Cardiac MR Strain: A Noninvasive Biomarker of Fibrofatty Remodeling of the Left Atrial Myocardium

Abstract

Purpose To determine whether left atrial (LA) strain quantification with cardiac magnetic resonance (MR) imaging feature tracking is associated with the severity of LA fibrofatty myocardial remodeling at histologic analysis. Materials and Methods This prospective case-control study was approved by the institutional review board. LA strain was evaluated with cardiac MR feature tracking between January 2014 and March 2015 in 13 consecutive patients (mean age, 61 years ± 19; nine male) with mitral regurgitation in the 24 hours before mitral valve surgery and 13 age- and sex-matched healthy control subjects. LA strain parameters were compared first between control subjects and patients and then according to atrial fibrillation and mitral regurgitation status. Associations between LA strain and histology of preoperative biopsies were reported by using receiver operating characteristic curve analysis and Spearman correlation. Results Peak longitudinal atrial strain (PLAS) was significantly lower in patients with mitral regurgitation than in healthy control subjects (P < .001). Increased LA remodeling was significantly related to altered LA strain, and the strongest association was found between PLAS and the degree of fibrofatty myocardial replacement at histologic analysis (r = -0.75, P = .017). LA end-diastolic volume was increased in patients with mitral regurgitation when compared with that in healthy volunteers (P < .001) because of volume overload; however, volume did not correlate with the histologic degree of LA fibrofatty replacement (r = -0.35, P = .330). Conclusion LA strain, especially PLAS, correlates strongly with the degree of fibrofatty replacement at histologic analysis. Such functional imaging biomarker in combination with LA volumetry could help to guide clinical decisions, since myocardial structural remodeling is a known morphologic substrate of LA dysfunction leading to atrial fibrillation with adverse outcome. RSNA, 2017 Online supplemental material is available for this article.

The Differential Meaning of LV and LA Strains in Aortic Valve Stenosis: A Feature Tracking MRI Study

“…Associations of LA function with LV remodeling and LV longitudinal strain revealed that: 1) LA reservoir function seems to be a mixture of LA compliance impairment due to fibro-fatty infiltration in the LA myocardium as well as of LV longitudinal dysfunction. Indeed in the present study LA reservoir function seems to be related to LV longitudinal strain while it has been significantly associated to histological LA tissue characteristics in a previous study [12], 2) LA conduit phase might be mainly LV driven, 3) LA contraction phase strain indices were not linearly associated to LV remodeling but rather in a bi-phasic behavior indicating its ability to reflect the compensatory role of the LA to LV early filling but also the loss in LA myocardium contractility. Accordingly, while LA reservoir and conduit strains can be regarded as partially LV-driven indices, LA contraction strain can be regarded as an intrinsic LA function index.…”

Epicardial Adipose Tissue Is Associated With Left Atrial Dysfunction in People Without Obstructive Coronary Artery Disease or Atrial Fibrillation

“…17 Additionally, LA strain, evaluated by cardiac magnetic resonance image, was shown a strong degree correlation with fibrofatty replacement at a histological level. 18 In our present study, larger EATi volume was closely associated with more impaired LA global longitudinal strain, regardless of confounding factors. EATi volume negatively correlated with 3D-LAEF and 3D-active LAEF.…”

Strain maps of the left atrium imaged with a novel high-resolution CINE MRI protocol

“…Although dynamic magnetic resonance imaging (CINE MRI) has also been used to estimate global atrial function, these analyses have traditionally been based on one or two 8 to 10-mm thick 2D slices [9], [10]. This poor spatial coverage and resolution precludes an analysis of regional atrial strains, which are likely to be of important clinical value.…”