Left atrial volumes and function: Evaluation with real-time 3D echocardiography in an acute care setting

Background: Limited data are available about feasibility and clinical value of left atrium (LA) quantitative evaluation obtained from real time 3D (RT-3D) echocardiography in critically ills. Objectives: Aims of this study were: 1) to evaluate feasibility of RT-3D echocardiography for LA evaluation in an acute care setting and in a population including a majority of critically ills; 2) to evaluate correlation between two-dimensional (2D) and RT-3D echocardiographic LA quantitative evaluation; 3) to assess clinical consistency and prognostic value of LA measurements obtained from RT-3D images in subjects without CV diseases and in patients with AF and CHF, evaluated in the acute phase of the disease. Patients and Methods: In 382 subjects admitted in the emergency department (ED), we evaluated maximal (Volmax) and minimal (Volmin) LA volumes and LA emptying fraction (LA-EF), from RT-3D images, with a semiautomated border detection program. A follow-up was performed in order to evaluate all-cause mortality and new hospital admission for cardiovascular events. Results: The correlation between measures obtained from 2D and 3D was good (LA Volmax: r = 0.896, P < 0.001; Volmin: r = 0.906, P < 0,001; LA EF: r = 0.749, P < 0.001). Among 77 normal subjects, people aged ≥ 65 years demonstrated comparable LA dimensions with younger subjects (LA Volmax: 25 ± 11 vs 20 ± 7 mL/m2, Volmin: 11 ± 7 vs 8 ± 5 mL/m2). Subjects with normal left ventricular ejection fraction showed LA Volmax significantly lower than patients with LV systolic dysfunction or congestive heart failure (23 ± 11 vs 29 ± 10 vs 33 ± 12 mL/m2, P < 0.05). Patients in atrial fibrillation showed a significantly dilated LA compared with subjects in sinus rhytm (24 ± 11 vs 37 ± 22 mL/m2, P < 0.05). LA dimensions were significantly higher in non-survivors (LA Volmax: 33 ± 9 vs 25 ± 9 mL/m2), in patients with a new hospital admission for cardiovascular disease (LA Volmax: 34 ± 13 vs 23 ± 10 mL/m2) or with a new AF episode (LA Volmax: 40 ± 12 vs 24 ± 11 mL/m2, all P < 0.005). Conclusions: RT-3D evaluation of LA volumes and function is feasible in a non selected series of critically ills. LA dilation was associated with a worse outcome in terms of morbidity and mortality.