Myocardial bridging of the coronary arteries.

Of 1102 consecutive coronary angiograms 16 (1.4%) were found to have systolic narrowing typical of myocardial bridging on the left anterior coronary artery or its branches. Four cases of bridging had otherwise normal coronary arteriograms, four were associated with left ventricular hypertrophy (three in cases of aortic valve disease and one case of hypertrophic cardiomyopathy) and eight were found in association with fixed coronary artery stenoses. Bridging was seen more commonly than expected on normal angiograms. When bridging was associated with left ventricular hypertrophy it affected a longer segment and caused more severe compression. When bridging was found in patients with coronary artery disease, it was not associated with atheroma at its site. Evidence for a pathogenic role of myocardial bridging in ischaemic heart disease is discussed.