Standardised computed tomographic assessment of left atrial morphology and tissue thickness in humans

Abstract

Aims: Left atrial (LA) remodelling is a common feature of many cardiovascular pathologies and is a sensitive marker of adverse cardiovascular outcomes. The aim of this study was to establish normal ranges for LA parameters derived from coronary computed tomographic angiography (CCTA) imaging using a standardised image processing pipeline to establish normal ranges in a previously described cohort.

Methods: CCTA imaging from 193 subjects recruited to the Budapest GLOBAL twin study was analysed. Indexed LA cavity volume (LACV_i), LA surface area (LASA_i), wall thickness and LA tissue volume (LATV_i) were calculated. Wall thickness maps were combined into an atlas. Indexed LA parameters were compared with clinical variables to identify early markers of pathological remodelling.

Results: LACV_i is similar between sexes (31 ml/m² v 30 ml/m²) and increased in hypertension (33 ml/m² v 29 ml/m², p = 0.009). LASA_i is greater in females than males (47.8 ml/m² v 45.8 ml/m² male, p = 0.031). Median LAWT was 1.45 mm. LAWT was lowest at the inferior portion of the posterior LA wall (1.14 mm) and greatest in the septum (median = 2.0 mm) (p < 0.001). Conditions known to predispose to the development of AF were not associated with differences in tissue thickness.

Conclusions: The reported LACV_i, LASA_i, LATV_i and tissue thickness derived from CCTA may serve as reference values for this age group and clinical characteristics for future studies. Increased LASA_i in females in the absence of differences in LACV_i or LATV_i may indicate differential LA shape changes between the sexes. AF predisposing conditions, other than sex, were not associated with detectable changes in LAWT.Clinical trial registration:http://www.ClinicalTrials.gov/NCT01738828.

Keywords: AF, atrial fibrillation; BSA, body surface area; CCTA, cardiac computed tomography; Computed tomography (CT); DZ, dizygotic; LA, left atrium; LAA, left atrial appendage; LACV, left atrial cavity volume; LASA, left atrial surface area; LATV, left atrial tissue volume; LAWT, left atrial wall thickness; Left atrium; MZ, monozygotic; PV, pulmonary vein; Tissue thickness.