Changes in Exercise Capacity and Cardiac Performance in a Series of Patients with Eisenmenger's Syndrome Transitioned from Selective to Dual Endothelin Receptor Antagonist

Background: Differences in clinical effects between selective and dual endothelin (ET) receptor antagonists (ERA) in patients with pulmonary arterial hypertension (PAH) are currently unknown. We aimed to assess prospectively how transition from selective (sitaxsentan) to dual (bosentan) ERA affected exercise capacity and cardiocirculatory performance in patients with Eisenmenger's syndrome. Methods: A series of seven stable patients with Eisenmenger's syndrome aged 40.0 (30.0-56.0) years old treated with sitaxsentan were assessed before and three months after transition to bosentan. Six minute walk test and magnetic resonance to assess LV and RV mass, volume and ejection fraction, and pulmonary flow, and laboratory tests were performed. Results: We observed an increase in LV mass [96.5 (66.0-116.0) vs. 123.0 (93.0-146.0) g; p = 0.03], LV ejection fraction [55.0 (44.0-63.0) vs. 65.0 (58.0-70.0)%; p = 0.02)], and pulmonary flow [64 (53.0-71.0) vs. 69.0 (55.0-84.0) ml/beat; p = 0.046]. This was accompanied by an increase of oxygen saturation, elongation of 6MWD [435.0 (378.0-482.3) vs. 474 (405.0-534.7); p = 0.02], decrease of NTproBNP level and increase of ET-1 level. Conclusions: Three month follow-up of stable patients with Eisenmenger's syndrome transitioned from sitaxsentan to bosentan revealed improvement of exercise capacity despite significant elevation of ET-1 level. Concurrent increase of LV ejection fraction and pulmonary flow might have contributed to these favourable effects. (Heart, Lung and Circulation 2012;21:671-678) (C) 2012 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier Inc. All rights reserved.