Background: Initial combination therapy with an endothelin receptor antagonist (ERA) and riociguat in pulmonary arterial hypertension (PAH) has limited supporting data.
Methods: We performed a prospective, single-arm, open-label trial of riociguat, and ambrisentan for incident PAH patients in functional class III. The primary endpoint was pulmonary vascular resistance (PVR) at 4-months.
Results: Twenty patients (59 ± 13 years old, 85% female) enrolled and 1 died before their 4-month follow-up. Fifteen patients completed a 4-month and 13 completed the 12-month follow-up. At 4-months PVR decreased 54% with an absolute change of -5.8 Wood units (95% CI -4.0; -7.5, p < 0.001). Other hemodynamic variables and risk scores also improved. Six patients discontinued riociguat and 8 discontinued ambrisentan, with 5 (25%) discontinuing both.
Conclusions: These results do not support the routine use of riociguat plus ambrisentan in initial regimens. Future studies are needed to compare this strategy with phosphodiesterase-5 inhibitors and an ERA with respect to tolerability and long-term outcomes.
Keywords: ambrisentan; combination therapy; pulmonary arterial hypertension; riociguat.
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