Objectives: In proximal chronic thromboembolic pulmonary hypertension, pulmonary endarterectomy is the treatment of first choice. In general, medical treatment before pulmonary endarterectomy is not indicated. However, selected "high-risk" patients might benefit by optimization of pulmonary hemodynamics. Moreover, in patients whose surgery is delayed owing to limited medical resources, pretreatment may prevent clinical deterioration. The primary objective of this study was to determine whether the dual endothelin-1 antagonist bosentan improves pulmonary hemodynamics and functional capacity in patients with proximal chronic thromboembolic pulmonary hypertension waiting for pulmonary endarterectomy.
Methods: We used an investigator-initiated, randomized, controlled single-blind study. Patients were randomized to receive bosentan (n = 13) or no bosentan (n = 12) for 16 weeks, next to "best standard of care." The primary end point was change in total pulmonary resistance. Secondary end points included changes in 6-minute walk distance, mean pulmonary artery pressure, and cardiac index.
Results: After 16 weeks, the mean differences in change from baseline between the groups were as follows: total pulmonary resistance 299 dynes x s x cm(-5) (P = .004), 6-minute walk distance 33 m (P = .014), mean pulmonary artery pressure 11 mm Hg (P = .005), and cardiac index 0.3 L x min(-1) x m(-2) (P = .08). Treatment with bosentan was safe. After pulmonary endarterectomy, 4 patients died (no-bosentan group: n = 3); the short-term in-hospital postoperative clinical course was similar in both groups of patients.
Conclusions: Patients with proximal chronic thromboembolic pulmonary hypertension may benefit hemodynamically and clinically from treatment with bosentan before pulmonary endarterectomy. Individual factors predictive of a beneficial response and whether this influences either morbidity or mortality associated with pulmonary endarterectomy remain to be established.
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