Reference values for aortic diameters obtained using both inner-­edge-­to-­inner-­edge and leading­-edge-­to-­leading-­edge methods in 190 healthy subjects

ASE/EAE guidelines suggest to measure aortic diameters (AoD) using the leading edge-to-leading edge method (LEM), whereas ACC/AHA ones favor the inner edge-to-inner edge method (IEM) to increase reproducibility and consistency with MRI and CT. To obtain reference values of the AoD by transthoracic echocardiography using both LEM and IEM and to compare them, we prospectively studied 190 healthy volunteers (82 men, 44 + 14 years, range 18-80 years), using a Vivid E9 (GE Healthcare, Horten, Norway) with M5S probe and 2nd-harmonic imaging. On 2D images optimized for the aortic root and ascending aorta, a single observer performed offline measurements using LEM and IEM at the level of the aortic root (Ao-R), sino-tubular junction (STJ) and ascending aorta (AscAo, 1 cm from the STJ) at end-diastole (at R-wave on ECG). Reference AoD with both methods are reported in Table. As expected, at Bland-Altman’s analysis all AoD measured using LEM were significantly larger than those measured using IEM: Ao-R (bias= 3.1 mm; 95% LOA 0.9 – 5.3); STJ (bias=3.5 mm; 95% LOA 0.7 – 6.3), and AscAo (bias= 3.2 mm; 95% LOA 0.7 – 5.7). At multivariable regression analysis (including age, gender, body surface area (BSA), height, systolic blood pressure), age and BSA (adjusted R2= 0.42), were independent predictors of Ao-R diameters with both methods, while age, BSA and gender (adjusted R2 = 0.44) were independent predictors of AscAo diameter. Intra- and inter-observer variability was similar between LEM and IEM methods (2% vs 2%, p= 0.63, and 4% vs 5%, p=0.23 for AoR, respectively; and 3% vs 2%, p= 0.26, and 4% vs 6%, p= 0.15 for AscAo, respectively). This is the first report about reference values of the AoD obtained using both LEM and IEM, the difference in diameter measurement between the two methods, and the independent determinants of them in a largee population of healthy subjects.