STOP-RIO trial protocol to test riociguat discontinuation safety post-BPA in chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a severe condition often managed with balloon pulmonary angioplasty (BPA). While riociguat, a soluble guanylate cyclase stimulator, is frequently initiated before BPA to mitigate procedural risks, there's a significant lack of evidence supporting its long-term continuation after successful BPA. Current guidelines offer no clear criteria for discontinuing this costly medication, leading many patients to remain on it indefinitely despite potential adverse effects and uncertain benefit. This trial addresses this critical knowledge gap, aiming to optimize post-BPA treatment strategies.

The STOP-RIO study is a multicenter, open-label, randomized, non-inferiority trial. It will enroll 74 adult CTEPH patients who are on riociguat monotherapy and have achieved a mean pulmonary artery pressure (mPAP) <30 mmHg after successful BPA. Participants will be randomized 1:1 to either discontinue riociguat or continue their current medication regimen. The primary endpoint is the between-group difference in baseline-adjusted mPAP at rest, measured by right heart catheterisation at 16 weeks.