P-wave signal-averaged ECG as a marker of left atrial electrical and structural remodeling in patients with atrial fibrillation

Background Atrial fibrillation (AF) is closely associated with structural and electrical remodeling of the left atrium (LA). Early detection of subtle LA changes is crucial for timely intervention and halting disease progression. P-wave signal-averaged ECG (P-SAECG) offers advanced analysis of atrial electrical conduction by measuring parameters, which may reflect underlying remodeling. However, P-SAECG remains underused, and cutoff values have not been established. Purpose The aim of this study was to investigate associations between SAECG-derived atrial electrocardiographic markers and echocardiographic measures of LA size, structure, and function in AF patients. Methods In this prospective single-center study, patients with AF who were in sinus rhythm at presentation underwent P-SAECG using a system with orthogonal X, Y, and Z leads following a standardized protocol. A minimum of 200 beats were signal-averaged to assess unfiltered and filtered P-wave durations (ms), root mean square (RMS) voltages in the terminal 20, 30, and 40 ms (μV), overall P-wave RMS, and P-wave integral (μV-ms). Recordings with noise >0.6 μV were excluded. Transthoracic echocardiography included left ventricular ejection fraction (LVEF) by Simpson’s biplane method, LA diameter, LA volume index (LAVi) by the area-length method, LA ejection fraction (LAEF), and LA reservoir strain (LASr) by 2D speckle-tracking. The LA stiffness index (LASi) was calculated as (E/e′)/LASr. LA sphericity index was defined as the ratio of maximal horizontal to vertical LA diameters in the apical four-chamber view. Results Forty patients were included (31% female, mean age 62.3 ± 10.5 years, 66.7% with paroxysmal AF, mean AF duration 5.29 ± 6.82 years, mean LVEF 57.7 ± 3.8%, mean LA diameter 39.9 ± 4.2 mm). P-wave filtered duration correlated with LA diameter (p = 0.018), indicating a relationship between atrial conduction delay and anatomical enlargement. P-wave integral showed significant associations with LA sphericity index (p = 0.02) and LAVi (p = 0.02). RMS20 demonstrated a borderline association with LA reservoir strain (p = 0.08). In multivariate analysis, only the association between P-wave integral and LA sphericity index remained significant, suggesting that overall atrial activation energy may reflect early geometric remodeling independent of chamber volume. No significant associations were observed between SAECG parameters and LAEF or LASi. Conclusion Among SAECG markers, P-wave filtered duration is correlated with LA diameter, while P-wave integral is independently associated with LA sphericity index, highlighting its potential as a marker of early geometric remodeling. These findings suggest that combining P-SAECG with echocardiography may enhance non-invasive evaluation of atrial remodeling in AF. Further studies with larger cohorts are needed to validate these results and explore their prognostic value in risk stratification and personalized AF management.