Background: There is limited evidence for pulmonary arterial hypertension (PAH)-Targeted therapy in patients with pulmonary hypertension associated with respiratory disease (R-PH). Therefore, we conducted a multicenter prospective study of patients with R-PH to examine real-world characteristics of responders by evaluating demographics, treatment backgrounds, and prognosis. Methods and Results: Among the 281 patients with R-PH included in this study, there was a treatment-naive cohort of 183 patients with normal pulmonary arterial wedge pressure and 1 of 4 major diseases (chronic obstructive pulmonary diseases, interstitial pneumonia [IP], IP with connective tissue disease, or combined pulmonary fibrosis with emphysema); 43% of patients had mild ventilatory impairment (MVI), whereas 52% had a severe form of PH. 68% received PAH-Targeted therapies (mainly phosphodiesterase-5 inhibitors). Among patients with MVI, those treated initially (i.e., within 2 months of the first right heart catheterization) had better survival than patients not treated initially (3-year survival 70.6% vs. 34.2%; P=0.01); there was no significant difference in survival in the group with severe ventilatory impairment (49.6% vs. 32.1%; P=0.38). Responders to PAH-Targeted therapy were more prevalent in the group with MVI. Conclusions: This first Japanese registry of R-PH showed that a high proportion of patients with MVI (PAH phenotype) had better survival if they received initial treatment with PAH-Targeted therapies. Responders were predominant in the group with MVI.
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