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

Area of Science:

• Cardiology
• Biomedical Engineering
• Electrocardiography

Background:

• Atrial remodeling indices from ECG predict outcomes in established atrial fibrillation (AF).
• These indices are unexplored in screening-detected or symptomatic AF.
• Implantable loop recorders (ILR) allow continuous monitoring for early AF detection.

Purpose of the Study:

• To investigate the prognostic value of ILR-derived ECG indices in patients without prior AF.
• Specifically examined atrial fibrillatory rate (AFR), average f-wave envelope amplitude (FWA), and organization index (ExpDec).
• Assessed associations with all-cause mortality and a composite of cardiovascular death or heart failure hospitalization.

Main Methods:

• Analysis of 1,411 LOOP study participants with ILRs, median age 73.
• Extracted baseline AFR, ExpDec, and FWA from AF episodes ≥60 minutes within one year.
• Multivariate Cox regression used to assess outcomes.

Main Results:

• AF episodes ≥60 minutes detected in 6.8% of participants within the first year.
• Low AFR (<317 fpm), ExpDec (<1.25), and FWA (<97 μV) were associated with increased all-cause mortality.
• Similar associations observed for cardiovascular death or heart failure hospitalization, with FWA correlating with left atrial volume.

Conclusions:

• In screening-detected AF, a more organized fibrillatory process (low AFR/ExpDec) and structural abnormalities (low FWA) predict mortality and heart failure events.
• F-wave analysis identifies high-risk patients in early AF.
• These findings may enable targeted interventions for improved patient outcomes.