OBJECTIVETo investigate the clinical features of coronary artery spasm patients with or without myocardial bridge and explore the roles of endothelial dysfunction in these patients.

METHODSOne hundred eighteen patients undergone acetylcholine provoking test were divided into myocardial bridge (MB) group (n = 26) and non-myocardial bridge (NMB) group (n = 92). The results of acetylcholine test, treadmill exercise electrocardiography, stress myocardial perfusion scintigraphy, plasma level of endothelin-1 and nitric oxide were compared between MB group and NMB group.

RESULTSCoronary artery spasm was induced in 21 patients in MB group (81%) and 52 patients in NMB group (57%, P < 0.05). Positive treadmill electrocardiography was obtained in 19 patients in MB group (73%) and 7 patients in NMB group (8%, P < 0.001). Ischemic perfusion defect in 20 (77%) and 9 patients (10%, P < 0.001) and reverse redistribution in 23 (88%) and 68 patients (74%, P > 0.05). Patients showed different clinical features in MB group and NMB group (more short-duration exertional angina and could not be readily released by nitroglycerine in MB group while more patients experienced long-lasting variant angina and symptoms could be readily released by nitroglycerine). Plasma endothelin-1 level was significantly higher [(132.1 +/- 6.5) ng/L vs. (108.5 +/- 8.2) ng/L, P < 0.01] while nitric oxide was significant lower [(84.7 +/- 17.5) ng/L vs. (99.8 +/- 18.2) ng/L, P < 0.05] in MB group compared to NMB group.

CONCLUSIONMB patients were prone to coronary artery spasm partly due to endothelial dysfunction. Patients with MB and coronary artery spasm also showed classic clinical symptoms and positive stress tests for ischemia.