Myocardial bridging increases the risk of coronary spasm.
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.
Teragawa
Hiroki
H
Department of Medicine and Molecular Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan. hteraga@hiroshima-u.ac.jp
Fukuda
Yukihiro
Y
Matsuda
Keiji
K
Hirao
Hidekazu
H
Higashi
Yukihito
Y
Yamagata
Togo
T
Oshima
Tetsuya
T
Matsuura
Hideo
H
Chayama
Kazuaki
K
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*
D014665:Vasodilator Agents; D005996:Nitroglycerin; D000109:Acetylcholine