Abstract 16351: Reference Equations for Pulmonary Artery Size and Pulsatility Using Echocardiography in Pulmonary Arterial Hypertension

Background: A main pulmonary artery (MPA) diameter>25 mm on echocardiography is supportive of the diagnosis of pulmonary hypertension according to the most recent European Society of Cardiology guideline. [1]. The size of the pulmonary artery may however vary according to body size, age and sex and these considerations may be important for diagnostic purposes. Objectives: (1) to derive reference equations for MPA and right pulmonary artery (RPA) size on echocardiography that consider the effect of body size, age and sex; (2) to determine which measure of PA size better classifies pulmonary arterial hypertension (PAH) when compared to controls. Method: 248 healthy males and females were recruited as part of Stanford aging study and 200 patients with PAH have been retrospectively included from the Stanford Adult PH Program. The diameters of the MPA and RPA were measured from the parasternal short axis. The RPA diameter, area, and pulsatility index were measured from the supra sternal notch view. MedCalc Version 20.2018 statistical software program was used for modeling and assessing the variance function. Results: Multivariate regression analysis was used to derive PA size reference equations that consider sex, age, and height. Age retained in all the models and height was the second most influential variable. Using a Z score threshold of 1.96, for the diastolic MPA diameter size yielded an area under the ROC curve (AUC) of 0.91, 87.15% sensitivity and 95.19% specificity to detect PAH. In comparison, the AUC for absolute MPA size >25 mm during diastole and systole yields 0.87 and 0.67, respectively which was significantly different from the z score AUC (Figure-1). Conclusion: Our study develops echocardiography reference equations for PA size accounting for the influence of age, height, and sex that can potentially refine PAH diagnostic algorithms if further validated.