Mineralocorticoid receptor, CYP11B2 mRNA expression, and atrial matrix remodelling in patients with atrial fibrillation

OBJECTIVE: Atrial fibrillation is associated with the activation of the renin-angiotensin-aldosterone system in the atria. It is not clear whether the expression of mineralocorticoid receptor (MR) and aldosterone synthase CYPII B2 in patients with atrial fibrillation is altered. This study aimed to investigate the mRNA expression of MR and CYPIIB2 and to reveal the correlation between CYPIIB2 mRNA and matrix remodelling in patients with atrial fibrillation. METHODS: Twenty-five patients with rheumatic heart valve disease, 12 in sinus rhythm and 13 in atrial fibrillation (> or = 6 months), underwent a valve replacement operation and right and left atrial lateral wall tissue samples were obtained. The MR and CYPI IB2 expressions were analysed at the mRNA level and collagen volume fraction was determined by Van Gieson's staining. Results - Collagen volume fraction was found to be increased significantly in atrial fibrillation groups compared with sinus rhythm groups (P < 0.001). Both the mRNA of MR and CYPIIB2 were significantly increased in the fibrillation group compared with the group in sinus rhythm (P < 0.01). Collagen volume fraction significantly and positively correlated with left atrial dimension (r = 0.845, P < 0.001).There was a positive correlation between CYPI I B2 mRNA and collagen volume fraction (r = 0.757, P < 0.001). CONCLUSION: Increased expression of MR and CYPIIB2 in the atria is one of the molecular mechanisms for the development of atrial interstitial fibrosis in patients with atrial fibrillation.