Normal values for indexed left atrial end-systolic volume by two- and three-dimensional echocardiography. A cross-sectional population study
Abstract Background The left atrium volume and function gives important prognostic and diagnostic information. Normal values for left atrial end-systolic volume index (LASVI) is derived from 4-chamber and 2-chamber views or three-dimensional (3D) imaging. In current recommendations LASVI above 34 ml/m2 has been regarded dilated when assessing diastolic function and left ventricular filling pressures. It is not known if improved image quality by new scanners or more dedicated atrial focused views provide the same normal reference ranges. Material and methods We examined a large sub-population participating in a population based health study by high-end echocardiographic scanners. LA volume was assessed at end-systole in two-dimensional (2D) recordings focusing on the left atrium to avoid foreshortening. Additionally, 3D full volume recordings were acquired stitching 2–4 cardiac cycles when feasible using breath hold. All echocardiograms were analyzed offline using dedicated commercial software with manual tracing of the endocardial border and calculation of volume by the summation of discs method in 2D recordings. Results 2462 of 5763 invited persons was examined by echocardiography. 1048 persons were excluded due to known heart disease, atrial fibrillation, antihypertensive treatment, diabetes mellitus or findings of clear pathology on echocardiography leaving 1414 persons presumed free of cardiovascular disease or major risk factors for the analyses. Mean ± SD age was 57.9±12.4, and 55.8% was females. Mean (SD) LASVI in females and males were 27.6±9.7 ml/m2 and 30.7±11.1 ml/m2 by 2D imaging, respectively. Similarly, mean ± SD LASVI in females and males were 29.1±6.8 ml/m2 and 30.5±7.9 ml/m2 by 3D. The distribution of LASVI by age is showed in figure 1. The mean ± SD difference between 2D and 3D intra-individual measurements were 0.31±9.0 ml/m2 corresponding to 1.1%. By 2D assessment 24.1% of this presumed healthy cohort had a LASVI over 34 ml/m2, with more males than females had enlarged left atria by this definition (32.7% vs 20.1%, p<0.001). Conclusion New reference ranges for left atrial size is provided for 2D and 3D recordings. By dedicated 2D recordings normal values are larger than previously recorded, and the difference between 2D and 3D recordings are less than previously reported. FUNDunding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): NTNU and the HUNT study Figure 1. Indexed left atrial end-systolic volume, summation of discs method using adjusted left atrial view vs age. The red line denotes 34 ml/m2 used as the cut-off value in present guidelines.