title: Myocardial bridging increases the risk of coronary spasm.
abstract: BACKGROUND
  Myocardial bridging (MB) has been associated with cardiac events. Whether coronary spasm is one factor contributing to those events is unknown.
  
  
  OBJECTIVE
  This study investigated whether the likelihood of coronary spasm is increased in patients with MB.
  
  
  METHODS
  A spasm-provocation test was performed by infusing acetylcholine into the left coronary artery in 114 Japanese patients with chest pain. The test result was defined as positive when the diameter of the coronary artery was reduced by > or = 50% and ST-segment changes were documented. Myocardial bridging was defined as a > 15% reduction in coronary arterial diameter during systole after intracoronary injection of nitroglycerin.
  
  
  RESULTS
  Myocardial bridging was identified in 41 patients (36%) and was located in the mid-segment of the left anterior descending coronary artery (LAD) in all patients. Patients with MB experienced coronary spasm more frequently than patients without MB (MB+: 73%; MB-: 40%, p = 0.0006). Furthermore, among patients with a positive spasm-provocation test, coronary spasm occurred more frequently in the mid-segment of the LAD in patients with MB than in those without MB (MB+: 73%; MB-: 45%, p = 0.0259). Multivariate regression analysis demonstrated that MB was a predictor of coronary spasm (odds ratio: 3.478, p = 0.0088).
  
  
  CONCLUSIONS
  These results suggest that MB increases the risk of coronary spasm and that coronary spasm may be the proximate etiology of cardiac events associated with MB.
authors.affiliation: Department of Medicine and Molecular Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan. hteraga@hiroshima-u.ac.jp
authors.forename: Hiroki
authors.initials: H
authors.lastname: Teragawa
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Fukuda
authors.forename: Keiji
authors.initials: K
authors.lastname: Matsuda
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Hirao
authors.forename: Yukihito
authors.initials: Y
authors.lastname: Higashi
authors.forename: Togo
authors.initials: T
authors.lastname: Yamagata
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Oshima
authors.forename: Hideo
authors.initials: H
authors.lastname: Matsuura
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Chayama
mesh_terms: D000109:Acetylcholine / Q000008:administration & dosage / Q000494:pharmacology*; D000787:Angina Pectoris / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy; D001158:Arteries / Q000187:drug effects; D017023:Coronary Angiography; D003329:Coronary Vasospasm / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology; D003331:Coronary Vessels / Q000187:drug effects*; D005260:Female; D006801:Humans; D007269:Injections, Intra-Arterial; D008297:Male; D008875:Middle Aged; D005996:Nitroglycerin / Q000008:administration & dosage*; D011237:Predictive Value of Tests; D012307:Risk Factors; D014463:Ultrasonography; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D005996:Nitroglycerin; D000109:Acetylcholine