Relationship between local production of microRNA-328 and atrial substrate remodeling in atrial fibrillation

Background: The underlying mechanism of atrial substrate remodeling in atrial fibrillation (AF) remains unknown. In this study, we investigated whether local and systemic levels of microRNA (miR) might be associated with the presence of AF and with left atrial (LA) substrate properties. Methods: Blood from the periphery, pulmonary vein (PV), and left atrial appendage (LAA) was sampled from 30 patients with AF undergoing PV isolation, and from 10 control subjects with Wolff-Parkinson White syndrome and without AF. We measured peripheral, PV, and LAA plasma levels of miR-1,-26, -133a, -328, and -590 by reverse transcription-polymerase chain reaction. LA global contact mapping during sinus rhythm was performed before PV isolation. Results: Plasma levels of miR-328 were higher in patients with AF than in control subjects. Plasma miR-328 levels were significantly higher in the LAA than in the periphery and PV in patients with AF, but not in control subjects. Plasma miR-1 levels were also higher in the LAA than in the PV in AF patients. Interestingly, LAA plasma levels of miR-328 showed a positive correlation with the LA voltage zone index (area with voltage <0.5 mV divided by total LA surface area) and a weak correlation with LA volume. Conclusion: Local production of miR-328 in the left atrium may be involved in the process of atrial remodeling in patients with AF. (C) 2016 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.