Atrial tissue aldosterone level and atrial extracellular matrix remodeling in patients with atrial fibrillation

AIM To investigate atrial tissue aldosterone level and atrial extracellular matrix remodeling in patients with atrial fibrillation and to evaluate the effects of aldosterone on the progress of atrial structural remodeling. METHODS Twenty-five patients with rheumatic heart valve disease, 12 in sinus rhythm and 13 in chronic atrial fibrillation (≥6 months), underwent transthoracic echocardiography and right and left atrial lateral wall tissue samples were obtained from these patients during mitral/aortic valve replacement operation. Radioimmunoassay was used to determine tissue aldosterone level in local atria. The mRNA expression of Type Ⅰor Ⅲ collagen and total collagen volume fraction (CVF) were analyzed by RT-PCR and VG staining respectively. RESULTS The left atrial diameters increased markedly in the atrial fibrillation as compared to sinus rhythm (P<0.01). The results suggested that atrial tissue aldosterone level \(310.3±69.6) vs (154.5±35.8) pg/g in right atria, (334.2±76.6) vs (166.5±38.6) pg/g in left atria, both P<0.01\, the mRNA expression of TypeⅠcollagen \(1.95±0.22) vs (0.71±0.11) in right atria, (2.05±0.28) vs (0.74±0.16) in left atria, both P<0.01) and total CVF \(13.0±1.9)％ vs (6.5±1.1)％ in right left, (14.1±1.7)％ vs (6.7±1.2)％ in left atria, both P<0.01) all increased significantly in atrial fibrillation groups compared with those in sinus rhythm, whereas the mRNA expression of type Ⅲ collagen remained compatible within groups. No significant difference was found in aldosterone, the mRNA expression of typeⅠcollagen and total CVF between left atria and right atria both in fibrillation and sinus groups. There were significant positive correlation between typeⅠ collagen mRNA expression and left atrial dimension, CVF and left atrial dimension, and the correlation coefficient r was 0.885 and 0.845 respectively (both P<0.01). Tissue aldosterone in local atria also significantly was correlated with left atrial dimension（r＝0.814， P<0.01） and CVF（r＝0.885， P<0.01）. CONCLUSION Aldosterone in local atria may promote the process of atrial matrix remodeling and probably participate in the mediation and persistence of atrial fibrillation.