Abstract 13924: Four-Tier Classification of Pulmonary Artery Metric Severity for Diagnosis and Prognosis of Pulmonary Hypertension

Introduction: Increased main pulmonary artery diameter (mPA) and ratio of mPA to ascending aortic diameter (ratio PA) on computed tomography (CT) are associated with pulmonary hypertension (PH). We aimed to develop a four-tier severity classification of mPA and ratio PA for diagnosis of PH. Methods: In 228 patients (136 with PH) undergoing right heart catheterization (RHC) and CT for dyspnea, we measured mPA and ratio PA. Using a derivation cohort (n=114), we determined cutpoints for four tiers of mPA and ratio PA severity to maximize sensitivity and specificity, and confirmed these values in a validation cohort (n=114). Results: Figure A shows the 4-tier cutpoints for mPA and ratio PA as Framingham sex-specific normal, mild, moderate, and severe. The 4-tier classification of mPA and ratio PA successfully predicted PH (derivation: both c-stats 0.90; validation: both c-stats 0.85). The sensitivity of the normal tier was 99% for mPA and 93% for ratio PA, while the specificity of the severe tier was 98% for mPA and 100% for ratio PA. With increasing severity of mPA and ratio PA tiers, there was a corresponding increase in the proportion of patients with elevated RHC Mean Pulmonary Artery Pressure (Figure A) and Echo Right Ventricular Systolic Pressure (both p<0.001). Patients with moderate to severely enlarged mPA had worse survival than those with normal or mildly enlarged mPA (Figure B). Similar results were seen with ratio PA. Conclusions: Non-invasive CT four-tier classification of mPA and ratio PA has high diagnostic accuracy for PH and can easily be used clinically. Higher severity of mPA and ratio PA are also associated with worse prognosis.