PO-01-095 REGIONAL DIFFERENCES IN ATRIAL FIBER STRAINS IN HEART FAILURE PATIENTS WITH AND WITHOUT ATRIAL FIBRILLATION

Abstract

Left atrial (LA) strain is inhibited by atrial fibrosis, which is a hallmark of atrial fibrillation (AF). Retrospective gated computed tomography (CT) imaging with feature tracking (FT) can measure three-dimensional (3D) local LA strain. Atrial myocardial fiber directions may play an important role in preferred deformation, and therefore atrial fiber strains should be considered. Using the average endocardial fiber architecture from seven hearts imaged ex vivo with high resolution diffusion-tensor magnetic resonance imaging (DT-MRI), the endocardial fiber strain can be measured. To investigate regional and global differences in atrial endocardial fiber strains between heart failure (HF) patients with and without AF. 30 HF patients underwent 10-frame gated CT imaging, and FT was used to measure local endocardial fiber strain (Fig. A). The LA body was classified into five regions using Universal Atrial Coordinates (Fig. B). Global and regional strains were reported as the mean strain over the entire LA body surface and within each region, respectively. The fiber strain range over the cardiac cycle was used to stratify between HF patients with and without AF. The left ventricular ejection fraction (LVEF) and left atrial ejection fraction (LAEF) were calculated from the gated CT images. HF patients with AF had smaller global fiber strain ranges than those without AF (5.9 ± 3.7 % vs 14.2 ± 8.9 %, p = 0.011) (Fig. C). All regions had higher strain ranges in HF patients without AF and the anterior wall exhibited the most significant difference between groups (7.8 ± 4.1 vs 17.9 ± 10.6, p = 0.009). ROC analysis using global strain range to stratify between patient groups gave an AUC of 0.853 (Fig. D). The anterior wall was the region with the highest AUC of 0.842. LVEF was similar between patient groups (p=0.682), however LAEF differed (p=0.002) (Fig. E). Patients with AF had decreased fiber strain ranges globally and regionally compared to those without AF. Strain range in the anterior wall most significantly decreased in the presence of AF, which may suggest a regionally higher fibrosis burden. The LVEF was similar between HF patients with and without AF, however the LAEF differed, which suggests strain differences were driven by LA dysfunction.