Implications of Myocardial Bridge on Coronary Atherosclerosis and Survival

Background: In this study, we aimed to describe the impact of MBs on atherosclerosis and survival, in patients with coronary artery disease (CAD). Methods: We retrospectively studied 1920 consecutive patients who underwent conventional coronary angiography for suspected CAD. Atherosclerotic load (AL), defined as the sum of degrees of stenosis, and general atherosclerotic load (GAL), representing the sum of AL, were compared between patients with MB and a control group without MB; patients in these groups were similar in age and sex. We assessed survival at 10 years after the last enrolled patient. Results: Prevalence of MB was 3.96%, predominantly in the mid-segment of left anterior descendent artery (LAD). In the presence of MB, GAL was lower (158.1 +/- 93.7 vs. 205.3 +/- 117.9, p = 0.004) with a lesser AL in the proximal (30.3 +/- 39.9 vs. 42.9 +/- 41.1, p = 0.038) and mid-segments (8.1 +/- 20.0 vs. 25.3 +/- 35.9, p < 0.001) of LAD. Based on a Multinominal Logistic Regression, we found that the presence of MB on LAD (regardless of its location on this artery) is a protective factor against atherosclerotic lesions, decreasing the probability of significant stenosis, especially of those >= 70%, on the entire artery (B -1.539, OR 4660; 95% CI = 1.873-11.595, p = 0.001) and on each of its segments as well: proximal LAD (B -1.275, OR 0.280; 95% CI = 0.015-5.073; p = 0.038), mid-LAD (B -1.879, OR 6.545; 95% CI = 1.492-28.712; p = 0.013) and distal LAD (B -0.900, OR 2.459, 95% CI = 2.459-2.459, p = 0.032). However, 10-year survival was similar between groups (76.70% vs. 74.30%, p = 0.740). Conclusion: The presence of MB on LAD proved to be a protective factor against atherosclerosis for the entire artery and for each of its segments, but it does not influence long-term survival in patients with CAD.