Normal indexed values of left atrial volume by age and gender in a population of 250 healthy subjects: a CT-study

Left atrial volume (LAV) is predictive of cardiovascular outcomes. Its reference values have been described with 2D-transthoracic echocardiography (TTE) and cardiac MRI but very few data are published regarding cardiac computed tomography angiography (CCTA) values. Recent guidelines have highlighted the role of CT-scan, which is a valuable tool to evaluate cardiac dimensions, by its volumetric approach, with a minimal time acquisition and high reproducibility.

We aimed to provide CCTA normal LAV reference values by age and gender in a population of 250 healthy subjects.

We retrospectively included 250 adults (18–74 years) who underwent a retrospectively ECG-gated CCTA in our institution, in order to rule out coronary disease after an episode of chest pain, without any history of cardiac disease or anomaly on the CT-scan. We divided our population in 5 classes of age (<40; 40–49; 50–59; 60–69; ≥70 years) with 1:1 sex ratio. LAV was evaluated at 40% of RR cycle, corresponding to maximal volume, by 2 different methods: semi-automated volumetric approach (3D) and manual area-length (A-L), as recommended for echocardiography and MRI.

In the overall population, mean LAV was 50.6±12.7 ml/m² (lower and upper limits 25 and 76 ml/m² respectively) by 3D method and slightly lower using A-L method (42.8±11.5 ml/m²) (LL and UL 20 and 66 ml/m² respectively). Normal values were 22–81 ml/m² (3D) and 17–68 ml/m² (A-L) in men and 30–70 ml/m² (3D) and 23–63 ml/m² (A-L) in women. There was no significant difference across genders, but LAV significantly increased with age by the 2 methods (Table 1). Interobserver agreement was better using 3D than A-L method (Lin's coefficient = 0.89 and 0.67, respectively). Concordance between the 2 methods was good, with overall Pearson's correlation coefficient R = 0.72 (p<0.001) (Figure 1).

This study is the first to establish normal indexed LAV values by gender and age in a large population of healthy adults with 2 methods, 3D volumetric approach being the most reproducible one. More accurate than TTE and more available than CMR, CCTA may become a reference method to evaluate LAV in various cardiac diseases and normal values definition is thus of importance.

Type of funding sources: None.