Nintedanib and Sildenafil in Patients with Idiopathic Pulmonary Fibrosis and Right Heart Dysfunction. A Prespecified Subgroup Analysis of a Double-Blind Randomized Clinical Trial (INSTAGE)

Rationale: In the INSTAGE trial in patients with idiopathic pulmonary fibrosis (IPF) and severely impaired gas exchange, nintedanib plus sildenafil was associated with numerical benefits on St. George's Respiratory Questionnaire (SGRQ) total score, brain natriuretic peptide (BNP), and FVC decline versus nintedanib alone. Exploratory analyses of the STEP-IPF (Sildenafil Trial of Exercise Performance in IPF) trial suggested that sildenafil may have a greater effect on SGRQ score in patients with IPF who have right heart dysfunction (RHD).Objectives: Assess whether RHD influenced the effects of nintedanib plus sildenafil versus nintedanib alone in the INSTAGE trial.Methods: Subgroup analyses of patients with (n = 117) versus those without (n = 156) echocardiographic signs of RHD at baseline.Measurements and Main Results: There was no heterogeneity between subgroups by presence of RHD in the effect of nintedanib plus sildenafil versus nintedanib alone on change in SGRQ total score at Week 12 (P = 0.74) or Week 24 (P = 0.90), or change in FVC at Week 12 (P = 0.58) or Week 24 (P = 0.55). In both subgroups, nintedanib plus sildenafil had a numerically greater effect on reducing FVC decline versus nintedanib alone. Between-group differences in change in BNP at Week 24 were -119.9 ng/L (95% confidence interval = -171.3 to -68.5) and -3.6 ng/L (95% confidence interval = -47.2 to 40.0) in patients with and without signs of RHD at baseline, respectively (P < 0.01).Conclusions: In the INSTAGE trial, there were no significant differences in the effects of nintedanib plus sildenafil versus nintedanib alone on changes in SGRQ and FVC between patients with or without echocardiographic signs of RHD at baseline. The benefit of combination therapy on stabilizing BNP was more pronounced in patients with RHD at baseline.Clinical trial registered with www.clinicaltrials.gov (NCT02802345).