Reference values of left atrial size and function according to age: should we redefine the normal upper limits?

Different cut-offs have been proposed for left atrial (LA) size. Furthermore, conflicting results have been reported about the influence of age on LA size and data on the impact of age on LA myocardial function are scanty. The aim of this study was to derive references values for LA size and function in healthy subjects and to evaluate the impact of age. We conducted a systematic literature search of MEDLINE database. We included only studies evaluating healthy subjects, with age ranged between 18 and 80 years. Parameters were compared among four age groups, < 30, 30–45, > 45–60, > 60 years. Three hundred twenty-six studies met the inclusion criteria and the final population consisted of 62,821 subjects. LA volume index (LAVi) did not differ among different age groups (p = 0.21). The normal upper limit of LAVi was 24 mL/m². LA reservoir function, measured by strain, did not differ among age groups (38 ± 3%, 32–43%; p = 0.74). Left ventricular (LV) size and function were not different among groups, except LV mass index. A decrease in E/A ratio and an increase in E/e′ ratio were found with advancing age (p < 0.0001 and p = 0.001, respectively). In healthy subjects the normal upper limit of LAVi was lower than that recommended and is not influenced by advancing age. Furthermore, also LA function measured by strain was not affected by age. The current reference values of LAVi should be used with caution when applied to healthy subjects.