Hemodynamic effect of iloprost inhalation and oral sildenafil during acute vasoreactivity test in pulmonary arterial hypertension.

BACKGROUND The vasoreactivity test is usually performed to identify pulmonary arterial hypertension (PAH) patients who may benefit from long-term calcium channel blocker (CCB). The first and most commonly used agent is intravenous epoprostenol. A few other agents such as intravenous adenosine and inhaled nitric oxide are also used. In Thailand, epoprostenol is not available and the others are costly. Therefore, inhaled iloprost or oral sildenafil may be alternatives to test vasoreactivity. OBJECTIVE To evaluate the hemodynamic effect and response rate of inhaled iloprost and oral sildenafil during acute vasoreactivity test in PAH patients. MATERIAL AND METHOD In this retrospective descriptive study, the authors recruited patients with idiopathic PAH (IPAH) or PAHassociated with connective tissue disease (PAH-CNT) seen at the Medicine department Siriraj Hospital between January 2005 and December 2011 for whom acute vasoreactivity test was indicated. All patients used 20 microgram of inhaled iloprost via Delphinus® nebulizer for the test. Hemodynamic parameters were recorded before and after iloprost administration. Eight of those patients subsequently had a repeated test using 100 mg of oral sildenafil. RESULTS Fifteen patients had acute vasoreactivity testing. Eleven patients were IPAH and four were PAH-CNT Using ESC/ERS guidelines criteria for responsiveness to vasoreactivity test, the response rate was 13% (2 out of 15 patients) using inhaled iloprost. Hemodynamic change was seen as early as five minutes after the inhalation and the effect lasted up to 35 minutes. The response rate was 25% (2 out of 8 patients) using oral sildenafil. Hemodynamic change was seen as early as 30 minutes after sildenafil ingestion and lasted up to 480 minutes. CONCLUSION Inhaled iloprost can be used for acute vasoreactivity test in Thailand. The hemodynamic parameters should be recorded immediately after iloprost inhalation. Oral sildenafil, however, is not a suitable agent for acute vasoreactivity test due to its extended effect.