Association between natriuretic peptides and left atrial structural and functional properties in atrial fibrillation following catheter ablation

Abstract Background Atrial natriuretic peptides (ANP) and brain natriuretic peptides (BNP) are acutely released from the atrial myocytes upon increased mechanical distension of the atria. The relationship between imaging measures of left atrial (LA) structure and function and natriuretic peptides following catheter ablation (CA) have not been clearly delineated. Purpose To characterize the relationship between LA structure and function and natriuretic peptides. Methods We performed an echocardiographic substudy of a randomized trial of AF patients scheduled for CA. Echocardiographic measurements included: LA volume at end-systole (LAVi), at end-diastole (LAEDVi), emptying fraction (LAEF), LA reservoir strain (LAs), and global longitudinal strain (GLS). Patients were stratified by tertiles of mid-regional proANP (MR-proANP) concentrations in circulation (<92 pmol/l, 92–146 pmol/l, >146 pmol/l), and NT-proBNP (<10pmol/l, 10–38 pmol/l, >38 pmol/l). Linear regressions were performed to compare baseline echocardiographic measures to natriuretic peptide concentrations at baseline, 1 month, 3 months and 6 months of follow-up. MR-proANP and NT-proBNP were logarithm transformed in these analyses. Multivariable adjustments were made for: age, gender, AF subtype, AF burden, rhythm during echocardiogram, rhythm at study visit for blood sampling, time known with AF, beta-blocker use, and CHA-2DS2-VASc score. Results We included 101 patients with AF. The mean age was 58 years, 82% were men, 46% had persistent AF. Increasing tertiles of MR-proANP at baseline were associated with abnormal LA size and function (3rd vs 1st tertile: LAVi: 42mL/m2 vs 32mL/m2; LAEDVi: 31mL/m2 vs 20mL/m2; LAEF: 38% vs 26%; LAs: 27% vs 19%; GLS: −18% vs −14%) whereas both LA and left ventricular measures were associated with increasing NT-proBNP concentrations at baseline. After multivariable adjustments, only LA volumes and LAEF remained significantly associated with MR-proANP, whereas only LA volumes and GLS remained significantly associated with NT-proBNP. At follow-up, impaired LA function associated with persistently elevated concentrations, which was not the case for LAVi (figure). Conclusion MR-proANP reflects LA dysfunction better than NT-proBNP. Measures of LA function rather than LAVi associates with persistently elevated natriuretic peptide concentrationsw, which may indicate that functional measures are more closely associated with evidence of LA myocardial stretch than LAVi. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): The Danish Heart Foundation