The added value of right ventricular function normalized for afterload to improve risk stratification of patients with pulmonary arterial hypertension

Background: Risk stratification is central to the management of pulmonary arterial hypertension (PAH). For this purpose, multiparametric tools have been developed, including the ESC/ERS risk score and its simplified versions derived from large database analysis such as the COMPERA and the French Pulmonary Hypertension Network (FPHN) registries. However, the distinction between high and intermediate-risk profiles may be difficult as the latter lacks granularity. In addition, neither COMPERA or FPHN strategies included imaging-derived markers. We thus aimed at investigating whether surrogate echocardiographic markers of right ventricular (RV) to pulmonary artery (PA) coupling could improve risk stratification in patients at intermediate-risk. Material and methods: A single-center retrospective analysis including 102 patients with a diagnosis of PAH was performed. COMPERA and FPHN strategies were applied to stratify clinical risk. The univariate linear regression was used to test the influence of the echo-derived parameters qualifying the right heart (right ventricle basal diameter, right atrial area, and pressure, tricuspid regurgitation velocity, tricuspid annular plane systolic excursion -TAPSE-). Among these, the TAPSE and tricuspid regurgitation velocity ratio (TAPSE/TRV) as well as the TAPSE and systolic pulmonary artery pressure ratio (TAPSE/sPAP) were considered as surrogate of RV-PA coupling. Results: TAPSE/TRV and TAPSE/sPAP resulted the more powerful markers of prognosis. Once added to COMPERA, TAPSE/TRV or TAPSE/sPAP significantly dichotomized intermediate-risk group in intermediate-to-low-risk (TAPSE/TRV≥3.74 mm∙nm/s)-1 or TAPSE/sPAP≥0.24 mm/mmHg) and in intermediate-to-high-risk subgroups (TAPSE/TRV<3.74 mm∙(m/s)-1 or TAPSE/sPAP<0.24 mm/mmHg). In the same way, TAPSE/TRV or TAPSE/sPAP was able to select patients at lower risk among those with 2, 1, and 0 low-risk criteria of both invasive and non-invasive FPHN registries. Conclusions: Our results suggest that adopting functional-hemodynamic echo-derived parameters may provide a more accurate risk stratification in patients with PAH. In particular, TAPSE/TRV or TAPSE/sPAP improved risk stratification in patients at intermediate-risk, that otherwise would have remained less characterized.