BACKGROUND: Right ventricular functional adaptation to afterload is a major determinant of outcome in pulmonary arterial hypertension (PAH). We aimed to investigate if right ventricular-pulmonary artery (PA) coupling evaluated by the ratio of tricuspid annular plane systolic excursion (TAPSE) to systolic pulmonary artery pressure (sPAP) improves risk assessment scores for survival prediction. METHODS: A total of 677 consecutive patients with PAH (55% idiopathic) were prospectively enrolled with follow-up clinical, right heart catheterization, and echocardiographic evaluations within 12 months (interquartile range, 180–344 days) after initiation of targeted therapies in 11 Italian centers. European Society of Cardiology/European Respiratory Society guidelines-derived risk scores and REVEAL 2.0 (US Registry to Evaluate Early and Long-Term PAH Disease Management 2.0) risk scores were collected at baseline and follow-up. 254 consecutive patients with PAH retrospectively enrolled in a German reference center served as a validation cohort. RESULTS: A low-risk status at a median of 3.7 years (interquartile range, 1.2–6.8) follow-up was significantly associated with each unit (0.1 mm/mm Hg) increase in TAPSE/sPAP under targeted therapies (European Society of Cardiology/European Respiratory Society score: odds ratio, 1.78; P ≤0.001; REVEAL 2.0 score: odds ratio, 1.43; P ≤0.001). At follow-up, the TAPSE/sPAP ratio increased the prognostic information of each risk stratum of the European Society of Cardiology/European Respiratory Society risk score, except the highest risk stratum, with 0.5 mm/mm Hg, 0.35 mm/mm Hg, and 0.30 mm/mm Hg, from the lowest to the intermediate-high risk score, identified as the best cutoff value. TAPSE/sPAP ratio increased the prognostic information of the REVEAL 2.0 score at follow-up, with 0.35 mm/mm Hg identified as the best cutoff value to discriminate within a score of 5 to 8, with no added value for scores 8. These results were confirmed in the validation cohort. CONCLUSIONS: Assessment of right ventricular-PA coupling by the TAPSE/sPAP ratio in PAH improves risk assessment scores except in the lowest or most advanced stage of the disease

Pulmonary arterial hypertension (PAH) is a rare, progressive disease with a poor prognosis. The pathophysiologic model is mainly characterized by an afterload mismatch in which an increased right ventricle afterload, driven by increased pulmonary vascular resistance (PVR), leads to right heart failure. International guidelines recommend optimization of treatment based on regular risk assessments to achieve or maintain a low-risk status. Current risk scores are based on a multi-modality approach, including demographic, clinical, functional, exercise, laboratory, and hemodynamic parameters, which lack significant echocardiographic parameters. The originality of echocardiography relies on the opportunity to assess in a non-invasive way a physiologically meaningful combination of easy to measure variables tightly related to right ventricle adaptation/maladaptation to increased afterload, the main determinant of a patient’s prognosis. Echo-derived morphological and functional parameters have been investigated in PAH, proving to have prognostic relevance. Different therapeutic strategies proved to have different effects in reducing PVR. An upfront combination of drugs, including a parenteral prostacyclin, has shown to be associated with right heart reverse remodeling in a greater proportion of patients than other treatment strategies as a function of PVR reduction. Adding echocardiographic data to current risk scores would allow better identification of right ventricle (RV) adaptation in PAH patients’ follow-up. This additional information would allow better stratification of the patient, leading to optimized and personalized therapeutic management.