Marked improvement in severe pulmonary arterial hypertension following airway infection in a patient with a heterozygous BMP9 nonsense mutation: a case report.

Background: Pulmonary arterial hypertension (PAH) is a severe and life-threatening disease. Genetic factors, inflammation and immune system play important roles in their pathogenesis. However, their precise roles are still not fully understood. Case summary: A woman was diagnosed with PAH at age 12 due to dyspnoea and syncope on exertion. Genetic testing at that time revealed a heterozygous BMP9 mutations (c. 451C>T; p. Arg151Ter). Despite receiving combination therapy with macitentan, riociguat, and intravenous epoprostenol, she continued to have severe pulmonary hypertension with suprasystemic pressure [mean pulmonary artery pressure (PAP) = 65 mmHg] for 4 years following treatment initiation. At the age of 17, she was admitted to the hospital because of an airway infection (AI). Cardiac catheterization performed 3 months after an AI revealed a considerable improvement in the mean PAP, which had decreased to 24 mmHg. This improvement was sustained even 1 year after the AI. Discussion: A patient with severe, treatment-resistant pulmonary hypertension exhibiting a dramatic improvement in pulmonary pressure following an AI is exceedingly rare. The present case may provide new insights into the pathophysiology of PAH.