A myocardial bridge(MB) is an anatomical arrangement in which an epicardial coronary artery becomes engulfed for a limited segment by myocardial fibers. Although it has generally been felt that most instance of bridge are benign. Recent reports have suggested that MB can be associated with evidence of myocardial ischemia, myocardial infarction, arrhythmia and sudden death. This study investigated clinical characteristics of myocardial bridge and significance of treadmill test(TMT).

Among 4317 consecutive coronary angiograms performed from November 1995 to June 1999, 52 patients had a myocardial bridge. For the patients with MB, the clinical data, coronary angiography and the results of treadmill tests were reviewed.

The overall prevalence of myocardial bridge was 1.22%. Stable angina, atypical chest pain, variant angina, AMI were 33(63%), 15(29%), 2(4%), 2(%) cases, respectively. Electrocardiographic finding were normal in 31 cases(59%), ST-T change in 20 cases(38%), OMI in 1 case(3%). Mean systolic stenosis of MB was 54%, Mean length of segment of MB was 11.96 4.96mm and all patients had MBs of left anterior descending(LAD) coronary artery. Among 23 cases which had been performed TMT, 17 were positive(77%). There was no significant statistical difference between TMT(+) and TMT(-) in clinical characteristic and coronary angiographic data. We divided the patients with MB into two groups [group I(34 cases): systolic compression < 50%(mean 35.1 10.7%), group II(18 cases): systolic compression 50%(mean 63.6 14.7%)] and there were no statistical difference in clinical characteristics, TMT and angiographic data.

The patients with MB present variable clinical characteristics of stable angina, atypical chest pain, variant angina, acute myocardial infarction. There is no relationship between the degree of systolic compression and TMT positive in MB. We think that symptoms of MB are not developed only by mechanical compression but concerned with other variable mechanism.