OBJECTIVETo investigate long-term efficacy and safety of ambrisentan monotherapy in patients with pulmonary arterial hypertension (PAH).

METHODSPatients with PAH who received 2.5 mg or 5 mg of ambrisentan once daily between July 10, 2011 and August 30, 2012 for at least 6 months were enrolled. The efficacy endpoints were change in exercise capacity, World Health Organization (WHO) functional class and N-terminal pro-brain natriuretic peptide (NT-proBNP) level, echocardiographic parameters. The safety endpoint was the safety of long-term ambrisentan administration, as defined by the incidence and severity of adverse events.

RESULTSA total of 18 patients with PAH were enrolled. Mean age was (39 ± 17) years, 8 (55.6%) were female, and 11 (61.1%) patients were in WHO functional class III. The median duration of treatment was 17 months (range: 6-26 months). After treatment, the 6MWD was significantly increased[ (495 ± 97) m vs. (400 ± 91) m, P < 0.001], NT-proBNP was significantly reduced [308 (53-1 645) ng/L vs. 80(22-454) ng/L, P = 0.005], the systolic pulmonary artery was significantly decreased [(62 ± 30) mmHg vs. (82 ± 41) mmHg, P = 0.001] and left ventricular end diastolic diameter was significantly increased [(44 ± 6) mm vs. (40 ± 6) mm, P < 0.004] compared to pre-treatment. WHO functional class was improved compared with baseline in 11(61.1%) patients, stable in 7(38.9%) patients. No patient died during the treatment period. No patient was withdrawn from this study for safety reasons.

CONCLUSIONSLong-term treatment of ambrisentan can effectively improve the exercise capacity, reduce systolic pulmonary artery pressure and NT-proBNP in PAH patients. Ambrisentan is safe and well tolerated in Chinese PAH patients.