What question did this study set out to answer?

This study evaluates the accuracy of embolic stroke classification and the rate of atrial fibrillation detection using implantable loop recorders.

May 8, 2026European Stroke JournalOpen Access

Abstract Number: Esoc2026a1269 How Well Do We Identify Af in Esus? Detection of Atrial Fibrillation in Embolic Stroke of Undetermined Source by Implantable Loop Recorder. A Cross-Sectional Study

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Why the study?

Detection of AF guides secondary stroke prevention in ESUS, and ILRs demonstrate superior detection compared to conventional monitoring. The study aimed to evaluate ESUS classification accuracy, appropriateness of ILR referral, and AF detection rates.

What is the referral rate for implantable loop recorders and the subsequent atrial fibrillation detection rate in patients with embolic stroke of undetermined source?

Key Points

This study evaluates the accuracy of embolic stroke classification and the rate of atrial fibrillation detection using implantable loop recorders.
Cross-sectional review using Irish National Audit of Stroke data on 73 ischemic stroke cases from 2024.
Stroke etiology determined using TOAST and ASCOD criteria.
Primary endpoints included ILR referral appropriateness and AF detection rates.
16 out of 73 patients were accurately identified as ESUS (mean age 67 ± 9.3 years).
Of the identified ESUS patients, 7 (44%) were referred for ILR implantation, but 5 were not referred without clear reasons.
ILR monitoring detected atrial fibrillation in 3 of the 7 referred cases (43%).

Structured PICO

What is the referral rate for implantable loop recorders and the subsequent atrial fibrillation detection rate in patients with embolic stroke of undetermined source?

Population

73 patients with ischemic stroke from the Irish National Audit of Stroke (2024), including a subset of 16 patients correctly identified as having Embolic Stroke of Undetermined Source (ESUS). Total cohort mean age 72.5 years, 59% male.

Intervention

Implantable loop recorder (ILR) referral and monitoring

Outcome

Appropriateness of ILR referral and atrial fibrillation (AF) detection rates

Implantable loop recorder monitoring in ESUS patients yields a high rate of occult atrial fibrillation detection (43%), highlighting a missed diagnostic opportunity in the substantial proportion of eligible patients who are not referred.

Implication

May reflect barriers to ILR adoption after stroke; leaves open impact of systematic referral on AF detection in prospective trials.

Abstract

Background and aims Embolic stroke of undetermined source (ESUS) accounts for approximately 17% of ischemic events. Detection of atrial fibrillation (AF) guides secondary stroke prevention. Implantable loop recorders (ILR) have demonstrated superior AF detection compared to conventional cardiac monitoring.This study aims to evaluate the accuracy of ESUS classification, appropriateness of ILR referral and the atrial fibrillation detection rate in those who underwent ILR implantation. Methods Using Irish National Audit of Stroke data a cross-sectional review was conducted on a randomized sample of 73 local ischemic stroke cases from 2024. Stroke aetiology was determined using TOAST and ASCOD criteria. Referral rates of ESUS patients for ILR implantation were reviewed. The primary endpoints were appropriateness of ILR referral and AF detection rates. Results Out of the 73 patients, (mean age 72.5 ± 1.4 years; 59% male) 16 were correctly identified as ESUS (mean age 67 ± 9.3 years). Among these, 7 (44%) were referred for ILR implantation. Of the remaining ESUS patients who were not referred, 4 had documented clinical reasons, while 5 patients had no clear reason identified. ILR monitoring detected AF in 3 of the 7 referred cases (43%). Conclusions Accurate stroke classification combined with stroke led decision making improves appropriate ILR utilization and allows for individualized secondary prevention strategies. However, a substantial proportion of ESUS patients were not referred, indicating an opportunity to improve ILR referral rates. ILR monitoring demonstrated an important diagnostic yield for occult AF in ESUS patients. Conflict of interest Tiago do Amaral: Nothing to disclose; Paul Eoin Cotter: Nothing to disclose; Natalie Maloney: Nothing to disclose.