Abstract 3270: Atherosclerosis and Myocardial Bridging: Noninvasive Evaluation with 64 Slice Multidetector Computed Tomographic Angiography
Background: Myocardial bridging (MB) is most commonly localized in the middle segment of the left anterior descending coronary artery (LAD). The clinical significance is thought to be related to the degree of systolic arterial compression. Scant pathologic data suggest that MB is associated with the development of atherosclerosis proximal to the tunneled portion of the artery, and that the bridged area is protected from atherosclerosis; there are no clinical studies. Multidetector computed tomographic coronary angiography (MDCTA) is ideally suited to address these issues.
Methods: 300 consecutive 64 slice MDCTA were evaluated retrospectively; 55 patients with bypass surgery, or poor quality studies were excluded. The axial and multiplanar reformatted images were analyzed for the presence of obstructive CAD (>25% stenosis), nonobstructive calcified and noncalcified plaque in all vessels, and for MB in the LAD. MB was defined as a segment partially or completely surrounded by myocardium. Patients were divided based on the presence (Group1) or absence (Group2) of MB.
Results: MB was present in 44% of patients; the middle LAD was the most common segment involved (65%). There were no significant differences in age, sex or presence of any CAD. The prevalence of obstructive and nonobstructive CAD in the proximal, middle or distal LAD segments was similar in both groups. There were neither obstructive nor nonobstructive plaques within the MB segments.
Conclusions: This is the first noninvasive clinical evaluation of MB, and demonstrates that:
The presence of MB was not associated with increased CAD in the LAD segments proximal to the MB.
The MB segment was totally devoid of obstructive and nonobstructive CAD.
This striking finding suggests a fertile area for research into the genesis of atherosclerosis and possible protective mechanisms.