Assessment of the Ischaemic Effects of Myocardial Bridge by Echocardiographic Exercise Stress Test.

Background: Detection of myocardial bridge (MB) at angiography suggests it has a role in ischaemic-related symptoms in patients with angina without obstructive coronary artery disease. However, evidence that MB may cause myocardial ischaemia is limited. Methods: We studied 41 patients with MB of the left anterior descending coronary artery and otherwise normal coronary arteries. Fourteen patients with normal coronary arteries and without MB served as controls. All subjects underwent a maximal treadmill exercise stress test (EST) under ECG monitoring. Standard and speckle-tracking echocardiography were performed at baseline and immediately after peak EST. Results: EST duration and peak heart rate and systolic pressure were similar in the two groups. A positive EST (ST-segment depression .1 mm) was found in 18 patients in the MB group (43.9%) and none in the control group (p=0.001). No abnormalities in both left ventricle systolic and diastolic function were found between the two groups in the standard echocardiographic evaluation. Global and segmental (anterior, inferior) longitudinal strain (LS) did not differ at baseline between the groups. There was a small increase in global LS during EST in MB patients but not in the control group (p=0.01). Similar trends were found for regional LSs, with differences being significant for the medium (p=0.028) and apical (p=0.032) anterior segments. No differences in echocardiographic parameters and both global and segmental LSs were observed between MB patients with ischaemic ECG changes during EST versus those without. Conclusion: Our findings do not support the notion that MB results in significant degrees of myocardial ischaemia during maximal myocardial work.

Myocardial Bridge and Atherosclerosis, an Intimal Relationship.

PURPOSE OF REVIEW: This review investigates the relationship between myocardial bridges (MBs), intimal thickening in coronary arteries, and Atherosclerotic cardiovascular disease. It focuses on the role of mechanical forces, such as circumferential strain, in arterial wall remodeling and aims to clarify how MBs affect coronary artery pathology. REVIEW FINDINGS: MBs have been identified as influential in modulating coronary artery intimal thickness, demonstrating a protective effect against thickening within the MB segment and an increase in thickness proximal to the MB. This is attributed to changes in mechanical stress and hemodynamics. Research involving arterial hypertension models and vein graft disease has underscored the importance of circumferential strain in vascular remodeling and intimal hyperplasia. Understanding the complex dynamics between MBs, mechanical strain, and vascular remodeling is crucial for advancing our knowledge of coronary artery disease mechanisms. This could lead to improved management strategies for cardiovascular diseases, highlighting the need for further research into MB-related vascular changes.

Association of Coronary Computed Tomography-Defined Myocardial Bridge With Pre- and Post-Procedural Fractional Flow Reserve in Patients Undergoing Elective Percutaneous Coronary Intervention.

BACKGROUND: Myocardial bridge (MB) is a common coronary anomaly characterized by a tunneled course through the myocardium. Coronary computed tomography angiography (CCTA) can identify MB. The impact of MB detected by CCTA on coronary physiological parameters before and after percutaneous coronary intervention (PCI) is unknown.Methods and Results: We investigated 141 consecutive patients who underwent pre-PCI CCTA and fractional flow reserve (FFR)-guided elective PCI for de novo single proximal lesions in the left anterior descending artery (LAD). We compared clinical demographics and physiological parameters between patients with and without CCTA-defined MB. MB was identified in 46 (32.6%) patients using pre-PCI CCTA. The prevalence of diabetes was higher among patients with MB. Median post-PCI FFR values were significantly lower among patients with than without MB (0.82 [interquartile range 0.79-0.85] vs. 0.85 [interquartile range 0.82-0.89]; P=0.003), whereas pre-PCI FFR values were similar between the 2 groups. Multivariable linear regression analysis revealed that the presence of MB and greater left ventricular mass volume in the LAD territory were independently associated with lower post-PCI FFR values. Multivariable logistic regression analysis also revealed that the presence of MB and lower pre-PCI FFR values were independent predictors of post-PCI FFR values ≤0.80. CONCLUSIONS: CCTA-defined MB independently predicted both lower post-PCI FFR as a continuous variable and ischemic FFR as a categorical variable in patients undergoing elective PCI for LAD.

A Rare Presentation of Myocardial Bridging With Heart Failure Symptoms.

