CT pulmonary angiography-derived right atrial area can risk stratify patients with PAH and PH

Purpose: Right atrial (RA) area on echo and mean RA pressure (mRAP) at right heart catheterisation have prognostic value in PH and are included in ERS risk stratification tables. CT pulmonary angiography (CTPA) is commonly performed on patients with unexplained breathlessness and suspected PH. However, prognostic value of RA measured on CTPA in PH has not been studied. Aims: Investigate if CTPA RA area (CT RAx) correlates with mRAP. Secondarily, to assess if CTPA RAx can be used to risk stratify into low, medium & high-risk groups. Methods: 410 patients with PH, including 158 with pulmonary arterial hypertension (PAH), who underwent baseline CTPA and RHC within 90 days were identified from the ASPIRE registry. Pearson correlation between CT RAx and mRAP was assessed. Cohort was divided by ERS mRAP thresholds into low, medium & high risk ( 14 mmHg) and CT RAx difference between groups assessed with one-way ANOVA. Outcomes were assessed with Kaplan-Meier and Cox proportional hazards regression analysis. Results: During the follow up period, 89 patients died, 54 of whom had PAH. Mean survival was 4.7 for PH and 4.4 years for PAH. CT RAx correlated well with mRAP in both PH (r=0.482, p Conclusion: RA area measured on CTPA is a simple axial measurement which correlates with mRAP and predicts survival. Further studies to identify optimal CT prognostic thresholds is warranted.