San Francisco-based iRhythm published insights from its ambulatory ECG monitoring in more than 1 million patients in Heart Rhythm, the journal of the Heart Rhythm Society. It also presented new data for its Zio LTCM device at the American Heart Association (AHA) Scientific Sessions 2025.
Zio LTCM features a prescription-only, patch-based ECG monitor that captures up to 14 days of continuous, uninterrupted data. It also utilizes the ZEUS (Zio ECG Utilization Software) system with an FDA-cleared AI algorithm. The system delivers an end-of-wear report reviewed and validated by qualified cardiac technicians.
Findings published in Heart Rhythm demonstrated how symptom frequency influences time to arrhythmia detection. It also evaluated the correlation between symptoms and arrhythmia events. iRhythm said the study underscored the advantages of LTCM with its Zio service.
Separately, the AHA data included real-world evidence demonstrating the success of at-home patient application and activation of Zio. It also featured an independent large-scale analyses across cardio-kidney-metabolic (CKM) and chronic kidney disease (CKD) populations highlighting earlier arrhythmia detection and risk emergence across the disease continuum.
Findings published in Heart Rhythm
Data published in Heart Rhythm drew from more than 1.1 million patients who used Zio. It revealed that short-term (24-48-hour) monitoring, like with the standard Holter monitors, can miss actionable arrhythmias. This occurred even in patients reporting daily symptoms.
iRhythm said patient-reported symptoms were infrequently associated with arrhythmia events as well.
Despite previous studies showing the benefits of LTCM, the company says clinicians and payors often still prefer Holter monitoring. iRhythm said its new retrospective cohort study of Zio users saw that 20.8% had reported symptoms more than once per day. Nearly two-thirds (64%) of daily-symptom patients with actionable arrhythmias were undetected in the first 48 hours. Mean time to first detected arrhythmia exceeded 48 hours for all arrhythmia types, regardless of symptom frequency.
Less than 20% of patients documented a symptom coinciding with an arrhythmic episode, the company said. Findings highlighted the clinical value of Zio LTCM up to 14 days for identifying arrythmias.
“These findings challenge the long-held clinical assumptions and payor guidelines that frequent symptoms justify short-duration monitoring,” said Dr. Mintu Turakhia, chief medical and scientific officer and EVP of Advanced Technologies at iRhythm. “They reinforce the limitations of 24–48-hour Holter monitoring, even if patients report symptoms multiple times a day during wear, and highlight the value of Zio long-term continuous monitoring up to 14 days. iRhythm’s real-world data are contributing evidence that can help guide both clinical practice and payer policy.”
Data shared by iRhythm at AHA 2025
At AHA, iRhythm shared an analysis evaluating its home enrollment pathway for Zio service. It demonstrated that patients can successfully self-apply and activate the Zio 14-day patch-based LTCM device shipped directly to their home. They achieved high compliance with the prescribed wear duration and data quality comparable to in-clinic application.
Investigators looked at 742,268 Zio devices, comparing in-clinic and home-based applications. Median wear time and percent analyzable ECG time both came in high and comparable across groups (>13.8 days and >98%, respectively). Early wear terminations proved infrequent (≤2% for both groups).
iRhythm saw that home enrollment patients used its MyZio mobile app more often (52% vs. 17%). App use went hand-in-hand with fewer early terminations, greater analyzable time and a higher rate of compliance with return of devices for analysis within 45 days (93% vs. 80%).
Additionally, iRhythm presented three large-scale, real-world analysis providing new insights into risks emerging earlier across the CKM syndrome continuum. Data showed that arrhythmias can occur before or during early CKM syndrome stages, with risk accelerating as metabolic or kidney disease progresses.
The company said its findings identify arrhythmias as a clinically measurable signal of elevated CKM syndrome risk. It said this strengthens the case for earlier rhythm assessment to identify at-risk patients before advanced complications occur.
Other findings evaluating early predictors of chronic kidney disease (CKD) expand understanding of how arrhythmias evolve within the CKM syndrome continuum and strengthen the case for earlier rhythm assessment in at-risk populations. Along with these findings, other published data in patients with Type 2 diabetes demonstrate that arrhythmias are often first detected in acute care settings, contributing to higher healthcare costs and may be mitigated through early detection using ambulatory cardiac monitoring.