Myocardial bridging is an under-recognized cause of angina. This congenital anomaly occurs when a segment of the epicardial coronary artery has a short intra-myocardial course. A significant intra-myocardial course may lead to ischemia, causing anginal symptoms. In this case report, we discuss a rare presentation of myocardial bridging with symptoms of heart failure. The pathology led to a marked degree of ventricular dysfunction and a significant drop in cardiac output (CO), and the patient had severe exertional dyspnea and functional limitations. The ischemic workup with diagnostic imaging and angiograms failed to explain the severity of symptoms, which were only evident in hemodynamic studies and cardiopulmonary exercise testing.

Distraction-aware hierarchical learning for vascular structure segmentation in intravascular ultrasound images.

Vascular structure segmentation in intravascular ultrasound (IVUS) images plays an important role in pre-procedural evaluation of percutaneous coronary intervention (PCI). However, vascular structure segmentation in IVUS images has the challenge of structure-dependent distractions. Structure-dependent distractions are categorized into two cases, structural intrinsic distractions and inter-structural distractions. Traditional machine learning methods often rely solely on low-level features, overlooking high-level features. This way limits the generalization of these methods. The existing semantic segmentation methods integrate low-level and high-level features to enhance generalization performance. But these methods also introduce additional interference, which is harmful to solving structural intrinsic distractions. Distraction cue methods attempt to address structural intrinsic distractions by removing interference from the features through a unique decoder. However, they tend to overlook the problem of inter-structural distractions. In this paper, we propose distraction-aware hierarchical learning (DHL) for vascular structure segmentation in IVUS images. Inspired by distraction cue methods for removing interference in a decoder, the DHL is designed as a hierarchical decoder that gradually removes structure-dependent distractions. The DHL includes global perception process, distraction perception process and structural perception process. The global perception process and distraction perception process remove structural intrinsic distractions then the structural perception process removes inter-structural distractions. In the global perception process, the DHL searches for the coarse structural region of the vascular structures on the slice of IVUS sequence. In the distraction perception process, the DHL progressively refines the coarse structural region of the vascular structures to remove structural distractions. In the structural perception process, the DHL detects regions of inter-structural distractions in fused structure features then separates them. Extensive experiments on 361 subjects show that the DHL is effective (e.g., the average Dice is greater than 0.95), and superior to ten state-of-the-art IVUS vascular structure segmentation methods.

Myocardial Bridging of Mid-left Anterior Descending Artery (LAD) Presenting As Transient Left Bundle Branch Block During Nuclear Stress Test.

Transient left bundle branch block occurring during a nuclear stress test in the setting of myocardial bridging is a relatively rare finding. We report a case of a 75-year-old male who presented with typical stable angina. Serial troponins were negative, and the electrocardiogram revealed normal sinus rhythm with left ventricular hypertrophy and T-wave inversions in the lateral leads. The nuclear stress test was non-ischemic but showed a transient left bundle branch block associated with chest pain and shortness of breath that occurred right after the administration of regadenoson. Coronary angiography revealed non-obstructive coronary artery disease and a mid-LAD myocardial bridge.

Mid-ventricular Takotsubo Cardiomyopathy With Coexisting Myocardial Bridge.

Typical takotsubo cardiomyopathy (TCM) is a reversible form of myocardial injury that presents with a characteristic ballooning abnormality of the left ventricular apex. Typical TCM has been associated with myocardial bridging; however, mid-ventricular variant TCM has not. We describe a rare case of mid-ventricular variant TCM with a coexisting left anterior descending artery myocardial bridge and discuss management strategies. Furthermore, we propose potential pathophysiological mechanisms that may contribute to the symptomatic presentation of both conditions as a manifestation of common etiological factors.

Presence and Relevance of Myocardial Bridge in LAD-PCI of CTO and Non-CTO Lesions.

