Left atrial sphericity in relation to atrial strain and strain rate in atrial fibrillation patients

Purpose Left atrial (LA) sphericity is a novel, geometry-based parameter that has been used to visualize and quantify LA geometrical remodeling in patients with atrial fibrillation (AF). This study examined the association between LA sphericity, and LA longitudinal strain and strain rate measured by feature-tracking in AF patients. Methods 128 AF patients who underwent cardiovascular magnetic resonance (CMR) imaging in sinus rhythm prior to their pulmonary vein isolation (PVI) procedure were retrospectively analyzed. LA sphericity was calculated by segmenting the LA (excluding the pulmonary veins and the LA appendage) on a 3D contrast enhanced MR angiogram and comparing the resulting shape with a perfect sphere. LA global reservoir strain, conduit strain, contractile strain and corresponding strain rates were derived from cine images using feature-tracking. For statistical analysis, Pearson correlations, multivariable logistic regression analysis, and Student t -tests were used. Results Patients with a spherical LA (dichotomized by the median value) had a lower reservoir strain and conduit strain compared to patients with a non-spherical LA (-15.4 ± 4.2% vs. -17.1 ± 3.5%, P = 0.02 and − 8.2 ± 3.0% vs. -9.5 ± 2.6%, P = 0.01, respectively). LA strain rate during early ventricular diastole was also different between both groups (-0.7 ± 0.3s − 1 vs. -0.9 ± 0.3s − 1 , P = 0.001). In contrast, no difference was found for LA contractile strain (-7.2 ± 2.6% vs. -7.6 ± 2.2%, P = 0.30). Conclusions LA passive strain is significantly impaired in AF patients with a spherical LA, though this relation was not independent from LA volume. Key points This study found that LA passive function, measured using strain assessment, is significantly impaired in AF patients with a spherical LA as compared to patients with a non-spherical LA. The relation between LA sphericity and LA strain was not independent from LA volume. In patients with a spherical LA, an increase in LA pressure is related to a deterioration in LA function, while in patients with a normal non-sphere shaped LA, LA function remains largely preserved.