Adenosine is a nucleoside that impacts the cardiovascular system via the activation of its membrane receptors, named A1R, A2AR, A2BR and A3R. Adenosine is released during hypoxia, ischemia, beta-adrenergic stimulation or inflammation and impacts heart rhythm and produces strong vasodilation in the systemic, coronary or pulmonary vascular system. This review summarizes the main role of adenosine on the cardiovascular system in several diseases and conditions. Adenosine release participates directly in the pathophysiology of atrial fibrillation and neurohumoral syncope. Adenosine has a key role in the adaptive response in pulmonary hypertension and heart failure, with the most relevant effects being slowing of heart rhythm, coronary vasodilation and decreasing blood pressure. In other conditions, such as altitude or apnea-induced hypoxia, obstructive sleep apnea, or systemic hypertension, the adenosinergic system activation appears in a context of an adaptive response. Due to its short half-life, adenosine allows very rapid adaptation of the cardiovascular system. Finally, the effects of adenosine on the cardiovascular system are sometimes beneficial and other times harmful. Future research should aim to develop modulating agents of adenosine receptors to slow down or conversely amplify the adenosinergic response according to the occurrence of different pathologic conditions.

Development of direct-acting antiviral agents against hepatitis C virus (HCV) has changed the management of chronic HCV infection. We report three cases of newly diagnosed or exacerbated pulmonary arterial hypertension (PAH) in patients treated with sofosbuvir. All patients had PAH-associated comorbidities (HIV coinfection in two, portal hypertension in one) and one was already being treated for PAH. At admission, all patients presented with syncope, World Health Organization functional class IV, right-sided heart failure, and extremely severe hemodynamic parameters. After specific PAH therapy, the clinical and hemodynamic properties for all patients were improved. Severity and acuteness of PAH, as well as chronology, could suggest a causal link between HCV treatment and PAH onset. We hypothesize that suppression of HCV replication promotes a decrease in vasodilatory inflammatory mediators leading to worsening of underlying PAH. The current report suggests that sofosbuvir-based therapy may be associated with severe PAH.