Update review on myocardial bridging: New insights

Morphological analysis of myocardial bridging leading to myocardial ischemia: myocardial coronary coupling

Introduction

Myocardial bridge (MB) is a segment of an otherwise extramyocardial blood vessel that traverses the myocardium. This congenital condition typically lacks obvious clinical manifestations during adolescence. However, as individuals age, the accumulated myocardial pressure on the coronary arteries can lead to non-obstructive coronary ischemia, angina pectoris, and even heart failure. Early diagnosis is crucial for assessing the risk of cardiovascular events.

Methods

This study performed a morphological analysis of MB in 75 patients using dual-source Computed Tomographic Angiography (CTA). Through geometric three-dimensional reconstruction, measurements and statistical analyses were conducted on muscle bridge length, depth, length-to-depth ratio, cross-sectional area, and coronary artery curvature.

Results

This study explores the morphological differences among normal individuals, those with superficial MB, and those with deep MB during diastole and systole under varying conditions of myocardial coronary coupling. The study found that the compression degree is greatest in the deep MB group, with the average compression level being approximately 17 times that of normal individuals and about 4.6 times that of patients with superficial MB.

Discussion

The differences in the average cross-sectional area are more significant than those in the minimum cross-sectional area. The depth of the MB is more closely related to the degree of compression, suggesting that clinical intervention and attention should be focused on deep MBs.

Myocardial Bridging, Unusual Cause of Myocardial Infarction; Case Report and Review of Literature

Myocardial bridging is a common coronary anomaly. Although it is considered to be a benign condition, it can rarely be complicated by myocardial infarction. Clinicians should be suspicious of myocardial bridging as an etiology of myocardial infarction when other more common etiologies have been excluded. High resolution CT angiography is the gold standard for diagnostic evaluation, with the length and depth of the bridge, and response to conservative therapies guiding clinical decision making on surgical correction. Myocardial bridging is a congenital coronary anomaly in which the coronary arteries pass through the heart muscle rather than lying on its surface. It is typically a benign condition, and most patients are asymptomatic. However, some may experience symptoms of angina. In rare cases, patients can present with myocardial ischemia or infarction. In this report, we present the case of a 38-year-old female who presented with a 2-month history of chest pain. Further evaluation with coronary computed tomography angiography (CCTA) revealed myocardial bridging. Subsequently, she developed a myocardial infarction, a rare complication of this condition. We discuss this uncommon complication of a common anomaly.

Coronary CTA-based vascular radiomics predicts atherosclerosis development proximal to LAD myocardial bridging

AIMS

Cardiac cycle morphological changes can accelerate plaque growth proximal to myocardial bridging (MB) in the left anterior descending artery (LAD). To assess coronary computed tomography angiography (CCTA)-based vascular radiomics for predicting proximal plaque development in LAD MB.

METHODS AND RESULTS

Patients with repeated CCTA scans showing LAD MB without proximal plaque in index CCTA were included from Jinling Hospital as a development set. They were divided into training and internal testing in an 8:2 ratio. Patients from four other tertiary hospitals were set as external validation set. The endpoint was proximal plaque development of LAD MB in follow-up CCTA. Four vascular radiomics models were built: MB centreline (MB CL), proximal MB CL (pMB CL), MB cross-section (MB CS), and proximal MB CS (pMB CS), whose performances were evaluated using area under the receiver operating characteristic curve (AUC), integrated discrimination improvement (IDI), and net reclassification improvement (NRI). In total, 295 patients were included in the development (n = 192; median age, 54 ± 11 years; 137 men) and external validation sets (n = 103; median age, 57 ± 9 years; 57 men). The pMB CS vascular radiomics model exhibited higher AUCs in training, internal test, and external sets (AUC = 0.78, 0.75, 0.75) than the clinical and anatomical model (all P < 0.05). Integration of the pMB CS vascular radiomics model significantly raised the AUC of the clinical and anatomical model from 0.56 to 0.75 (P = 0.002), along with enhanced NRI [0.76 (0.37-1.14), P < 0.001] and IDI [0.17 (0.07-0.26), P < 0.001] in the external validation set.

CONCLUSION

The CCTA-based pMB CS vascular radiomics model can predict plaque development in LAD MB.

