HRS meeting: Extended cardiac monitoring improves arrhythmia detection during pregnancy

New data presented at the Heart Rhythm Society’s annual meeting (HRS 2026) in Chicago, Illinois, is shedding light on the importance of continued cardiac monitoring to detect arrhythmias in both post-catheter ablation and pregnant populations, as the first detections occurred beyond the 48-hour mark, highlighting a limitation in the traditional 24–48-hour Holter monitoring. The data was announced in a pair of poster presentations at HRS and by iRhythm Technologies, Inc.^1-3

To set the scene, in the year following catheter ablation for atrial fibrillation (AF), accurate rhythm assessment is vital for guiding anticoagulation strategies and risk stratification. A nationwide analysis of 11,051 patients who utilized the Zio ambulatory ECG device found an overall AF recurrence rate of 21%. Crucially, 26% of all patients—and 29.8% of those with paroxysmal AF—had their first recurrence detected after the initial 48 hours of monitoring. This suggests that relying on short-duration monitors could result in a false-negative rate of approximately 30% for AF recurrence.^1,2

Recent studies, such as the OCEAN trial, have utilized monitoring strategies of only 24–48 hours, which these new findings suggest may misclassify up to 1 in 4 patients with true recurrence, according to iRhythm.¹

“These data reinforce that monitoring approach and duration directly impact what is detected—and what is missed,” said Mintu Turakhia, MD, MS, Chief Medical and Scientific Officer and EVP, Advanced Technologies at iRhythm, in a statement.

“Monitoring of 48 hours or less leads to false negatives of AF recurrence in 30% of those monitored in the year following-PVI. As AF burden and recurrence increase the risk of stroke and are directly actionable for clinical decisions regarding anticoagulation, antiarrhythmic, repeat ablation, and risk of heart failure — the data are clear that 14 days should be the minimum threshold for post-ablation monitoring,” added Turakhia.

Potential impact of short monitoring duration in pregnant populations

In a retrospective cohort of pregnant patients specifically—presented as the “Detection of Atrial Fibrillation Recurrence and Monitoring Duration on Ambulatory Cardiac Monitoring” poster at HRS—analysis revealed that rhythm abnormalities occur even in the absence of structural heart disease. Arrhythmias were detected in 37.7% of pregnant patients, with 62.8% evaluated for symptoms like palpitations. Clinically significant arrhythmias—including AF, supraventricular tachycardia (SVT), and heart block—were present in 13.6% of patients. Notably, 59.6% of all arrhythmias and 66.7% of clinically significant events were only identified after the first 48 hours of monitoring.^1,3

The median analyzable time was 99.2%, “indicating that nearly all recorded monitoring time produced usable heart rhythm data,” stated iRhythm.¹

“Physiologic changes during pregnancy increase arrhythmia risk, with implications for both maternal and fetal health,” said Ridhima Kapoor, MD, Clinical Assistant Professor of Cardiovascular Medicine at Stanford University, and an investigator on the study and its presenting author, in a news release.

“This analysis demonstrates that arrhythmias occur in more than one-third of pregnant patients, with clinically significant events in nearly 1 in 7. Notably, the majority were identified after 48 hours of monitoring. This underscores the importance of extended cardiac monitoring to accurately capture arrhythmia burden and guide management."

These findings support a broader movement in clinical practice toward 14-day continuous, patch-based monitoring. Further supporting this shift is a large-scale analysis of more than 1,000,000 patients published in Heart Rhythm in February 2026, which found that 48-hour monitoring can miss actionable arrhythmias even in symptomatic patients.⁴

References:

1. New Data Presented at HRS 2026 Show Short-Term Holter Monitoring Misses a Large Proportion of AF Recurrence Post-Ablation and Clinically Significant Arrhythmias in Pregnancy. iRhythm Holdings, Inc. News release. April 27, 2026. Accessed April 28, 2026. https://irhythm2024rd.q4web.com/news/news-details/2026/New-Data-Presented-at-HRS-2026-Show-Short-Term-Holter-Monitoring-Misses-a-Large-Proportion-of-AF-Recurrence-Post-Ablation-and-Clinically-Significant-Arrhythmias-in-Pregnancy
2. Turakhia MP, Schmitt S, Fokin V, AShburner JM, Battisti AJ. Detection of Atrial Fibrillation Recurrence and Monitoring Duration on Ambulatory Cardiac Monitoring. Poster. Presented at: HRS 2026. April 23-26, 2026. Chicago, Illinois.
3. Kapoor R, Vatankhah N, Schmitt S, Fokin V, Battisti AJ, Turakhia MP. FREQUENCY OF CARDIAC ARRHYTHMIA DETECTION ON EXTENDED AMBULATORY CARDIAC ECG MONITORING DURING PREGNANCY: RESULTS FROM A LARGE NATIONAL SAMPLE. Poster. Presented at: HRS 2026. April 23-26, 2026. Chicago, Illinois.
4. Battisti AJ, Pinkerton R, Fokin V, et al. Relationship of symptom frequency and symptom-rhythm correlation to arrhythmia type and time to detection: Insights from ambulatory electrocardiogram monitoring in over 1 million patients. Heart Rhythm. doi:10.1016/j.hrthm.2025.11.007