Valvular heart disease and atrial fibrillation regulate microRNA expression profiles in left and right atria differently

Background: Chronic atrial fibrillation (AF) is a complication associated with the dilated atria of patients with valvular heart disease and contributes to worsened pathology. Methods and Results: Using microarray technology, we examined microRNA (miR) expression profiles in right and left atrial appendage tissue from valvular heart disease (VHD) patients. Right atrial appendage from patients undergoing coronary artery bypass grafting (CABG) and left atrial (LA) appendage from healthy hearts not used for transplant were used as controls. VHD induced different changes in miR expression in LA compared with right atria (RA). Fifty-two (52) miRs were altered by VHD in LA, compared with 5 in RA tissue. There was no detectable effect of chronic AF on miR expression in LA tissue, but miR expression in RA was strongly influenced by AF, with 47 miRs showing differential expression. LA volume correlated with miR expression changes in both LA and RA, but the affected miRs were different for the two atrial groups. Conclusions: VHD and AF influence miR expression patterns in LA and RA, but these are affected differently by disease progression and by the development of AF. These findings provide new insights into the progression of VHD. RA tissue is not a useful surrogate for LA in studies of mitral valve disease. 34 arrays from either the left or right atrium from patients with Valvular Heart Disease (VHD), patients undergoing coronary artery bypass grafting (CABG), or healthy controls. Arrays in this series were generated on V2 and V3 Agilent microRNA arrays and analysed in combination.