Relevance of comorbidities on initial combination therapy in pulmonary arterial hypertension

Rationale: Demographic characteristics of pulmonary arterial hypertension (PAH) patients have changed over time, but the effects of cardiovascular risk factors on risk status and pulmonary vascular resistance (PVR) reduction with initial oral combination therapy are not known. Therefore, we tested the relevance of cardiovascular comorbidities in this setting. Methods: The study enrolled 181 treatment-naive PAH patients with a 6-month (IQR 144-363 days) right heart catheterisation and risk assessment after initial oral combination therapy. Results: Group A included 96 (53.0%) patients without cardiac comorbidities; Group B included 54 (29.8%) patients with one cardiac comorbidity; Group C included 31 (17.1%) patients with two cardiac comorbidities or more. Group C patients were older with a balanced sex distribution. There was a significant difference in PVR reduction moving from the absence to one or at least two cardiac comorbidities, respectively: median -45.0%, -30.3%, -24.3%. A European Respiratory Society/European Society of Cardiology low-risk status was present at first follow-up in 50 (52.0%) patients in Group A, 19 (35.1%) in Group B and 9 (29.0%) in Group C; a REVEAL 2.0 low-risk status was present at first follow-up in 41 (42.0%) patients in Group A, 15 (27.7%) in Group B and 7 (22.6%) in Group C. Group A patients were 2.3 times more likely to achieve/maintain a low-risk status compared with Group B and C (OR 2.27, 95% CI 1.15-4.54, p=0.02). No significant difference was observed between patients with non-cardiac comorbidities and those without comorbidities. Conclusion: Initial oral combination therapy seems associated with a less effective response for patients with cardiovascular comorbidities compared with the others, related to the magnitude of treatment-induced decrease in PVR.