Left Atrial Remodeling Parameters and Brain Natriuretic Peptide Levels in Nonvalvular Atrial Fibrillation.

Abstract

Objectives: Left atrium (LA) remodeling, categorized by functional and structural variations, is predominant in heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF). Brain natriuretic peptide (BNP) levels, implying atrial strain, may lead management by indicating LA remodeling severity. This study was instructed to correlate BNP levels with LA volume index (LAVI) in HFpEF patients with nonvalvular AF against sinus rhythm (SR), to evaluate diagnostic implications.

Methods: This two-center, observational, cross-sectional study (April 2023-October 2024) registered 340 patients with de novo HFpEF (140 AF, 200 SR). Patients with left ventricular ejection fraction (LVEF) less than 50 %, valvular disease, or acute conditions were excluded. BNP was measured using enzyme-linked immunosorbent assay and categorized as low (≤200 pg/mL), moderate-high (>200-400 pg/mL), or high (≥400 pg/mL). LAVI was calculated via echocardiography per American Society of Echocardiography (ASE) guidelines, categorized as normal (16-34 mL/m²), mildly abnormal (35-41 mL/m²), moderately abnormal (42-48 mL/m²), or severely abnormal (more than or equal to 49 mL/m²). Spearman correlation, multivariate regression, and subgroup analyses by gender, age, and comorbidities were used to assess the associations.

Results: AF patients had higher BNP (470 ± 280 vs. 400 ± 211 pg/mL, P = 0.013) and LAVI (60.4 ± 19.0 vs. 54.8 ± 22.0 mL/m², P < 0.001). Paradoxically, AF patients with low BNP (≤200 pg/mL) showed higher LAVI (58 ± 22.0 vs. 54 ± 28.9 mL/m², P < 0.001) and worse New York Heart Association (NYHA) class IV symptoms (48.6 % vs. 35.4 % in SR). A negative correlation between BNP and severely abnormal LAVI (≥49 mL/m²) was observed in AF (r = -0.66, P < 0.0001), contrasting with a positive correlation in SR (r = 0.78, P = 0.001). BMI, eGFR, and severely abnormal LAVI were independent predictors (P = 0.004, 0.026, <0.001). Subgroup analyses showed no significant influence of age, gender, or comorbidities.

Conclusion: In HFpEF, low BNP levels in AF patients are paradoxically associated with severe LA remodeling and worse symptoms, unlike in SR. BNP interpretation should integrate clinical, echocardiographic, and strain data, particularly in AF, high BMI, or kidney disease, to optimize management.