Refining Risk Prediction in Systemic Sclerosis-Associated Pulmonary Arterial Hypertension.

Background: Pulmonary arterial hypertension (PAH) confers high morbidity and mortality, particularly in patients with systemic sclerosis (SSc), in which right ventricular (RV) adaptation to pulmonary artery (PA) afterload is a key determinant of outcome. Although several clinical risk scores aid in prognostication, their performance in SSc-associated PAH (SSc-PAH) is unclear. The aims of this study were to evaluate the association of established PAH risk scores with mortality in SSc-PAH and to assess whether echocardiographic RV-PA coupling metrics enhance risk discrimination.

Methods: One hundred seventy-four patients with SSc-PAH from the Johns Hopkins Scleroderma Registry who underwent echocardiography within 6 months of invasive confirmation of PAH status were retrospectively analyzed. Patients were followed up for a median of 60.5 months (interquartile range, 34-104 months). Risk scores assessed included COMPERA 2.0 (four strata), REVEAL 2.0, REVEAL Lite 2, and French noninvasive criteria. Echocardiographic coupling metrics included six-segment RV global longitudinal strain, three-segment RV free wall strain (RVFWS), and segmental RVFWS normalized to PA systolic pressure (PASP). Cox regression and Harrell's C index were used to assess 1-year mortality associations. Enhanced models incorporating coupling parameters into each risk score were compared with the original models using likelihood ratio tests.

Results: The study cohort (mean age, 63.6 ± 12.7 years) consisted predominantly of white (76.4%) women (85.6) with limited SSc (86%) and moderate to severe SSc-PAH. Risk score C indices ranged from 0.664 to 0.751. Adding RV global longitudinal strain/PASP, RVFWS/PASP, and midventricular RVFWS/PASP significantly improved mortality prediction (P < .05), yielding the greatest increase in C index across all scores.

Conclusions: In SSc-PAH, established risk scores demonstrate modest discrimination for 1-year mortality. Incorporating echocardiographic parameters of RV-PA coupling significantly improves risk assessment, offering a noninvasive approach to refine prognostication in this high-risk population.