Coronary myocardial bridge: an innocent bystander?

Measurements of myocardial bridges on computed tomography predict presence of clinical symptoms and outcomes of adverse heart events: a retrospective study in a large population from China

Background Clinical-radiological correlation of myocardial bridge (MB) remains unclear. Purpose To correlate clinical symptoms and outcomes of MBs with computed tomography (CT) coronary angiography findings. Material and Methods A total of 2092 patients with CT coronary angiography were collected. Patients were divided into symptomatic and asymptomatic groups, adverse heart events (AHE) and non-AHE groups, MB and non-MB groups, as well as left anterior descending (LAD)-MB and non-LAD-MB groups. Statistical analyses were performed to identify inter-group differences, and clinical-radiological correlations of MBs or mural coronary arteries (MCAs). Results The prevalence of MB, the MCA stenosis either in systole or in diastole, and the ratio of LAD-MB were significantly higher in the symptomatic group than in the asymptomatic group, and higher in the AHE group than in the non-AHE group ( P all <0.05). MB thickness, systolic MCA stenosis, and diastolic MCA stenosis were independent variables predicting clinical symptoms ( P < 0.05), with diastolic MCA stenosis having the highest diagnostic performance, when cutting at 24.6%. The corresponding sensitivity and specificity were 87.8% and 90.6%, respectively. Diastolic MCA stenosis independently indicated outcome of AHE (odds ratio, 1.047; P < 0.001). Conclusion Measurements of MB-MCA by CT predict the presence of clinical symptoms and outcomes of AHE, with diastolic MCA stenosis possessing the greatest performance.

Myocardial bridges: A review

Much has been written regarding the potential clinical significance of myocardial bridges. As such bridging is often seen in normal individuals, it is clear that not all arteries bridged by myocardial segments produce clinical symptoms thereby suggesting that this feature may simply be an anatomical variant. However, some authors who have considered these bridges as the cause of cardiac ischemia have suggested two potential mechanisms for their pathophysiology. The first is a phasic systolic compression of the bridged segment with persistent mid-to-late diastolic reduction in arterial diameter and the second proposes a reduction in arterial flow. Both mechanisms may contribute to a reduced reserve in coronary blood flow. In this review, we discuss the evidence that exists regarding myocardial bridging and the potential for bridging to cause myocardial ischemia.

Evaluation of myocardial bridges with optical coherence tomography

This study investigated the morphological characteristics of myocardial bridges (MBs) using optical coherence tomography (OCT) imaging compared with coronary artery angiography (CAG) and also evaluated atherosclerotic lesions in the proximal segments of MBs. Twelve patients (seven males, five females, age range 36 - 81 years) with MBs in the left anterior descending coronary artery were enrolled and examined. The mean +/- SD length of the MBs measured by OCT appeared significantly longer than when measured by CAG (20.5 +/- 4.2 mm versus 15.6 +/- 3.5 mm, respectively). The mean +/- SD maximal extent of MB stenosis appeared significantly smaller with OCT compared with CAG (48.7 +/- 4.8% versus 55.3 +/- 2.6%, respectively). Intimal thickening was observed only in the proximal 2 cm arterial segment of MBs. The morphological and intimal structure characteristics of MBs can be observed clearly with OCT.