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.

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 >or= 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 >or= 70% systolic compression. The bridged segment may be a cause of enhanced atherosclerotic plaque formation.