Safety of Adenosine for Acute Pulmonary Vasoreactivity Testing in Pulmonary Hypertension

Background: Acute pulmonary vasoreactivity testing (APVT) is performed during right heart catheterization (RHC) in patients with pulmonary arterial hypertension (PAH) to identify those who may benefit from long-term calcium channel blocker (CCB) therapy. Inhaled nitric oxide (iNO) is the most commonly used agent. However, a few other agents such as intravenous (i.v.) epoprostenol or i.v. adenosine can also be used. At present, intravenous prostaglandins and iNO are expensive and not-easily available in most Iranian medical facilities. Indeed intravenous adenosine is less expensive and available in all hospital settings. Objectives: We aimed to investigate the safety profile of adenosine in a group of Iranian PAH patients undergoing APVT. Methods: In this prospective study, a total of 57 consecutive patients with PAH who were scheduled to undergo RHC were enrolled. Acute reactivity testing was performed in 56 patients. Results: Twenty (36%) patients had positive APVT. In all cases, adenosine administration was limited by the occurrence of drug-induced minor side effects including chest pressure or tightness, flushing and dyspnea. The maximal tolerated dose of adenosine was 225 ± 25 µg/kh/min (range 200 - 300µg/kh/min) in the study population. Only 2 patients developed atrioventricular block at doses of 100µg/kh/min and 150µg/kh/min, respectively. Both patients spontaneously converted to sinus rhythm within one minute of discontinuation of adenosine infusion. Conclusions: Intravenous adenosine can be safely used for APVT in Iran.