Left anterior descending coronary artery myocardial bridging by multislice computed tomography: correlation with clinical findings

Abstract

Objective: To assess the relationship between left anterior descending (LAD) coronary artery myocardial bridging detected by 64-slice computed tomography (CT) and clinical findings.

Methods: 221 consecutive patients were examined with coronary 64-slice CT angiography. 21 patients with coronary stenosis >50% were excluded. The length, depth, and luminal narrowing of LAD myocardial bridges during systole and diastole were measured. CT findings were compared with the treadmill ECG-stress test, and clinical symptoms.

Results: Myocardial bridges of the LAD were found in 23% of patients (51/221) (length, 14.9+/-6.5mm; depth, 2.6+/-1.6mm). A significant difference was noted between the LAD luminal diameter before the intramyocardial course and intramyocardially, for both diastole and systole (p<0.001); with a higher diameter reduction of 27% for end-systole compared to end-diastole with 15% (p=0.006). Systolic LAD intramyocardial luminal narrowing >50% was found in 3/25 (8%). 30/51 (59%) of bridges were "deep" (>2mm myocardial depth), 21/51 (41%) were "superficial". The prevalence of a positive ECG-stress tests for the anterior myocardial region was significantly higher in patients with LAD myocardial bridges (34/50; 68%) compared to those without (28/144; 19.4%) (p<0.001). There was no difference between "superficial" and "deep" LAD myocardial bridges in regard to a positive treadmill ECG-stress test. Typical angina was rare with 6%.

Conclusion: LAD myocardial bridges are common findings and can possibly explain a positive exercise ECG-stress test for anterior myocardial ischemia. Intramyocardial LAD segments show mild-to-moderate luminal narrowing at rest, which is higher during end-systolic phase.