Patients with advanced IPF (diffusing capacity for carbon monoxide ≤40% predicted) and risk of Group 3 PH (defined as mean pulmonary arterial pressure ≥20 mm Hg with pulmonary arterial wedge pressure ≤15 mm Hg on a previous right-heart catheterisation [RHC], or intermediate/high probability of Group 3 PH as defined by the 2015 European Society of Cardiology/European Respiratory Society guidelines) are eligible.