Prognostic Value of Echocardiographic Coupling Metrics in Systemic Sclerosis–Associated Pulmonary Vascular Disease

Background: Ineffective right ventricular (RV) adaptation to increasing pulmonary arterial (PA) afterload in pulmonary vascular disease (PVD) significantly contributes to morbidity and mortality. Pulmonary vascular disease in systemic sclerosis (SSc) arises through various mechanisms, yet detecting abnormal contractile response remains challenging. Here we examine whether echocardiographic RV-PA coupling metrics correlate with invasive pressure-volume (PV) loops, enhancing the prediction of adverse clinical outcomes in SSc-PVD patients. Methods: Prospectively enrolled patients with SSc-PVD with paired echocardiogram and PV loops were included. Linear regression and receiver-operating curve analysis were used to assess the relationship between tricuspid annular plane systolic excursion/PA systolic pressure (PASP), fractional area change/PASP, tissue Doppler velocityS’/PASP, and RV free wall strain (RVFWS)/PASP and coupling thresholds defined by end-systolic to end-arterial elastance (Ees/Ea), obtained by the multibeat method. The contribution of right atrial strain (RAS) to RV-PA coupling parameters was also investigated. Kaplan-Meier analysis was used to identify the relationship between coupling ratios and composite outcomes including clinical worsening, lung transplant, and death. Results: Forty-two patients with SSc were studied, 91% female, with a mean age of 59 ± 12 years and varying degrees of PVD: mean pulmonary artery pressure 29.5 ± 12.8 mm Hg, PVR 4.7 ± 4.2 WU, and PCWP 10.3 ± 4.1 mm Hg. Echocardiographic coupling metrics including tricuspid annular plane systolic excursion/PASP, fractional area change/PASP, tissue Doppler velocity S’/PASP, RVFWS_global and RVFWS_basal/PASP, and RAS_reservoir/PASP were linearly associated with Ees/Ea. At cut points obtained through receiver-operating curve analysis, all ratios were predictive of RV-PA uncoupling, defined by Ees/Ea, and composite outcomes. Additionally, RAS_reservoir/RVFWS correlated with Ees/Ea even after adjustment for PASP, suggesting that diminished RAS further impacts RV performance and coupling. Conclusion: Echocardiographic RV-PA coupling ratios strongly correlate with invasive Ees/Ea and predict adverse clinical outcomes in SSc patients across the spectrum of PVD. Further, we demonstrate how RAS impacts RV performance. These findings may refine risk stratification and prognostication in this at-risk cohort.