Left Atrial Volume Is Superior to the Ratio of the Left Atrium to Aorta Diameter for Assessment of the Severity of Patent Ductus Arteriosus in Extremely Low Birth Weight Infants

Background: This study was undertaken to establish the appropriate correction of left atrial volume (LAV) to body surface area (BSA) to provide reference values and to assess the hypotheses that LAV is useful for assessing patent ductus arteriosus (PDA) severity in extremely low birth weight infants (ELBWI) and could overcome the limitations of the LA-to-aortic dimension ratio (LA/Ao). Methods and Results: Echocardiograms with 318 data points from 53 consecutive ELBWIs were assessed. PDA surgery was performed within the first 2 weeks in 6 patients. LAV was measured using the biplane (LAV) and single-plane (LAV(4CV)) area-length methods. The allometric model was used to correlate LAV to BSA. LAV(4CV) had a good correlation with LAV (R=0.93). Although LAV/BSA(1) had a residual relationship with BSA, LAV/BSA(1.54) (23.5 +/- 9.3 ml/m(3.08)) and LAV(4CV)/BSA(1.52) (21.4 +/- 9.4 ml/m(3.04)) did not. Receiver-operating characteristic analysis to detect hemodynamic status just before PDA surgery showed the superiority of LAV/BSA(1.54) (area under the curve (AUC) 0.97) and LAV(4CV)/BSA(1.52) (AUC 0.98) over LA/Ao (AUC 0.92). Moreover, LAV/BSA(1.54) and LAV(4CV)/BSA(1.52) were better correlated with left pulmonary arterial end-diastolic velocity than was LA/Ao. Conclusions: This study provided appropriate BSA correction of LAV and its reference values in ELBWIs. LAV indices may be superior to LA/Ao for PDA severity assessment. Measurement of single-plane LAV is easy, with similar usefulness to biplane LAV.