The association of a myocardial bridge of the left anterior descending (LAD) coronary artery and
myocardial infarction is rare. The mechanisms by which the myocardial bridge could predispose to
myocardial infarction are
tachycardia (reducing the duration of diastolic coronary filling),
thrombosis at the site of the myocardial bridge, and coronary
spasm which, however, has never been demonstrated in the context of
infarction. The aim of this study was to detect coronary
spasm by provocative
ergometrine testing in 4 patients, all male, aged 21 to 49 years, average 39 years old, who had anterior
myocardial infarction associated with
myocardial bridging of the LAD artery without atheromatous
coronary stenosis. The
ergometrine tests were performed during (2 cases) or after coronary angiography (2 cases). The systolic narrowing due to the myocardial bridge ranged from 25 to 95% (average 70%). The
ergometrine test was strongly positive in 1 patient and negative in the other 3. Repermeabilisation of a
thrombus was suggested in these 3 patients by the recording of an accelerated idioventricular rythm in the acute phase of
infarction (2 cases) or by the demonstration of abnormal platelet aggregation (1 case). This is the first report of coronary
spasm in a patient with
myocardial bridging associated with
infarction. However, it is not possible to determine the respective roles of
spasm and
myocardial bridging in the genesis of the
infarct. We suggest systemic provocative
ergometrine testing in this situation to orientate the most appropriate treatment.