Manifestations of (superscript 201)Tl Myocardial Single Photon Emission Computed Tomography in Patients with Myocardial Bridge

Background: Myocardial bridge (MB) is an congenital coronary anomaly resulting in systolic narrowing of coronary artery. It may be seen occasionally during coronary angiography (CAG) examinations and may cause clinical symptoms and/or signs of coronary artery disease (CAD). The symptoms/signs include angina pectoris, myocardial infarction, vasospasm, cardiac arrythmia, and sudden cardiac death. Few previous reports stated about the (superscript 201)TI perfusion defects noted in patients with MB, which probably imply the evidence of myocardial ischemia. The purpose of this study is to do a retrospective analysis of (superscript 201)TI images in patients with MB. Methods: From July, 2000 to June, 2003, 63 patients (30 male; mean age 57±10, and range from 33 to 80 years old), with chest pain and/or chest tightness underwent stress test for CAD. Six patients underwent treadmill exercise with Bruce protocol and 57 patients received dipyridamole as pharmacological stress. All patients were followed by image acquisitions done immediately after stress and 4 h later. All underwent CAG subsequently to identify the severity of CAD. Results: In all of the 63 patients, CAG revealed MB. Fifty patients had MB in left descending artery (LAD) (40 at mid portion; 8 at distal portion; 2 at mid and distal portion), 4 in left circumflex artery (LCX), and 1 in right coronary artery (RCA). Seven patients had MB in both LAD and LCX, and 1 patient had MB in both LAD and RCA. Sixty patients (95%) had (superscript 201)TI perfusion defects in either reverse (R), partial reverse (PR), or reverse redistribution (RR) patterns. In the abnormal (superscript 201)TI SPECTs, 103 abnormal perfusion areas were found including 57 R (55%), 40 PR (39%), and 6 RR (6%). In all vessels with MB, 48 (83%) in LAD could see (superscript 201)TI perfusion defects in anterior, septal, and/or apical areas. In addition, 6 of 11 (55%) in LCX could detect defects in lateral or inferior areas, and 2 of 2 (100%) in RCA could detect defects in inferior areas. Conclusions: Myocardial ischemia with abnormal (superscript 201)TI perfusion image can be detected in most patients with MB. MB with ischemic evidence in (superscript 201)TI perfusion image also may be associated with chest pain and/or chest tightness in our patients. (superscript 201)TI perfusion defect may be presented with R, PR, or RR in patients with MB. The significance of three different perfusion defects patterns (R, PR, and RR) may represent the various severity of perfusion insufficiency induced by MB.