Abstract 2349: Left Atrial Volume Reclassified: Application of the American Society of Echocardiography Cut-Offs to Unselected Asymptomatic Subjects Referred to the Echocardiography Laboratory.
Background The recently published American Society of Echocardiography recommendations concluded that left atrial (LA) volume indexed to body surface area (LAVi) should be preferred over LA diameter (LAD) because of the fewer geometrical assumptions and because it is a better predictor of adverse outcomes. However, many laboratories continue to use LAD because it appears easier to measure.
Objective To determine whether classification of abnormal LA based on volumes results in reclassification of LA size if the diameters were measured.
Methods 588 (mean age 66±14, 56% women) unselected consecutive asymptomatic subjects referred to the outpatient echo lab in 2006 had antero-posterior LAD measured by M-mode from parasternal long axis view and LAV calculated by biplane Simpson method from 2- and 4 chamber views by experienced echocardiographers. LAD>39 mm for women and LAD>41mm for men, LAVi >29 mL/m2 for both sexes identifies abnormal LA.
Results Although there was a moderately good linear correlation between LAVi and LAD (r=0.67, p<0.001) (Fig⇓), when the published cut-offs were used, 311 (53%) subjects had abnormal LA by LAD and 449 (76%) by LAVi (p<0.001). Indeed, 158 (27%) of 277 subjects who were classified as normal by LAD had abnormal LAVi (k=0.38, p<0.001). Conversely, when LAD was abnormal (n=311) almost all subjects had abnormal LAVi (n=291, 94%).
Conclusion Measurement of LA by LAVi allows identification of patients with enlarged atria that would have been missed if classified by LAD. This may lead to underestimate the true prevalence of enlarged LA and to preclude patients to receive adequate treatment or prevention.