Accuracy of Late Gadolinium Enhancement - Magnetic Resonance Imaging in the Measurement of Left Atrial Substrate Remodeling in Patients With Rheumatic Mitral Valve Disease and Persistent Atrial Fibrillation.

Abstract

The aim of this study was to provide a histopathological validation of cardiac late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) for the assessment of left atrial (LA) substrate remodeling (SRM) in patients with rheumatic mitral valve disease and persistent atrial fibrillation (AF).Adult patients with rheumatic mitral valve disease and persistent AF undergoing open-heart surgery for mitral valve replacement were enrolled. Both two-dimensional (2D) sections and 3-dimensional (3D) full-volume LGE-MRI with different signal intensities were performed preoperatively to determine the extent of LA-SRM. Tissue samples were obtained intraoperatively from the LA roof and posterior lateral wall for pathological validation with Masson trichrome staining and immunostaining for collagen type I/III deposition. A linear regression model was used to determine the relationship between MRI-derived LA-SRM parameters and pathological results.Between February 2013 and March 2014, we successfully acquired LA tissue samples from 22 patients (13 men), with a mean age of 47 ± 8 years. All patients had rheumatic mitral valve stenosis, with a mean effective orifice area of 0.9 ± 0.2 cm(2) on echocardiography and a mean LA volume of 235 ± 85 mL on 3D-MRI. Multiple moderate linear associations were noted between the pathological results and LGE-MRI-derived LA-SRM parameters, with correlation indices (r(2)) of 0.194-0.385.LA-SRM measured by LGE-MRI showed moderate agreement with LA pathology in patients with rheumatic valve disease and persistent AF.