Risk stratification refinements with inclusion of haemodynamic variables at follow-up in patients with pulmonary arterial hypertension.

BACKGROUND AND AIMS: Haemodynamic variables are prognostic factors in pulmonary arterial hypertension (PAH). However, right heart catheterization (RHC) is not systematically recommended to assess the risk-status during follow-up. This study aimed to assess the added value of haemodynamic variables in prevalent patients to predict the risk of death or lung transplantation according to their risk status assessed by the non-invasive 4 strata model as recommended by the European guidelines.

METHODS: We evaluated incident patients with PAH enrolled in the French PAH Registry between 2009 and 2020 who had a first follow-up RHC. Cox regression identified, in each follow-up risk status, haemodynamic variables significantly associated with transplant-free survival (TFS). Optimal thresholds were determined by time-dependent Receiver-Operating Characteristics. Several multivariable Cox regression models were performed to identify the haemodynamic variables improving the non-invasive risk stratification model.

RESULTS: We analysed 1240 incident patients reassessed within a year by RHC. None of haemodynamic variable were significantly associated with TFS among low-risk (n=386) or high-risk (n=71) patients. Among patients at intermediate (-low, n=483, -high, n=300) risk at first follow-up, multivariable models including either stroke volume index (SVi) or mixed venous oxygen saturation (SvO2 ) were the best. The prognostic performance of refined 6 strata risk stratification model including the non-invasive 4 strata model and SVi>37 mL·m-2 and/or SvO2 >65% for patients at intermediate-risk (Area Under the Curve 0.81, c-index 0.74), was better than that of 4 strata model (0.79, p=0.009; c-index 0.72).

CONCLUSIONS: Cardiopulmonary haemodynamics may improve risk stratification at follow-up in patients at intermediate-risk.