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Prognostic value of ECG-derived f-wave indices from implantable loop recorder : Analysis from the LOOP study

Plappert, Felix LU orcid ; Diederichsen, Søren Zöga ; Graff, Claus ; Xing, Lucas Yixi ; Haugan, Ketil Jørgen ; Højberg, Søren ; Krieger, Derk W. ; Brandes, Axel ; Køber, Lars and Biering-Sørensen, Tor , et al. (2026) In Heart Rhythm
Abstract

BACKGROUND: Electrocardiogram (ECG)-derived indices of atrial remodeling have demonstrated predictive value in established atrial fibrillation (AF) but remain unexplored in screening-detected or symptomatic AF.

OBJECTIVE: We investigated the prognostic value of implantable loop recorders (ILR) ECG-derived atrial fibrillatory rate (AFR), average f-wave envelope amplitude (FWA), and the organization index derived from the signal's spectral characteristics (ExpDec).

METHODS: We analyzed 1411 LOOP study participants (758 men, median age 73 years) with ILR and no prior AF. Baseline AFR, ExpDec, and FWA indices were extracted from AF episodes ≥60 minutes occurring within 1 year after ILR implantation. Multivariate Cox regression... (More)

BACKGROUND: Electrocardiogram (ECG)-derived indices of atrial remodeling have demonstrated predictive value in established atrial fibrillation (AF) but remain unexplored in screening-detected or symptomatic AF.

OBJECTIVE: We investigated the prognostic value of implantable loop recorders (ILR) ECG-derived atrial fibrillatory rate (AFR), average f-wave envelope amplitude (FWA), and the organization index derived from the signal's spectral characteristics (ExpDec).

METHODS: We analyzed 1411 LOOP study participants (758 men, median age 73 years) with ILR and no prior AF. Baseline AFR, ExpDec, and FWA indices were extracted from AF episodes ≥60 minutes occurring within 1 year after ILR implantation. Multivariate Cox regression assessed associations with all-cause mortality (primary end point) and a composite end point of cardiovascular death (CVD) or heart failure hospitalization (secondary end point).

RESULTS: During the first year of monitoring, AF episodes ≥60 minutes were detected in 96 patients (6.8%). Low AFR (<317 fpm), ExpDec (<1.25), and FWA (<97 μV) were associated with increased risk of all-cause mortality (hazard ratio [HR] 95% confidence interval [CI]: 2.5 [1.3-4.8], 2.8 [1.4-5.5], and 2.7 [1.4-5.4], respectively) and similarly for the composite end point of CVD or heart failure hospitalization, although with larger uncertainty (HR [95% CI]: 4.0 [1.6-9.9], 3.7 [1.4-10.1], 2.9 [0.97-8.6], respectively). FWA demonstrated a significant, yet modest, negative correlation with left atrial volume.

CONCLUSION: In screening-detected AF, indices of a more organized fibrillatory process (low AFR/ExpDec) and advanced structural abnormalities (low FWA) were associated with increased mortality and heart failure events. F-wave analysis identifies high-risk patients in early AF, potentially enabling targeted interventions.

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publication status
epub
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Heart Rhythm
publisher
Elsevier
external identifiers
  • pmid:42442589
ISSN
1547-5271
DOI
10.1016/j.hrthm.2026.07.005
language
English
LU publication?
yes
additional info
Copyright © 2026 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.
id
8d14c0be-f5d2-4cba-9b2c-1a22e7e1ff4e
date added to LUP
2026-08-21 13:40:31
date last changed
2026-08-25 11:49:48
@article{8d14c0be-f5d2-4cba-9b2c-1a22e7e1ff4e,
  abstract     = {{<p>BACKGROUND: Electrocardiogram (ECG)-derived indices of atrial remodeling have demonstrated predictive value in established atrial fibrillation (AF) but remain unexplored in screening-detected or symptomatic AF.</p><p>OBJECTIVE: We investigated the prognostic value of implantable loop recorders (ILR) ECG-derived atrial fibrillatory rate (AFR), average f-wave envelope amplitude (FWA), and the organization index derived from the signal's spectral characteristics (ExpDec).</p><p>METHODS: We analyzed 1411 LOOP study participants (758 men, median age 73 years) with ILR and no prior AF. Baseline AFR, ExpDec, and FWA indices were extracted from AF episodes ≥60 minutes occurring within 1 year after ILR implantation. Multivariate Cox regression assessed associations with all-cause mortality (primary end point) and a composite end point of cardiovascular death (CVD) or heart failure hospitalization (secondary end point).</p><p>RESULTS: During the first year of monitoring, AF episodes ≥60 minutes were detected in 96 patients (6.8%). Low AFR (&lt;317 fpm), ExpDec (&lt;1.25), and FWA (&lt;97 μV) were associated with increased risk of all-cause mortality (hazard ratio [HR] 95% confidence interval [CI]: 2.5 [1.3-4.8], 2.8 [1.4-5.5], and 2.7 [1.4-5.4], respectively) and similarly for the composite end point of CVD or heart failure hospitalization, although with larger uncertainty (HR [95% CI]: 4.0 [1.6-9.9], 3.7 [1.4-10.1], 2.9 [0.97-8.6], respectively). FWA demonstrated a significant, yet modest, negative correlation with left atrial volume.</p><p>CONCLUSION: In screening-detected AF, indices of a more organized fibrillatory process (low AFR/ExpDec) and advanced structural abnormalities (low FWA) were associated with increased mortality and heart failure events. F-wave analysis identifies high-risk patients in early AF, potentially enabling targeted interventions.</p>}},
  author       = {{Plappert, Felix and Diederichsen, Søren Zöga and Graff, Claus and Xing, Lucas Yixi and Haugan, Ketil Jørgen and Højberg, Søren and Krieger, Derk W. and Brandes, Axel and Køber, Lars and Biering-Sørensen, Tor and Olsen, Flemming Javier and Holmqvist, Fredrik and Wallman, Mikael and Sandberg, Frida and Svendsen, Jesper Hastrup and Platonov, Pyotr G}},
  issn         = {{1547-5271}},
  language     = {{eng}},
  month        = {{07}},
  publisher    = {{Elsevier}},
  series       = {{Heart Rhythm}},
  title        = {{Prognostic value of ECG-derived f-wave indices from implantable loop recorder : Analysis from the LOOP study}},
  url          = {{http://dx.doi.org/10.1016/j.hrthm.2026.07.005}},
  doi          = {{10.1016/j.hrthm.2026.07.005}},
  year         = {{2026}},
}