New data from iRhythm Technologies has demonstrated that extending the cardiac monitoring duration for arrhythmia recurrence to 14 days resulted in a more complete clinical assessment in post-ablation and pregnancy patient populations.
Monitoring for the recurrence of arrhythmias with Holter monitors is not currently standardised, but 24-48 hours is a commonly employed monitoring duration window following cardiac ablation for atrial fibrillation (AF) and in monitoring arrhythmias throughout pregnancy.
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Data from both studies was presented at the 2026 Heart Rhythm Society’s (HRS) annual meeting, held between 23-26 April in Chicago.
One of the datasets was a retrospective analysis of 11,051 post-AF patients who were monitored for 14 days with iRhythm’s Zio, a wearable ambulatory electrocardiogram (ECG) patch. In the group, which was monitored in the year following AF ablation, the overall recurrence rate of AF was 21%.
A substantial proportion of AF recurrence was detected beyond 48 hours and within 14 days, as per iRhythm’s data.
With up to 14 days of continuous monitoring with Zio, 26% of patients experienced their first detected AF recurrence beyond 48 hours. The findings indicate that reliance on short-duration Holter monitoring would miss AF recurrence in a ‘considerable proportion’ of post-ablation patients, iRhythm stated.
According to iRhythm, the overall data suggest that up to one in 4 patients with true AF recurrence could be misclassified as a false negative with short-duration Holter monitoring versus 14 days with the company’s Zio patch.
Noting that the data suggest a reliance on short-term monitoring in clinical practice may result in missed AF recurrence, iRhythm highlighted that this factor has clinical implications for anticoagulation discontinuation based on recent studies, including the OCEAN trial (NCT02168829).
The OCEAN study evaluated whether successful catheter ablation for AF eliminated the need for long-term oral anticoagulant therapy, and used a sequential cardiac monitoring strategy of 24-48 hours.
Mintu Turakhia, iRhythm’s chief medical and scientific officer and executive vice president for advanced technologies at iRhythm, said: “These data reinforce that monitoring approach and duration directly impact what is detected – and what is missed.
“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.”
A separate retrospective cohort study by iRhythm of 486 pregnant women undergoing extended ambulatory ECG monitoring yielded similar benefits for 14-day monitoring for arrhythmia recurrence.
Arrhythmias were present in one in seven of these patients, with almost 60% of overall arrhythmias, and 66.7% deemed clinically significant, first detected after 48 hours.
“Physiologic changes during pregnancy increase arrhythmia risk, with implications for both maternal and foetal health,” said Ridhima Kapoor, clinical assistant professor of cardiovascular medicine at Stanford University and an investigator on the study.
Given that the analysis demonstrated that arrhythmias occurred in more than one-third of pregnant patients, the findings underscore the importance of extended cardiac monitoring “to accurately capture arrhythmia burden and guide management”, Kapoor added.
