Pulmonary Hypertension Associated with Interstitial Lung Disease: A Review on Diagnosis and Treatment with a Focus on Emerging Therapies

Background: Pulmonary hypertension (PH) complicating interstitial lung diseases (ILDs) is critical for symptom burden and prognosis. The prevalence of PH varies according to ILD subgroups and severities. Establishing the diagnosis of PH associated with ILDs (PH-ILDs) is complex due to overlapping symptoms, late clinical signs, and poor diagnostic performance of routine noninvasive diagnostic methods. Summary: Treatment options for PH-ILDs are limited and target mainly the underlying parenchymal lung disease. For decades, clinical trials of PH-ILD treatment using pulmonary vasodilators have failed showing no benefits or even harm. Thus, most PH-specific therapies are contra-indicated in PH-ILDs. Recently, the landmark INCREASE trial showed that inhaled treprostinil improved exercise capacity (6-min walking distance) and NT-proBNP, stabilized forced vital capacity, and reduced clinical worsening. Inhaled treprostinil was approved by the FDA in 2021, while approval in Europe and Switzerland is pending. Key Message: After its approval in Europe and Switzerland, the optimal use of inhaled treprostinil will require a careful patient selection with comprehensive assessments (including right heart catheterization) by highly specialized expert centers treating patients with both PH and ILDs.