Extent of Left Atrial Fibrosis Correlates with Descending Aorta Proximity at 3D Late Gadolinium Enhancement Cardiac MRI in Patients with Atrial Fibrillation.

Purpose: To determine whether the distance between the descending aorta and left atrial (LA) wall correlates with the amount of fibrosis quantified in the posterior left inferior pulmonary vein (LIPV) area of the LA in patients with atrial fibrillation (AF). Materials and
Methods: In this retrospective study, patients with AF underwent cardiac MRI in sinus rhythm prior to a pulmonary vein isolation procedure (July 2018 to February 2020). The mean distance (distancemean) and shortest distance (distanceshort) between the descending aorta and the LA wall were measured on three-dimensional (3D) contrast-enhanced MR angiograms; distancemean was defined as the average of five measurements at different levels between the descending aorta and the LA wall. The extent of LA fibrosis, both global fibrosis and regional fibrosis within the LIPV area, was derived from postprocessed, 3D, late gadolinium-enhanced images. Associations between the extent of fibrosis and the proximity of the descending aorta were analyzed by using correlative and multivariable analyses.
Results: A total of 47 (mean age, 60 years ± 8 [standard deviation]; 31 men) patients were included for analysis. The extent of fibrosis in the posterior LIPV area was correlated with the distancemean (r s = -0.48; P < .01) and distanceshort (r s = -0.49; P < .01). Patients with a short distance between the descending aorta and LA wall (defined as a distanceshort < 2 mm) had a higher percentage of fibrosis in the posterior LIPV area than patients with a distanceshort greater than 2 mm (38.7% ± 22.7 vs 21.2% ± 17.8; P < .01).
Conclusion: The distance between the descending aorta and LA was correlated with the extent of quantified fibrosis within the posterior LIPV area.Keywords: MRI, Cardiac, Left Atrium Supplemental material is available for this article. © RSNA, 2022. 2022 by the Radiological Society of North America, Inc.