[Myocardial bridge of the left anterior descending coronary artery and myocardial infarction: does coronary spasm play a part?].

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.