BACKGROUND: Intravascular ultrasound (IVUS) studies show that one-quarter of left anterior descending (LAD) arteries have a myocardial bridge. An MB may be associated with stent failure when the stent extends into the MB. OBJECTIVES: The aim of this study was to investigate: 1) the association between an MB and chronic total occlusion (CTO) in any LAD lesions; and 2) the association between an MB and subsequent clinical outcomes after percutaneous coronary intervention in LAD CTOs. METHODS: A total of 3,342 LAD lesions with IVUS-guided percutaneous coronary intervention (280 CTO and 3,062 non-CTO lesions) were included. The primary outcome was target lesion failure (cardiac death, target vessel myocardial infarction, definite stent thrombosis, and ischemic-driven target lesion revascularization). RESULTS: An MB by IVUS was significantly more prevalent in LAD CTOs than LAD non-CTOs (40.4% [113/280] vs 25.8% [789/3,062]; P < 0.0001). The discrepancy in CTO length between angiography and IVUS was greater in 113 LAD CTOs with an MB than 167 LAD CTOs without an MB (6.0 [Q1, Q3: 0.1, 12.2] mm vs 0.2 [Q1, Q3: -1.4, 8.4] mm; P < 0.0001). Overall, 48.7% (55/113) of LAD CTOs had a stent that extended into an MB after which target lesion failure was significantly higher compared to a stent that did not extend into an MB (26.3% vs 0%; P = 0.0004) or compared to an LAD CTO without an MB (26.3% vs 9.6%; P = 0.02). CONCLUSIONS: An MB was more common in LAD CTO than non-CTO LAD lesions. If present, approximately one-half of LAD CTOs had a stent extending into an MB that, in turn, was associated with worse outcomes.

Normalization of FFRCT after surgical unroofing of a myocardial bridge: a case report.

Background: Cardiac computed tomography angiography derived fractional flow reserve (FFRCT) is a diastolic measurement and has emerged as a valuable non-invasive alternative to FFR in patients with stable coronary artery disease. It has, unlike FFR during coronary angiography, not been validated for the physiological evaluation of an isolated myocardial bridge (MB) so far. Case summary: Our patient, previously known with a long myocardial bridge of the mid-segment of the left anterior descending artery, presented with a non-ST-segment elevation myocardial infarction that was treated by surgical unroofing of the MB. FFRCT after surgery confirms a major amelioration of coronary blood flow. Discussion: Myocardial bridge may rarely present as a non-ST-segment elevation myocardial infarction. FFRCT has thus far been accepted as a useful diagnostic tool in stable coronary artery disease. Our case report suggests that cardiac computed tomography angiography may be considered a useful technique for anatomical and physiological evaluation of MBs.

Combined intra-cavitary course of left anterior descending artery and myocardial bridge of right coronary artery in right ventricle hypertrophy: a case report.

Background: Intra-cavitary (IC) coronary course is a rare anatomical variant that has become more commonly reported in the last decade. While the condition is generally benign and often discovered incidentally during coronary computed tomography angiography (CCTA), these arteries are vulnerable to injury during cardiac interventions. It is unclear whether right ventricle (RV) pathology, such as dilatation or hypertrophy, plays a role in this condition. Case summary: A patient in their fifties with a medical history of rheumatic heart disease and atrial fibrillation presented with dyspnoea and orthopnea but denied any previous chest pain. Upon examination, the patient exhibited slow atrial fibrillation and generalized anasarca. Echocardiography revealed severe mitral stenosis, tricuspid regurgitation, pulmonary hypertension, and a significantly dilated and impaired RV. Before surgery, a CCTA was performed and revealed an abnormal mid-left anterior descending (LAD) course through the RV cavity with complete systolic attenuation. This finding was later confirmed through invasive angiography. Additionally, the right coronary artery (RCA) showed a mid-segment myocardial bridge (MB). The patient was scheduled for mitral and tricuspid valves' surgery with no planned intervention to the LAD or RCA. Discussion: Coronary IC course is a rare finding that poses a risk of arterial injury during invasive cardiac procedures. It is important for all cardiac interventionists to be familiar with this diagnosis and the potential hazards during cardiac interventions. Further research is needed to determine whether RV dilatation or hypertrophy can exacerbate coronary IC course or MB.

A framework of myocardial bridge detection with x-ray angiography sequence.

