Abstract 16534: Pulmonary Artery Tapering Pattern on Chest CT-Angiogram Predicts Phenotype of Pulmonary Hypertension

Abstract

Introduction: Non-invasive methods to identify phenotype of pulmonary hypertension (PH) are essential to improve the diagnostic algorithm of PH. Hypothesis: Delayed tapering of pulmonary artery (PA) is a signature of pre-capillary PH, while in post-capillary PH, the PA tapers rapidly. This differential tapering pattern of PA can be detected on a chest CT-angiogram (CTA), and quantified as a ratio of main PA diameter to PA branch diameter (right or left) at 5.0 cm length after the PA bifurcation. Methods: We identified 30 subjects with chest CTA and PH confirmed with invasive right heart catheterization (RHC). We identified 3 PH phenotypes: 1. “PVD” (pulmonary vascular disease) = Pre-capillary PH (n=10, PVR>3.0 WU, PAWP <15mmHg), 2. “Mixed” = pre- and post-capillary PH (n=10, PVR>3.0 WU, PAWP >15mmHg), and 3. “PVH” (pulmonary venous hypertension) = post-capillary PH (n=10, PVR<3.0 Woods units [WU], PAWP >15mmHg). Results: The results are summarized in Table. Additional results are expressed as comparison among the three groups in order: PVD vs Mixed vs PVH (mean±SD, % or n, as appropriate). CTA-chest findings: RV basal diameter (mm)= 51.1±8.4 vs 51.0±5.4 vs 38.1±13.9, left ventricular (LV) basal diameter (mm)= 32.1±7.2 vs 31.6±13.3 vs 56.6±15.2*, PA:Ao ratio= 1.1±0.1 vs 1.1±0.2 vs 1.0±0.1. Echo findings: tricuspid annular plane systolic excursion (TAPSE, mm)= 16±3 vs 19±4 vs 22±10*. We performed ROC to identify predictive ability of PA:RPA-5 and PA:LPA-5 to predict PVR>3 WU. The AUC for PA:RPA-5 = 0.859 (p=0.03) and for PA:LPA-5 = 0.812 (p=0.01); with optimal cut-off for both parameters (PA:RPA-5 and PA:LPA-5) was 1.85. Among the overall cohort, the patients with PA:RPA<1.85, 15/16 had PVR>3 and 11/16 were on PH meds. Conclusion: Pattern of PA tapering quantified with PA:RPA-5 or PA:LPA-5 can reliably identify elevated PVR (>3.0 WU). Pre-capillary PH imprints a signature morphological mark on the pattern of PA dilation that can be identified with a CTA-thorax.