Research Background

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare disease (approximately 3,000 patients in Japan), in which organized thrombotic material forms in the pulmonary arteries, impairing the pulmonary circulation.

Several therapeutic approaches are recommended in major domestic guidelines (Class I): these include anticoagulant therapy to prevent the formation and growth of thrombi in the pulmonary arteries; Riociguat administration to dilate the pulmonary vasculature; pulmonary endarterectomy (PEA) to physically remove organic thrombi; and percutaneous balloon pulmonary angioplasty (BPA) to widen stenotic or obstructed vessels to improve the circulation. However, the small number of CTEPH patients means that little empirical data is available supporting these approaches’ efficacy and safety, leaving doctors to select treatment plans without strong evidence. Furthermore, a large-scale controlled clinical trial would be infeasible given the tiny population of affected patients. Instead, research must focus on maximally utilizing real-world, observational data to create evidence supporting the efficacy and safety of different CTEPH treatments.