Clinical relevance of myocardial bridging severity: Single center experience

Background Myocardial bridging refers to intramyocardial systolic compression of a segment of an epicardial coronary artery. We aimed to identify the clinical significance of myocardial bridging by assessing the clinical presentation in non-obstructive coronary artery disease among a cohort of consecutive patients presenting for coronary angiography. Materials and methods A retrospective review of our institution's database between September 2002 and March 2005 was conducted to review coronary angiography reports of 14 416 patients. The study group included 226 patients (prevalence = 1·57%) with isolated myocardial bridging and < 50% stenosis in the non-bridged arteries. Cases with myocardial bridging were classified according to the percentage of systolic compression of the left anterior descending artery into group I (< 50% compression), group II (50-70% compression) and group III (compression ≥ 70%). Results Mean age was 57·6 ± 15·5 years; 59% were men. The mean duration of follow-up was 12 ± 2 months. The left anterior descending was the most common site of bridging (210, 93%). There was a significant difference between groups I and III with respect to the percentage of patients who presented with non-fatal myocardial infarction (P = 0·02). Unstable angina had the highest association with myocardial bridging, but there was no significance among the level of myocardial bridging severity and the clinical presentation of angina. Conclusions Myocardial bridging is not a benign variation of coronary anatomy. It is associated with angina and myocardial infarction in patients with ≥ 70% systolic compression. The bridged segment may be a cause of enhanced atherosclerotic plaque formation.