Meldonium Improves Functional Capacity in Patients with Right Ventricular Failure

<b>Background/Objectives:</b> Right ventricular (RV) failure (RVF) is associated with poor prognosis and currently has no known treatment. Meldonium is a clinically used cardiometabolic drug that improves RV function in a preclinical RVF model. This study aimed to assess the safety and efficacy of meldonium in patients with pulmonary arterial hypertension (PAH)-induced RVF. <b>Methods:</b> Twenty RVF patients received meldonium (500 mg, b.i.d.) for 30 days; afterward, they were followed up for 30 days. The 6 min walk test (6MWT), 36-Item Short Form Survey (SF-36, a quality-of-life questionnaire), WHO functional class (FC), and Borg dyspnea score (BDS) were used to indirectly assess exercise capacity. Blood samples were obtained before and after treatment and at the end of follow-up. <b>Results:</b> Walking distance in the 6MWT increased from 352.2 ± 114.8 m to 398.9.8 ± 128.5 m (<i>p</i> = 0.021) after meldonium. Meldonium treatment markedly improved WHO FC and SF-36 scores (<i>p</i> < 0.05). The drug significantly improved the BDS after the 6MWT (<i>p</i> = 0.003). Meldonium did not affect vital signs or blood biochemistry, including BNP. Meldonium treatment was safe in RVF patients. <b>Conclusions:</b> Meldonium treatment increases the functional capacity and overall well-being of RVF patients. Our results suggest that meldonium might be a viable novel drug for RVF treatment.