Myocardial bridge (MB): an angiographic curiosity?

The coronary angiograms of 1,500 cases performed between 1981 and 1989 were analysed to find out the incidence of Myocardial Bridge (MB) and its significance as regards myocardial ischemia. Sixteen of these (1.06%) were found to have MB. Their ages ranged from 27-70 years (m = 49.2) and male:female ratio was 13:3. Out of 16 patients, 7 (group A) had associated coronary artery disease (CAD) (7 of 1421; 0.49%) and remaining 9 (group B) had no associated CAD (9 of 79; 11.39%). All the MB were found on left anterior descending artery (LAD) (3 on proximal LAD and 13 on mid LAD). No MB was found on right coronary artery (RCA) or circumflex arteries. The location of the MB did not affect the pattern of CAD. Chronic stable angina was the commonest presenting symptom in group A patients (5 out of 7) and atypical angina in group B patients (5 out of 9). Majority of group B patients had either normal or nonspecific ST-T changes in ECG (7 out of 9). However, the presence of previous myocardial infarction or ECG evidence of 'Q' wave infarction (2 out of 2) was always associated with significant CAD. Similarly, regional wall motion abnormalities on echocardiogram were always found in patients with significant CAD and old myocardial infarction. All 9 patients with MB and normal coronary arteries were managed conservatively with good relief of symptoms, whereas other seven patients were managed on the merits of the underlying CAD. In conclusion, the MB is a normal variant found incidentally on coronary angiography, and does not have any definite clinical correlations or pathological significance.