Refining Risk Prediction in Systemic Sclerosis-Associated Pulmonary Arterial Hypertension

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.

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.

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.

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.