Abstract
Background/Introduction
Left atrial (LA) sphericity has been proposed as a more sensitive marker of atrial fibrillation (AF)-associated atrial remodeling compared to traditional markers such as LA size. However, mechanisms that underlie changes in LA sphericity are not fully understood and studies investigating the predictive value of LA sphericity for AF ablation outcome have yielded conflicting results.
Purpose
The present study aimed to assess correlates of LA sphericity and to compare LA sphericity in subjects with and without AF.
Methods
Measures of LA size (LA diameter, LA volume, LA volume index), LA sphericity and thoracic anteroposterior diameter (APd) at the level of the LA were determined in a total of 293 AF patients (62% paroxysmal AF) and 110 controls. Cardiac computed tomography (CT) images were analyzed offline by a reviewer blinded to clinical parameters. The AF cohort consisted of consecutive patients referred for cardiac CT imaging prior to first AF ablation procedure between January 2015 and January 2018. The control cohort consisted of subjects with no history of AF who underwent cardiac CT imaging between January 2012 and October 2014 to exclude coronary artery disease.
Results
LA diameter (40.1 ± 6.8 mm vs. 35.2 ± 5.1 mm; p < 0.001), LA volume (116.0 ± 33.0 ml vs. 80.3 ± 22.6 ml; p < 0.001) and LA volume index (56.1 ± 15.3 ml/m² vs. 41.6 ± 11.1 ml/m²; p < 0.001) were significantly larger in AF patients compared to controls (Figure), also after adjustment for age and sex. LA sphericity did not differ between AF patients and controls (83.7 ± 2.9 vs. 83.9 ± 2.4; p = 0.642). A moderate correlation was noted between thoracic APd and LA sphericity in both females (R = 0.521, p < 0.001) and males (R = 0.498, p < 0.001). Multivariable linear regression analysis demonstrated that LA diameter, LA volume, female sex, body length and thoracic APd were independently associated with LA sphericity.
Conclusion
The present study suggests that thoracic constraints rather than the presence of AF determine LA sphericity, implying LA sphericity to be unsuitable as a marker of AF-related atrial remodeling.
Abstract Figure. Comparison of LA imaging characteristics
Electrical isolation of pulmonary veins in patients with atrial fibrillation: reduction of fluoroscopy exposure and procedure duration by the use of a non-fluoroscopic navigation system (NavX®)