Conference Coverage

Heart rhythm data from wearables confounds EP practice



Cardiac electrophysiologists are at a loss about how to manage people who bring them smart-watch ECG recordings or other warnings that flagged a possible cardiac arrhythmia.

Dr. Mintu P. Turakhia, executive director, Center for Digital Health, Stanford (Calif.) University Mitchel L. Zoler/MDedge News

Dr. Mintu P. Turakhia

While the clinical community has yet to reach an evidence-based consensus on how to deal with this information, or even asymptomatic arrhythmias identified by more standard means, the American public is voting with their wrists. People seem to like collecting and reviewing readouts on their heart rhythm and other vital data, and then they often take their numbers to a physician, especially when their device suggests a possible problem.

“The whole paradigm of ordering a test only if you intend to act on the result has been flipped. People now get what they want directly, and our job is to guide them” after the fact. “You need to teach people what’s actionable and what’s not,” Mintu P. Turakhia, MD, said at the annual International AF Symposium.

“We’re in a situation where the ability of a sensor to detect things is separate from access to the health care system. They are no longer coupled; they are disjointed. People can create their own ICU in their house just by shopping online, but what do we do with this information, whether it’s an irregular heart rhythm or their whole genome?” asked Dr. Turakhia, executive director of the Center for Digital Health at Stanford (Calif.) University and director of cardiac electrophysiology at the VA Palo Alto (Calif.) Health Care System.

“The main challenge is people without a diagnosis who get a notification. How much monitoring should you do until you can say it was a false positive? We don’t know what to do, so we monitor them. People are trying to figure this out.” Dr. Turakhia said. Some people who seek out electrophysiologists this way “may not even have a primary care physician,” he noted.

The potential implications of widespread monitoring for heartbeat irregularities in the general public began to surface in a study that Dr. Turakhia helped run that collected wearable data from nearly 420,000 Americans. Results from the Apple Heart Study showed that, during a median 117 days of monitoring with a smart watch, 2,161 people (0.5%) received a report of an irregular pulse, which led to further investigations that eventually diagnosed atrial fibrillation (AFib) in 153 people of the 450 who underwent follow-up assessment (N Engl J Med. 2019 Nov 14;381[20]:1909-17). These results “raise questions” about the large number of people who underwent follow-up testing who did not have arrhythmia, Dr. Turakhia noted.

Dr. Jeremy N. Ruskin, professor of medicine, Harvard Medical School, Boston Mitchel L. Zoler/MDedge News

Dr. Jeremy N. Ruskin

“The dissemination of wearables has been quite dramatic, and electrophysiologists end up owning this,” commented Jeremy N. Ruskin, MD, professor of medicine at Harvard Medical School and director emeritus of the cardiac arrhythmia service at Massachusetts General Hospital, both in Boston. “I get a ton of calls from people whom I wish never bought a smart watch, and they say ‘I have atrial fibrillation. What do I do?’ ”

To document the growth of this trend, Dr. Turakhia cited results from a survey he collaborated on, run by Stanford and Rock Health, that found a 33% ownership rate among American adults of a wearable device capable of collecting health data, and a 42% rate of people who tracked their health data with a device, app, journal, or log. Both of these rates more than doubled what a similar survey found in 2015.

The cardiac electrophysiology community took a first step toward addressing one aspect of this evolving situation. In early 2020, the Heart Rhythm Society and the Consumer Technology Association jointly issued a guidance document targeted at consumers that walks them through the kinds of information their wearable devices might collect and how to approach this information. The main message: If you have questions or concerns about your data, consult a clinician. What remains in short supply is guidance to clinicians on what to do when they see these patients.

Dr. Daniel E. Singer, professor of medicine, Harvard Medical School, Boston Mitchel L. Zoler/MDedge News

Dr. Daniel E. Singer

“Until recently, device-detected AFib was the sole purview of electrophysiologists using implanted rhythm-monitoring devices. Now mobile and other devices raise issues [of asymptomatic AFib] for a much broader population,” noted Daniel E. Singer, MD, professor of medicine and epidemiology at Harvard and Massachusetts General Hospital. “The world of device-detected AFib now includes watches.”

Researchers have tried for years to better understand the stroke risk faced by patients with asymptomatic or subclinical AFib that’s detected by an implanted device, as in the ASSERT study of nearly 2,600 patients followed for a median of 2.5 years that found an increased stroke risk when the duration of individual, subclinical AFib episodes surpassed 24 hours (Eur Heart J. 2017 May 1;38[17]:1339-44). More recently, a study of AFib duration collected by implanted cardiac devices in nearly 22,000 Americans showed a relationship between stroke risk and both the duration of AFib episodes and the underlying risk of a person for stroke as measured by their CHA2DS2-VAScscore (Circulation. 2019 Nov 12;140[20]:1639-46). Just under 30% of patients in the study were diagnosed with AFib at entry.

The implications of asymptomatic episodes of AFib have so far been largely studied in people with an implanted cardiac device, which may have limited applicability to wearable users. In addition, the field has not yet fully sorted out the relationships between the duration of individual AFib episodes and overall AFib burden, and a person’s stroke risk and the window of time when the potential stroke-preventing benefits of anticoagulation outweigh its bleeding risk.

The results of trials now in progress that are examining the safety and efficacy of medical interventions designed to avert strokes in patients with asymptomatic AFib “will bear on the use of anticoagulants in a large group of patients,” including people with AFib detected by a wearable, Dr. Singer predicted.

The Apple Heart Study was sponsored Apple. Dr. Turakhia has received funding from Apple, and he has received honoraria or research funding from several other companies. Dr. Ruskin has been a consultant or adviser to several companies, is a steering committee member for Pfizer, and holds equity or options in Portola, Element Science, NewPace, Gilead, and InfoBionic. Dr. Singer has been a consultant and adviser to Boehringer Ingelheim, Bristol-Myers Squibb, Johnson & Johnson, Merck, and Pfizer, and he has received research grants from Bristol-Myers Squibb.

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