Acute right heart failure (RHF) represents a life-threatening complication in patients with pulmonary hypertension (PH), including pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. This Phase 2 randomized controlled trial, published in the Circulation Journal, assessed the efficacy and safety of inhaled nitric oxide (iNO), a rapid-acting pulmonary vasodilator, in this high-risk population.

A total of 30 patients with acute severe RHF secondary to PH were randomized in a 1:1 ratio to receive either iNO or no iNO (control group). The primary endpoint was the change in pulmonary vascular resistance (PVR) from baseline to 30 minutes following iNO initiation or assignment in the control group. PVR decreased in the iNO group compared with control (mean ± SD: −2.41 ± 2.47 vs 0.8 ± 1.03 Wood units), with a between-group difference of −3.21 Wood units (95% CI: −4.633 to −1.785).

Secondary endpoints, including serum B-type natriuretic peptide (BNP) levels and inferior vena cava (IVC) diameter, decreased significantly in the iNO group over the 7-day observation period. No serious adverse events, including methemoglobinemia, were reported during the study.

These results show reductions in pulmonary vascular resistance along with decreases in BNP levels and inferior vena cava diameter. They suggest that iNO may be a potential acute treatment option in RHF due to PH.