Atrial fibrillation detected by external loop recording for seven days or two-day simultaneous Holter recording: A comparison in patients with ischemic stroke or transient ischemic attack

•This study highlights a clinically important problem, using ELRs to detect short episodes of AF.•The primary strength of this study is simultaneous Holter recording and ELR monitoring.•Investigators analyzing the ELR tracings were blinded to the Holter recording results and vice versa.•86% of patients with ELR-classified AF were false positives.•Automatically ELR-detected AF episodes should be used very cautiously in clinical decision-making.

Atrial fibrillation (AF) is the most common cardiac cause of ischemic stroke and transient ischemic attack (IS/TIA).AimTo compare the diagnostic value of seven-day external loop recording (ELR) and two-day Holter recording for detecting AF after IS/TIA.Methods191 IS/TIA patients without AF history. Endpoint was AF >30 s. We started two-day Holter recording and seven-day ELR simultaneously.ResultsSeven-day ELR and two-day Holter recording detected the same three AF patients. ELR detected another six patients with AF adjudicated by cardiologists, four detections after Holter (3 vs. 7, p = 0.125) and two false-positive detections during Holter. Seven-day ELR automatically classified 50/191 patients (26%) with AF, but only 7/50 (14%) were confirmed as AF by cardiologists.ConclusionSeven-day ELR did not detect significantly more patients with AF than two-day Holter recording. 86% of patients with ELR-classified AF were false positives, indicating a poor performance of the automatic AF detection algorithm used.

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