Comparison of hemodynamic parameters in treatment-naive and pre-treated patients with pulmonary arterial hypertension in the randomized phase III PATENT-1 study

Science and Research

BACKGROUND: Detailed hemodynamic data from the phase III PATENT-1 study of riociguat in patients with pulmonary arterial hypertension (PAH) were investigated. METHODS: Patients with PAH who were treatment naive or pre-treated with endothelin receptor antagonists or non-intravenous prostanoids were randomly assigned to riociguat up to 2.5 mg 3 times a day or placebo. Hemodynamic parameters were assessed at baseline and week 12. RESULTS: Riociguat significantly decreased pulmonary vascular resistance in treatment-naive (n = 221; least squares [LS] mean difference -266 dyneseccm(-5) [95% confidence interval (CI) -357 to -175; p < 0.0001]) and pre-treated (n = 222; LS mean difference -186 dynesec cm(-5) [95% CI -252 to -120; p < 0.0001]) patients and significantly increased cardiac index (LS mean difference +0.7 [95% CI 0.5 to 0.8] and +0.5 [95% CI 0.3 to 0.7], respectively [both p < 0.0001]). Mean pulmonary artery pressure (p = 0.0056 and p = 0.0019 for treatment-naive and pre-treated patients, respectively), mean arterial pressure (both p < 0.0001), and systemic vascular resistance (both p < 0.0001) were significantly reduced, and there was an increase in mixed venous oxygen saturation (p < 0.0001 and p = 0.0004, respectively). Results were similar in patients pre-treated with endothelin receptor antagonists and patients pre-treated with non-intravenous prostanoids. Improvements in 6-minute walking distance correlated very weakly with improvements in pulmonary vascular resistance (r = -0.21 [95% CI -0.30 to -0.11; p < 0.0001]) and cardiac index (r = 0.16 [95% CI 0.06 to 0.25; p < 0.0016]). CONCLUSIONS: Riociguat significantly improved hemodynamic parameters in pre-treated and treatment-naive patients with PAH.