Correlation Between Right Atrial Function and Invasively-Measured Pulmonary Pressures in Patients with Pulmonary Arterial Hypertension

Abstract

Right atrial (RA) enlargement is a measure of right ventricular (RV) overload and a prognostic marker of poorer outcomes in patients with pulmonary arterial hypertension (PAH). There are emerging reports suggesting that RA function may have predictive value in this population, however correlation with pulmonary pressures measured via invasive right heart catheterisation has not been well characterised. We sought to assess the correlation between RA strain (RAs), a novel echocardiographic measure of RA function, and invasively-derived pulmonary arterial pressures (PAP). Patients with Type-1 PAH referred to our institutional pulmonary hypertension clinics between Jan-2017 and Dec-2020 were evaluated. Patients who underwent transthoracic echocardiography within 4-weeks of right heart catheterisation were included. RAs was measured with vendor-independent software (TomTec Image Arena). Our cohort consisted of 43 patients (58.4±20.3 yrs, 70% female). All patients had normal left ventricular systolic function and the mean BMI was 28.6±7.7. 54% of patients had a dilated RV and 87% had impaired RV function by RV free wall strain. 39% of patients had increased indexed RA volumes. The mean RAs was 22.3±8.5%. RAs demonstrated a moderate positive correlation with RA emptying fraction (r = 0.511, p<0.05) and a moderate inverse correlation with RA minimum volume (r = -0.53, p<0.05) and invasively derived RA pressures (r = -0.58, p<0.05). There was no significant correlation between RAs and parameters of RV size and function, but RAs interestingly showed a strong inverse correlation with invasively derived mean PAP (r = -0.81, p<0.01). RAs had a close correlation with invasively measured mean PAP. Further studies are required to further examine this relationship.