Subclinical Atrial Fibrillation Detection: Holter vs Insertable Cardiac Monitor

Holter Monitor Cardiac Arrhythmia
Holter Monitor Cardiac Arrhythmia
Continuous monitoring with an insertable cardiac monitor was found to be superior at detecting subclinical atrial fibrillation compared with a Holter monitor.

Continuous monitoring with an insertable cardiac monitor (ICM) is superior to intermittent monitoring with a Holter monitor for identifying subclinical atrial fibrillation (AF) in at-risk patients, according to a study published in JACC: Clinical Electrophysiology.

In this small study, investigators evaluated outcomes associated with continuous ICM vs intermittent monitoring with a 72-hour Holter monitor in 82 patients (median age, 71.3 years) with diabetes and hypertension. Exactly 16 days following participant inclusion, an ICM was administered to all patients. Comparisons were made 1 month following insertion of the ICM.

The primary end point was AF incidence lasting at least 2 minutes as measured by ICM and at least 30 seconds as measured with Holter monitoring.

The majority of subclinical AF cases were observed at 1 year. At follow-up, an ICM was able to detect subclinical AF in a total of 17 patients. Monitoring with an ICM detected AF lasting at least 2 minutes, thus achieving the primary end point. The median detection time for the first episode was 91 days.

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Comparatively, intermittent monitoring with a 72-hour Holter monitor detected AF episodes in 2 patients. Overall, continuous ICM monitoring was deemed superior to Holter monitoring for detection of AF.

A subclinical AF incidence of 20.7%, which was found in this cohort, may have been underestimated due to both the storage capacity and detection algorithm of the ICM. Also, because this study was specific to patients who were at least 65 years old and had diabetes and hypertension, the findings cannot be generalized to other high-risk patient populations.

The findings suggest that patients with hypertension and diabetes are at risk for subclinical AF, and these results indicate “that this population with a substantial risk [for] thromboembolism should be taken into consideration when discussing relevant patient populations for AF screening.”


Philippsen TJ, Christensen LS, Hansen MG, Dahl JS, Brandes A. Detection of subclinical atrial fibrillation in high-risk patients using insertable cardiac monitor [published online November 1, 2017]. JACC Clin Electrophysiol. doi:10.1016/j.jacep.2017.06.020