Pulmonary arterial hypertension (PAH) is a rare condition characterized by an increase in pulmonary arterial resistance leading to right heart failure and death. Arrhythmias are a growing problem in PAH; therefore, maintenance of sinus rhythm is considered to be an important treatment aim in these patients. We described the case of a 46-year-old woman with HIV-associated pulmonary arterial hypertension who developed atrial flutter. After treatment with bosentan, it was observed a significant improvement in clinical and haemodynamic parameters. In addition, the AFL, which had previously persisted to both antiarrhythmic drug therapy and electrical stimulation, and had recurred after transthoracic electrical cardioversion, disappeared in absence of any antiarrhythmic drug. Though the precise factors responsible for supraventricular arrhythmogenesis are still largely obscure, it is likely that initiation and maintenance of AFL may depend on all the conditions that can lead to increase in right atrial pressure, size, and wall stress, such as PAH. In our case, bosentan reduced both mean pulmonary artery pressure (mPAP) value and right heart chambers pressures. Therefore, it is conceivable that with the anatomical substrate needed for the maintenance of AFL being disappeared, sinus rhythm was restored.