Myocardial bridging in Taiwan: depiction by multidetector computed tomography coronary angiography.

Background/purpose: Myocardial bridging (MB) is a condition in which a segment of the major epicardial coronary artery is tunneled within and surrounded by the myocardium. This condition has been linked to severe complications. The aim of this study was to evaluate the incidence of MB in Taiwanese subjects examined with electrocardiogram-gated, 16-slice, multidetector computed tomography (MDCT) coronary angiography, as well as to determine the location, depth, and length of the bridged segments and the concomitant atherosclerosis of MB.

Methods: From August 2004 to May 2005, 276 consecutive subjects referred to our department for MDCT coronary angiography were enrolled in the study after written informed consent was obtained from each participant.

Results: Twenty-four subjects (8.7%) had at least one coronary segment that was completely surrounded by myocardium. Patients ranged in age from 27 to 76 years, with an average of 54 +/- 12 years. Thirty coronary segments were found to have MB. The most common location of MB was in segment 7, which accounted for 14 coronary segments (46.7%) of the total number of bridged segments; left anterior descending artery (LAD) segments accounted for 23 (76.7%); and right coronary artery and left circumflex artery segments accounted for three (10%) and two (6.7%), respectively. The length of bridged segments ranged from 5.2 to 50.6 mm, with an average length of 24.6 +/- 11.8 mm, and the depth of the bridged segments ranged from 0.5 to 9.1 mm, with an average depth of 3.65 +/- 1.89 mm. Two bridged segments (6.7%) had concomitant atherosclerosis; these were located in segment 7 (24.0 mm long and 6.10 mm deep) and segment 8 (27.1 mm long and 7.0 mm deep). Bridged segments with concomitant atherosclerosis were deeper, but not longer, compared with bridged segments without concomitant atherosclerosis (p < 0.05).

Conclusion: Electrocardiogram-gated MDCT is an effective noninvasive tool for evaluating MB in a clinical setting. The most common location of MB was in the LAD, especially in segment 7. Bridged segments with concomitant atherosclerosis were deeper, but not longer, compared with bridged segments without concomitant atherosclerosis.