Left atrial enlargement: transverse versus anteroposterior diameter, which is more reliable?

Abstract

Introduction: The enlargement of the left atrium is associated with poor prognosis regardless of its etiology. The anteroposterior diameter, so widely used for years, does not present a good correlation with atrial enlargement, perhaps because the growth in most cases is not symmetrical. There is scarce bibliography that considers the septolateral diameter in the evaluation of atrial size. Objective: To compare a "new" way of measuring the left atrium, in a transverse direction, with the anteroposterior one, so widely used, and to establish their diagnostic precision for enlargement of the chamber. Methods: There were 201 patients analyzed, in whom the biplane indexed volume was calculated by the method of disks to establish enlargement. The transverse diameter of the left atrium was measured at the mid-level, from a 4-chamber apical view, taking 4 cutoff points (38, 39, 40 and 41 mm) and establishing sensitivity, specificity, negative predictive value, positive predictive value, Youden index and area under the curve. Results: The transverse evaluation of the left atrium was superior to the anteroposterior measurement to diagnose enlargement, easy and quick to perform, with a cutoff value of 39 mm, although it presents inferiority with respect to the estimation by area.