Study: iRhythm's Zio patch streamlines a-fib diagnosis, care, but no word yet on outcomes

By Dave Muoio
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Patients at increased risk for atrial fibrillation wearing iRhythm’s Zio patch — a  continuous ECG monitoring wearable — were more likely to have their atrial fibrillation diagnosed early and receive subsequent preventive care, according to one-year results from a late-breaking study presented at the American College of Cardiology’s annual meeting. 

The mHealth Screening to Prevent Strokes (mSToPS) trial was a joint collaboration between iRhythm, Aetna, the Scripps Translational Science Institute, with additional study funding from Janssen Pharmaceuticals, the Qualcomm Foundation, and the National Institutes of Health. 

The study, which was first announced in late 2015, provided 1,732 Aetna patients with no heart rhythm issues but moderate risk of atrial fibrillation with the patch for use over two 14-day monitoring sessions set approximately three months apart. These patients were paired two-to-one with a total of 3,476 control patients, against whom study researchers measured outcomes over the course of one year. All participants received routine care, including regular visits to a primary care physician.

"At one year, people who wore the chest monitor had nearly three times the likelihood [6.3 percent versus 2.3 percent] of being diagnosed with a-fib, and appropriately. A significantly higher proportion of these patients were started on anticoagulant therapy to lower their stroke risk compared with those who received usual care [5.4 percent versus 3.4 percent],” Dr. Steven R. Steinhubl, director of digital medicine at the Scripps Translational Science Institute and lead author of the study, said in a statement. "The data also provide a first glimpse into how this type of ECG screening might influence heart care utilization."

Along with these findings, the researchers also noted that participants who received the Zio patch had significantly more primary care physician visits as well as more cardiology outpatient visits.

However, there was no difference in emergency department visits or patient hospitalizations, with the researchers noting that there was no evidence the intervention had any impact on clinical outcomes. Steinhubl noted that despite this, the data still suggest that these patches appear to be a viable option for screening large undiagnosed populations.

"The quality of data collected through the patch is as good as what we see clinically," he said. "What was fascinating is that for the people with a-fib, the burden of a-fib (the amount of time a person was in a-fib relative to their entire monitoring time) was quite low — approximately one percent of the time on average."

Researchers will continue to follow cohort for two more years to gather more data implying changes to clinical outcomes, according to a statement.

"We hope that a digital infrastructure will help reimagine how clinical trials can be performed and that this study will be a useful template for remote enrollment and participant engagement," Dr. Eric Topol, Founder and Director of the Scripps Translational Science Institute, said in a statement. "We will have follow-up data to determine if earlier detection of a-fib translates into long-term clinical benefits, including reduction of stroke and potential cost savings."