Aldosterone in local atria, CYP11B2 mRNA expression and atrial structural remodeling in patients with atrial fibrillation

Objective To investigate aldosterone in local atria, the mRNA expression of aldosterone synthase CYP11B2 and atrial structural remodeling in patients with chronic atrial fibrillation, and to find the association of these factors. Methods Twenty-five patients with rheumatic heart valve disease, 12 patients in sinus rhythm and 13 in chronic atrial fibrillation(≥6 months) ,underwent transthoracic echocardiography. Right and left atrial lateral wall tissue samples were obtained simultaneously from these patients during mitral/aortic valve replacement operation. Radioimmunoassay was used to determine aldosterone in local atria and collagen volume fraction (CVF) was analyzed by VG staining. The mRNA expression of aldosterone synthase CYP11B2 in atrial myocardium was determined by using realtime quantitative PCR. Results The left atrial diameters increased markedly in atrial fibrillation group as compared to sinus rhythm group(P 0. 01). Compared with that of sinus rhythm groups, the aldosterone in local atria was increased significantly in atrial fibrillation group(P 0. 001). VG staining revealed that CVF increased significantly in atrial fibrillation groups compared with that in sinus rhythm group( P 0. 001). And the level of mRNA of CYP11B2 was increased greatly in atrial fibrillation groups compared with that in sinus rhythm(P 0. 001). But the aldosterone, CVF and the mRNA expression of CYP11B2 were found to be no difference between left atria and right atria both in fibrillation and sinus groups (all P 0. 05). CVF significantly correlated with left atrial dimension ( r = 0. 845 ,P 0. 001). And aldoste- rone was found to be significantly positive correlated with left atrial dimension (r=0. 814, P 0. 001) and CVF ( r = 0. 885 , P 0. 001). There was also a positive correlation between the mRNA level of CYP11B2 and CVF (R =0. 757, P 0. 001). Conclusions Atrial structural remodeling during atrial fibrillation is manifested by increased aldosterone level in local atria along with upregulation of the mRNA of CYP11B2. These findings suggest that aldosterone antagonists may be effective in arresting atrial structural remodeling and the development of sustained atrial fibrillation.