Different approaches for the assessment of left atrial volume in a large sample of patients undergoing an echocardiogram for cardiovascular risk stratification

Objective: Left atrial (LA) enlargement (LAE) is associated to an increased risk of cardiovascular complications, and in particular of atrial fibrillation. When LA size is measured by echocardiography, LA volume measurement is preferred over linear measurements. In fact, the strength of the relationship between cardiovascular diseases is stronger for LA volume than for LA linear dimensions. Recently it has been proposed a new method (LAV_e) to estimate LA volume in order to provide a surrogate of biplane LA volume when direct measurement is not available. The aim of our study was to evaluate the correlation between LA volume assessed by the biplane method(LAV_bip) and LA volume estimated by the linear measurements(LAV_e) and to assess the prevalence of LA enlargement in a large sample of patients undergoing an echocardiogram for cardiovascular risk stratification at an ESH excellence centre in Italy. Design and method: 4941 subjects undergoing a diagnostic work-up for arterial hypertension (known or suspect) were analysed. LAV_bip was assessed as by the area-length method using the apical 4-chamber and 2-chamber views and LAV_e was calculated according to the formula: 2.323*(LA parasternal linear diameter2.071). LAV was indexed to height2.Results: Mean age was 56 ± 16 years, BMI 26 ± 5, 43% of subjects had normal weight, 39% overweight, 18% obese, 54% males, 84 % were hypertensives.Mean LAV_bip was 46.2 ± 18.4 and LAV_e was 35.4 ± 11.6 ml. Mean LAV_bip/h2 was 16.2 ± 6.3 and LAV_e/h2 was 12.4 ± 4.1 ml/h2. The correlation coefficients between the two variables were respectively 0.62 and 0.60 (p < 0.0001). Bland & Altman analysis showed a progressive increase in discrepancy between the two measures with increasing LAV_bip. The prevalence of LA enlargement was 32% with the biplane method and 10 % with the elliptical estimation. Conclusions: In a large sample of subjects undergoing a diagnostic work-up for arterial hypertension we observed a possible underestimation of LAV and a lower prevalence of left atrial enlargement when the elliptical approach is used. These results, if confirmed in other populations, suggest that direct measurement of left atrial volume should be preferred, if available.