Improved myocardial perfusion preceding clinical response on bosentan treatment for coronary vasospasm.

Many patients suffer from persistent angina due to coronary vasospasm despite optimal medical treatment. We treated a 46-year-old patient with severe and treatment-resistant coronary vasospasm with the endothelin-receptor antagonist bosentan. Using oxygen-15-labelled water in conjunction with oxygen 15-labelled carbon monoxide positron emission tomography (PET), we measured an impaired coronary flow reserve (CFR) in 6 out of 13 segments directly before the start of bosentan therapy. A repeated PET measurement after 16 weeks of bosentan revealed a completely normalized CFR in this patient. Furthermore, the patient reported less frequent and less severe chest pain. Our data suggest a potential role of endothelin-receptor antagonists for patients with severe coronary vasospasms.