Myocardial ischemia caused by the synergistic effect of myocardial bridge and moderate stenosis: case report

BACKGROUND

Clinical events such as angina pectoris, acute coronary syndrome, and sudden death caused by myocardial bridge (MB) have attracted increasing attention. It is still a challenge to diagnose whether MB can cause the symptoms of patients with MB. For most MB patients, medication remains the primary treatment.

CASE PRESENTATION

This article reports a case of chest pain in a patient with MB in the middle segment of the left anterior descending artery (LADm) with moderate stenosis in the proximal segment (LADp). Through functional assessment, we found that neither MB nor fixed stenosis had sufficient effect on coronary blood flow to cause myocardial ischemia, but their synergistic effect resulted in myocardial ischemia. Finally, a stent was implanted in LADp and good clinical results were achieved.

CONCLUSIONS

For symptomatic patients with MB combined with fixed stenosis, functional evaluation may be necessary, which has significant guiding significance for treatment strategy selection. For asymptomatic patients, early detection of myocardial ischemia may also improve the prognosis of patients.

Robotic Totally Endoscopic Off-Pump Unroofing of Myocardial Bridge: Early Experience and Midterm Outcomes

OBJECTIVE

Myocardial bridging (MB) occurs when a coronary artery, commonly the left anterior descending (LAD), has an intramyocardial course. In symptomatic patients who fail medical therapy, surgical unroofing can provide symptomatic relief by improving coronary blood flow. We present a series of patients undergoing robotic totally endoscopic beating-heart MB unroofing.

METHODS

There were 34 patients with an LAD-MB who failed medical therapy and underwent robotic totally endoscopic, off-pump unroofing between January 2017 and October 2023. Patients were evaluated by a multidisciplinary team and underwent provocative coronary angiography to confirm hemodynamic significance. We reviewed perioperative outcomes and contacted patients for midterm follow-up, including completion of a modified Seattle Angina Questionnaire (SAQ).

RESULTS

The mean age was 48 ± 8 years, and 56% were female patients. One patient had prior septal myectomy via sternotomy. All patients had significant dobutamine Pd/Pa reduction on preoperative coronary angiography. One patient had atrial fibrillation and underwent concomitant ablation with left atrial appendage ligation. The mean procedure time was 140 ± 69 min. All were completed totally endoscopically off-pump without intraoperative conversions. The mean MB length was 4.5 ± 1.4 cm, and the mean depth was 1.6 ± 0.9 cm. Of the patients, 76% were extubated in the operating room. The mean intensive care unit and hospital length of stay were 0.97 ± 0.58 and 1.73 ± 1.1 days, respectively. There were no mortalities or strokes. There was 1 postoperative take-back for bleeding. At midterm follow-up (19 ± 14 months), 28 patients completed the SAQ; 86% reported "much less angina" during activity compared with before surgery, and 93% reported taking no antianginal medication since surgery.

CONCLUSIONS

In appropriate patients with hemodynamically significant LAD-MB who fail medical therapy, robotic beating-heart unroofing is possible with good outcomes. Further studies are warranted.

Myocardial Bridging Increases the Risk of Adverse Cardiovascular Events in Patients without Coronary Atherosclerosis

Background: Myocardial bridging (MB) is a congenital coronary anomaly and an important cause of chest pain. The long-term effects of MB on cardiovascular events remain elusive. Methods: We used the National Health Insurance Research Database of Taiwan to conduct an analysis. All patients who had undergone coronary angiography were considered for inclusion. The primary endpoint was a composite of nonfatal myocardial infarction, nonfatal ischemic stroke, and cardiovascular death. Results: We identified 10,749 patients from 2008 to 2018 and matched them with an equal number of controls by propensity-score matching. The mean follow-up period was 5.78 years. In patients without coronary artery disease, MB increased the risk of the composite endpoint (hazard ratio [HR]: 1.57, 95% confidence interval [CI]: 1.44-1.72, p < 0.001), which was driven by increased risks of nonfatal myocardial infarction and cardiovascular death. In patients with significant coronary artery disease, MB did not increase the risk of major adverse cardiovascular events. MB was identical to insignificant coronary artery disease from the viewpoint of clinical outcomes. Conclusions: The presence of MB significantly increases cardiovascular risks in patients with normal coronary vessels. Atherosclerotic coronary artery disease mitigates the effect of MB on cardiovascular outcomes. MB can be considered an insignificant coronary artery disease equivalent.

