Atherosclerotic pattern of coronary myocardial bridging assessed with CT coronary angiography

The aim of our study was to evaluate the atherosclerotic pattern of patients with coronary myocardial bridging (MB) by means of CT Coronary Angiography (CT-CA). 254 consecutive patients (166 male, mean age 58.6 ± 10.3) who underwent 64-slice CT-CA according to current clinical indications were reviewed for the presence of MB and concomitant segmental atherosclerotic pattern. Coronary plaques were assessed in all patients enrolled. 73 patients (29%) presented single (90%) or multiple (10%) MB, frequently (93%) localized in the mid-distal left anterior descending artery. The MB segment was always free of atherosclerosis. Segments proximal to the MB presented: no atherosclerotic disease (n = 37), positive remodeling (n = 23), 50% stenoses (n = 7). Distal segments presented a different atherosclerosis pattern (P < 0.0001): absence of disease (n = 73), no significant lesions (n = 8). No significant differences were found between segments proximal to MB and proximal coronary segments apart from left main trunk. Pattern of atherosclerotic lesions located in segments 6 and 7 significantly differs between patients with MB and patients without MB (P < 0.05). CT-CA is a reliable method to non-invasively demonstrate MB and related atherosclerotic pattern. CT-CA provides new insight regarding atherosclerosis distribution in segments close to MB

Could increased axial wall stress be responsible for the development of atheroma in the proximal segment of myocardial bridges?

<p>Abstract</p> <p>Background</p> <p>A recent model describing the mechanical interaction between a stenosis and the vessel wall has shown that axial wall stress can considerably increase in the region immediately proximal to the stenosis during the (forward) flow phases, so that abnormal biological processes and wall damages are likely to be induced in that region. Our objective was to examine what this model predicts when applied to myocardial bridges.</p> <p>Method</p> <p>The model was adapted to the hemodynamic particularities of myocardial bridges and used to estimate by means of a numerical example the cyclic increase in axial wall stress in the vessel segment proximal to the bridge. The consistence of the results with reported observations on the presence of atheroma in the proximal, tunneled, and distal vessel segments of bridged coronary arteries was also examined.</p> <p>Results</p> <p>1) Axial wall stress can markedly increase in the entrance region of the bridge during the cardiac cycle. 2) This is consistent with reported observations showing that this region is particularly prone to atherosclerosis.</p> <p>Conclusion</p> <p>The proposed mechanical explanation of atherosclerosis in bridged coronary arteries indicates that angioplasty and other similar interventions will not stop the development of atherosclerosis at the bridge entrance and in the proximal epicardial segment if the decrease of the lumen of the tunneled segment during systole is not considerably reduced.</p