Clinical guidelines play catch-up
Ironically, the HRS has issued this guidance to the public and has told people to take their wearable-collected heart data to clinicians before the HRS or any other medical group has advised clinicians on how they should handle, interpret, and use heart rhythm data collected this way.
Presumably, many if not most of the people with questions about their heart data from wearables are asymptomatic, because symptoms are what usually drive patients with a cardiac arrhythmia to consult a physician – they don’t wait to see what their device tells them. But the best way to manage asymptomatic arrhythmias like atrial fibrillation (AFib) remains a big clinical uncertainty today, with no evidence base as a guide, although several studies exploring this question are in progress.
“There are no clear and definitive data showing that treating subclinical atrial fibrillation improves outcomes. That’s what we need, and until we get these data you won’t see strong recommendations in guidelines” to screen patients for asymptomatic AFib or other arrhythmias, said, a cardiac electrophysiologist and professor of medicine at Duke University, Durham, N.C., during the 2019 American Heart Association scientific sessions in Philadelphia in a talk about wearables and guidelines.
“If you intervene with silent AFib, do you improve outcomes? That evidence is lacking,” she said. Another shortcoming of current evidence is a clear understanding of what AFib burden warrants intervention, added Dr. Al-Khatib. “We see high-rate AFib episodes recorded in patients with implanted cardiac devices [and no symptoms], and we don’t know what to do with that either.”
The closest any existing guideline from a medical society comes to currently endorsing screening for AFib by a wearable is the 2016 European Society of Cardiology’s AFib management guidelines, which give “opportunistic screening” among people aged older than 65 years a IB recommendation, but specifically for screening by taking a patient’s pulse or with a ECG recording, with no mention of the screening role for wearables (), Dr. Al-Khatib noted.
The most extensive data on screening for asymptomatic AFib in an unselected population came in the recently reported results from the, which enrolled more than 419,000 people monitored by a smart watch for a median of 117 days. During this screening, 2,161 people (0.52%) received a notification of having an irregular pulse (including 3.1% of those who were aged at least 65 years), which triggered more intensive assessment with an ECG patch for a median of 13 days in 450 of the 2,161 screening positives (21%) who agreed to participate in this follow-up. Among those 450 people, the patch test identified 34% as having actual AFib ( ). But while this study provided evidence that screening for an irregular heartbeat with a wearable can identify AFib with some level of success, the results did not address whether this approach improved short- or long-term patient outcomes.
In addition, what the Apple Heart Study results showed was that this sort of screening results in a relatively large volume of follow-up testing. Of the 2,161 participants who received an irregular pulse notification, 1,376 (64%) returned a 90-day survey. Of these, 787 (57%) reported contact with a health care provider outside the study, 28% were prescribed a new medication, 33% were recommended to see a specialist (such as a cardiologist), and 36% were recommended to have additional testing.
“The results raise the question that a lot of resources were used,” to assess patients with a positive screening result, noted, a cardiologist and professor of medicine at Stanford (Calif.) University who studies quality of care for patients with heart disease. He estimated that, in the Apple Heart Study, each of the more than 2,000 patients who screening positive for an irregular heartbeat and underwent subsequent assessment ran up about $700 worth of follow-up testing. But he added that, in the case of AFib, the primary intervention that many previously undiagnosed AFib patients receive is some sort of anticoagulation for stroke prevention. Moreover, because this intervention is so effective there is a lot of money to play with to make AFib screening cost effective, as judged by typical, contemporary metrics of cost efficacy that value a quality-adjusted life-year (QALY) gain as reasonable for society to pay if the cost of an incremental QALY is $50,000-$150,000.
If the benchmark is a cost that’s within $50,000/QALY, then an average follow-up cost of $116/person to assess screened positives can fall within this cost ceiling. If the benchmark is $150,000/QALY, then follow-up costs can run as high as $491/person screened, said Dr. Heidenreich during the same AHA session where Dr. Al-Khatib spoke last November.
Despite this good news for screening for AFib with a wearable from a cost-effectiveness perspective, “there is so much uncertainty regarding the benefit and the consequences of incidental findings that we need an outcomes study before widespread implementation” of this type of screening, Dr. Heidenreich concluded. “We need an outcomes study to feel comfortable” with screening. “There is a huge potential for extra care that we don’t understand.”
Dr. Marrouche agreed that collecting adequate evidence to drive changes in clinical guidelines on how to use data from wearables has lagged behind the rapid spread of wearables and the information they can produce among the American public. “Outcomes and evidence will support guidelines development, but in the meantime, we’re offering education to clinicians, patients, and consumers. Consumers own their data, and they can share them with whomever they choose.”
The document notes that people who use wearables are, in general, “enthusiastic about tracking their data, not only for their own use, but also to share” with others, often on social media websites.
“We cannot control that, but our goal in the document is focused on the clinical relevance [of the data] and to help people better understand their data and use it in a meaningful and safe way,” Dr. Marrouche said.
Dr. Marrouche has been a consultant to, advisor to, or received research support from Abbott, Biosense Webster, Biotronik, GE Healthcare, Medtronic, Preventice, Sanofi-Aventis, Siemens, and Vytronus. Ms. Wurster is an employee of the Heart Rhythm Society. Dr. Al-Khatib has been a consultant to Milestone Pharmaceuticals and Medtronic, and she has also received other financial benefits from Medtronic. Dr. Heidenreich had no disclosures,