Quantitative computed tomography angiography evaluation of the coronary fractional flow reserve in patients with left anterior descending artery myocardial bridging

PURPOSE

To quantitatively investigate the effect of myocardial bridge (MB) in the left anterior descending artery (LAD) on the fractional flow reserve (FFR).

MATERIALS AND METHODS

Three-hundred patients with LAD MB who had undergone coronary artery CT angiography (CCTA) were retrospectively enroled, and 104 normal patients were enroled as the control. The CCTA-derived fractional flow reserve (FFRCT) was measured at the LAD 10 mm proximal (FFR1) and 20-40 mm distal (FFR3) to the MB and at the MB location (FFR2).

RESULTS

FFR2 and FFR3 of the MB (with BM only) and MBLA (with both MB and atherosclerosis) groups were significantly (p < 0.01) lower than those of the control. The FFR3 distal to the MB was significantly lower (p < 0.01) than that of the control. The FFRCT of the whole LAD in the MBLA group was significantly (p < 0.05) lower than that of the MB and control group (p < 0.05). MB length (OR 1.061) and MB muscle index (odds ratio or OR 1.007) were two risk factors for abnormal FFRCT, and MB length was a significant independent risk factor for abnormal FFRCT (OR = 1.077). LAD stenosis degree was a risk factor for abnormal FFRCT values (OR 3.301, 95% confidence interval [CI] 1.441-7.562, p = 0.005) and was also a significant independent risk factor (OR = 3.369, 95% CI: 1.392-8.152; p = 0.007) for abnormal FFRCT.

CONCLUSION

MB significantly affects the FFRCT of distal coronary artery. For patients with MB without atherosclerosis, the MB length is a risk factor significantly affecting FFRCT, and for patients with MB accompanied by atherosclerosis, LAD stenotic severity is an independent risk factor for FFRCT.

Extensive Myocardial Bridging Treated with CABG

Myocardial bridging is generally considered a benign condition, however with significant systolic compression can cause ischemia, spasm, or malignant arrhythmias. Generally, myocardial bridging occurs in the left anterior descending artery in approximately 80% of cases. First-line therapy includes beta-blockers and calcium channel blockers but refractory cases usually requires surgical intervention with myotomy or coronary artery bypass grafting. The decision to undergo surgical management of myocardial bridging is difficult as many of these patients are young and otherwise healthy therefore long-term outcomes of surgical intervention should be considered carefully prior to pursuing surgical management. We present a case of refractory anginal symptoms relieved with coronary artery bypass grafting.

Myocardial bridge in a patient with castration-resistant metastatic prostate cancer treated with enzalutamide

INTRODUCTION

Myocardial bridge is a morphological anomaly of the heart characterised by the presence of a myocardial segment above a coronary artery, which results in a higher risk of cardiovascular events. In patients with prostate cancer treated with androgen receptor-targeted agents, a higher risk of cardiotoxicity was observed.

CASE REPORT

An 88 years old man with metastatic castration-resistant prostate cancer in treatment with enzalutamide, denosumab, and triptorelin presented to our attention complaining dyspnoea and angina pectoris.

MANAGEMENT AND OUTCOME

Blood examinations revealed normal Troponin I levels. Transthoracic echocardiography revealed no signs of acute myocardial ischaemia. The treadmill stress test revealed S-T tract under levelling in V4-V6 with a very slow resolution. Coronary angiography identified a myocardial bridge in the medium tract of the interventricular anterior artery. Due to these findings, ranolazine and simvastatin were started and, after multidisciplinary assessment, we decided to continue the treatment with enzalutamide. At the first follow-up visit echocardiography found out the cardiological reports stability and no therapy changes were performed. During follow-up visit cardiological revaluation showed reports stability and no therapy changes were performed.

DISCUSSION

Due to the high prevalence of prostate cancer in elderly patients at high cardiovascular risk and the increasing use of androgen receptor-targeted agent, a multidisciplinary approach is highly recommended to weigh survival benefits on toxicities. This case report may support the use of androgen receptor-targeted agent in elderly patients with controlled cardiovascular diseases, a population that is often excluded from randomised trials.