within five years – so early detection has the real potential to save lives.

And now, we’re learning that wearable tech has the potential to detect COVID-19. Mount Sinai Medical Center researchers have used an Apple Watch to measure heart rate variability as an early-detection system for COVID-19. It’s certainly plausible; an inflammatory response triggers physiologic changes in vital signs such as heart rate, respiratory rate and blood pressure. The changes are minute enough that they may escape our detection until we become actively symptomatic, but for a computer microprocessor and a detection algorithm, it’s a snap. Mount Sinai researchers are also using Apple Watch physiologic data along with a questionnaire in a paired smartphone app to monitor psychological well-being among its staff dealing with the coronavirus pandemic.

On June 18, 2020, pro golfer Nick Watney became the first member of the PGA Tour to be diagnosed with COVID-19. Watney had just completed the first round of the RBC Heritage tournament in Hilton Head, South Carolina. He went to bed essentially asymptomatic and woke up feeling fine, but was alerted of a significant rise in his sleeping respiratory rate – from 14 to 18 – via an app on his smartphone. The app, Whoop, uses a sensor-laden wrist strap much like a watch band to track physiologic data for athletes, and its respiratory rate monitoring feature alerted Watney of a change in his respiratory pattern that he didn’t notice himself. Testing later that morning confirmed COVID-19, and Watney was able to withdraw from the tournament and quarantine before he came into contact with anyone. He had tested negative a mere two days before.

We’re only beginning to explore the potential of wearable tech. As the capabilities increase, we may find ourselves reminding our EMT students to check the patient’s watch rather than look for Medic Alert bracelets during our physical examination. The watch certainly has the potential to tell us more than a bracelet ever could.