P961 Diagnostic use of proportion between ascending aorta and left atrium in patients referred for coronary artery calcium scoring

Abstract Background Non-contrast-enhanced cardiac computed tomography (NCE-CCT) is currently used for coronary artery calcium (CAC) scoring. Meanwhile, other cardiac, vascular and extra-cardiac structures can be evaluated. Data about ascending aorta (AA) and left atrium (LA) has been quantified separately in a few studies. Their mutual proportion has not been examined, as yet. Aim. We hypothesize that mutual proportion between AA and LA size might help for diagnosing their enlargement before absolute cut-off values are reached. Method Among 7950 patients who had NCE-CCT with a 64 raw scanner (Aquillion, Toshiba) within the last decade in our center, in 797 persons the AA diameter (at the level of pulmonary artery bifurcation) and LA diameter and area (highest value) were measured. Raw AAD values were qualified as abnormal if exceeded upper normal limit UNL) for age and height. Weight, BMI and BSA has not been used in order to avoid falsified results in obese patients. The ratio AAD:LAD was quantified as low (<0.8), normal (0.8-1.2) and high (>1.2). Results There were 45 patients (5.6%) who had AAD higher than age-height predicted UNL, including 24 patients with a raw AAD >43mm (3.0%). The other 752 has their AAD within limits. The means of AAD were 42.9 ± 3.2mm and 33.6 ± 3.6mm (p < 0.001). LA size differed significantly, both in diameters 38.5 ± 7.4 vs 34.2 ± 5.6mm (p < 0.001) and areas 2138 ± 593 vs 1837 ± 481 mm2 (p < 0.001). Data regarding mutual relationship are shown in the fig.1. It is seen that normal mutual proportion (AOLARel =1) in patients with high AAD means that LAD was also increased (left graph, red open square). In 603 patients with normal AAD corresponded with normal LAD. The AAD:LAD >1.2 in 845 subjects might suggest increased AAD in spite to normal raw diameter. Similar rules were found in respect to the LA area. Conclusions Ascending aorta and left atrium enlargement are infrequently recognized in patients referred to CAC scoring. Mutual proportion between AA and LA size might complement diagnostic approach of their abnormalities.