Assessment of Left Atrial Fibrosis by Late Gadolinium Enhancement Magnetic Resonance Imaging

Abstract

Recently, studies using late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) to identify structural changes of atrial tissue have contributed significantly to understanding the pathophysiology and progression of atrial fibrillation (AF). Moreover, imaging of atrial fibrosis using MRI has evolved to be a tool to improve clinical outcome of AF ablation procedures by allowing a patient-specific individualized management approach. LGE-MRI has been shown to predict AF ablation outcome based on pre-procedural imaging to define the extent of atrial fibrosis. The results of the ongoing DECAAF II (Delayed-Enhancement MRI Determinant of Successful Radiofrequency Catheter Ablation of Atrial Fibrillation) trial might extend ablation strategies from pulmonary vein isolation alone to a substrate-based approach. Furthermore, an improved understanding of the underlying mechanisms of atrial structural remodeling is crucial in order to reduce the occurrence of AF-associated complications (e.g., ischemic stroke and heart failure). This review article provides current methodology of atrial fibrosis imaging using LGE-MRI and delineates actual clinical implications and future directions for this imaging approach.

Loss-of-Function Variants in Cytoskeletal Genes Are Associated with Early-Onset Atrial Fibrillation

“…It was, therefore, discussed whether ablative therapy is beneficial when AF occurs as a result of atrial cardiomyopathy [37]. Ongoing studies are evaluating whether detection of fibrosis before ablation, using late gadolinium enhancement magnetic resonance, may improve the ablation of AF in fibrotic hearts [38]. Several of the genes examined in this study are linked with cardiac fibrosis.…”

Left Atrial Structural Remodelling in Non-Valvular Atrial Fibrillation: What Have We Learnt from CMR?

“…The high-resolution LA images are initially acquired 15-30 min after gadolinium-based contrast agent administration by delivering an ECG gated and respiratory-navigated (3D inversion-recovery gradient echo pulse. ECG gating implies synchronizing image acquisition to a certain cardiac cycle phase (atrial diastole), with the purpose of minimizing motion artefacts and maximizing the image acquisition window [25]. When assessing atrial fibrosis, image acquisition is preferably done at the end of the expiration and in atrial diastole.…”

“…An operator manually defines the LA endocardial border, while excluding the mitral valve and left ventricle in order to define the LA segments. The heterogeneous image intensities are corrected before assessing fibrosis by using the blood pool as a comparator [25,26]. The software automatically/semi-automatically defines fibrotic versus non-fibrotic myocardium by detecting the subsequent difference in pixel intensity thresholds (normally, 2 to 4 SD).…”

Reproducibility and accuracy of late gadolinium enhancement cardiac magnetic resonance measurements for the detection of left atrial fibrosis in patients undergoing atrial fibrillation ablation procedures

“…Few studies have assessed the reproducibility of LGE-CMR detected LA fibrosis, and none specifically addressed the impact of observer's experience on reproducibility, nor did they assessed the accuracy of scar overlap or geometric congruency of the reconstructed 3D shell (10). Also, most of studies used the Corview software package and the DECAFF protocol to detect and quantify LA fibrosis (10).…”