Electrocardiographic markers of subclinical atrial fibrillation detected by implantable loop recorder: insights from the LOOP Study

Lucas Yixi Xing, Søren Zöga Diederichsen, Søren Højberg, Derk W Krieger, Claus Graff, Morten S Olesen, Jonas Bille Nielsen, Axel Brandes, Lars Køber, Ketil Jørgen Haugan, Jesper Hastrup Svendsen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Aims Insights into subclinical atrial fibrillation (AF) development are warranted to inform the strategies of screening and subsequent clinical management upon AF detection. Hence, this study sought to characterize the onset and progression of subclinical AF with respect to 12-lead electrocardiogram (ECG) parameters. Methods We included AF-naïve individuals aged 70–90 years with additional stroke risk factors who underwent implantable loop re- and results corder (ILR) monitoring in the LOOP Study. Using data from daily ILR recordings and the computerized analysis of baseline ECG, we studied empirically selected ECG parameters for AF detection (≥6 min), cumulative AF burden, long-lasting AF (≥24 h), and AF progression. Of 1370 individuals included, 419 (30.6%) developed AF during follow-up, with a mean cumulative AF burden of 1.5% [95% CI: 1.2–1.8]. Several P-wave-related and ventricular ECG parameters were associated with new-onset AF and with cumulative AF burden in AF patients. P-wave duration (PWD), P-wave terminal force in Lead V 1, and interatrial block (IAB) further demonstrated significant associations with long-lasting AF. Among AF patients, we observed an overall reduction in cumulative AF burden over time (IRR 0.70 [95% CI: 0.51–0.96]), whereas IAB was related to an increased risk of progression to AF ≥24 h (HR 1.86 [95% CI: 1.02–3.39]). Further spline analysis also revealed longer PWD to be associated with this progression in AF duration. Conclusion We identified several ECG parameters associated with new-onset subclinical AF detected by ILR. Especially PWD and IAB were robustly related to the onset and the burden of AF as well as progression over time.

Original languageEnglish
Article numbereuad014
JournalEP - Europace
Issue number5
Number of pages10
Publication statusPublished - 19. May 2023


  • Atrial fibrillation
  • Cardiac arrhythmias
  • Electrocardiography
  • P-wave
  • Stroke
  • Interatrial Block
  • Humans
  • Risk Factors
  • Electrodes, Implanted/adverse effects
  • Electrocardiography/methods
  • Stroke/prevention & control
  • Atrial Fibrillation/diagnosis
  • Electrocardiography, Ambulatory


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