BACKGROUND: Myocardial bridges are congenital anatomical abnormalities in which myocardium covers a segment of coronary arteries, leading to stenocardia, myocardial ischemia, and sudden cardiac death in severe cases. However, automatic diagnosis of myocardial bridge presents significant challenges. METHOD: A novel framework of myocardial bridge detection with x-ray angiography sequence is proposed, which can realize automatic detection of vessel stenosis and myocardial bridge. Firstly, we employ a novel neural network model for coronary vessel segmentation, which consists of both CNNs and transformer structures to effectively extract both local and global information of the vessels. Secondly, we describe the vessel segment information, establish the vessel tree in the image, and fuse the vessel tree information between sequences. Finally, based on vessel stenosis detection, we realize automatic detection of the myocardial bridge by querying the blood vessels between the image sequence information. RESULTS: In experiment, we evaluate the segmentation results using two metrics, Dice and ASD, and achieve scores of 0.917 and 1.39, respectively. In the stenosis detection, we achieve an average accuracy rate of 92.7% in stenosis detection among 262 stenoses. In multi-frame image processing, vessels in different frames can be well-matched, and the accuracy of myocardial bridge detection achieves 75%. CONCLUSIONS: Our experimental results demonstrate that the algorithm can automatically detect stenosis and myocardial bridge, providing a new idea for subsequent automatic diagnosis of coronary vessels.

Myocardial bridge in a child with cardiac arrest and ventricular fibrillation: a bridge over troubled water?

Resuscitated cardiac arrest in a child triggers a comprehensive workup to identify an aetiology and direct management. The presence of a myocardial bridge does not automatically imply causation. Careful determination of the haemodynamic significance of the myocardial bridge is critical to avoid an unnecessary sternotomy and to provide appropriate treatment.

Myotomy for myocardial bridge utilizing harmonic scalpel.

INTRODUCTION: Myocardial bridge is defined as epicardial coronary arteries that course through the myocardium. While frequently asymptomatic, it can present on a spectrum from stable to life threatening angina. Medical management is often successful, but failure requires stenting or bypass, both of which are inferior to myotomy in appropriate surgical candidates, the former due to morbidity and the later theoretically due to competitive flow. PRESENTATION OF CASE: We present an otherwise healthy 50 year old gentleman with myocardial bridge refractory to medical management who was effectively managed via myotomy performed with the harmonic scalpel, enjoying complete relief of previous exertional chest pain. DISCUSSION: Historically, myotomy has been described sharply and with electrocautery. Compared to the harmonic scalpel, these techniques risk poor hemostasis and damage to the underlying left anterior descending artery, not to mention their inefficiency in terms of operative speed. CONCLUSION: In appropriately diagnosed patients, who are also suitable surgical candidates, myotomy, specifically with the harmonic scalpel, has short-term, intra-operative benefits of better hemostasis, protection of underlying left anterior descending artery and heart cavity, and improved operative efficiency. Given the lack of long-term symptomatic data on different myotomy techniques it is difficult to make comparisons of this nature.

A Comprehensive Review of Myocardial Bridging: Exploring Diagnostic and Treatment Modalities.

Myocardial bridging (MB) is a congenital coronary artery anomaly involving an overlying myocardium's partial or complete encasement of a coronary artery segment. The obstruction can lead to significant cardiac symptoms, resulting in myocardial ischemia, arrhythmia, and sudden cardiac death. Several approaches, including invasive and non-invasive methods, have been proposed to diagnose and manage MB. Invasive modalities, such as intravascular ultrasound (IVUS) and coronary angiography, offer high specificity and sensitivity. In contrast, non-invasive methods like Doppler ultrasound, multislice computed tomography (MSCT), and magnetic resonance imaging (MRI) are advantageous due to their non-invasive nature, high sensitivity and specificity, and cost-effectiveness. Treatment options for MB mainly focus on relieving symptoms and preventing adverse outcomes. The use of pharmacological agents and surgical and percutaneous interventions has been documented in numerous studies. Studies conclude that MB is a treatable cardiac anomaly, and a combined approach of diagnosis, treatment, and follow-up is necessary to reduce the morbidity and mortality associated with this condition.

Challenge in Diagnosis and Management of a Patient With Myocardial Bridge and Coronary Artery Spasm.

Positive ischemia by noninvasive imaging studies often results in nonobstructive disease in cardiac catheterization. In this case, we observed ischemia by nuclear stress test in only the anteroseptal area, and the apex is free of ischemia. Coronary angiogram findings were unremarkable, but intravascular ultrasound confirmed the long length of the myocardial bridge. Further testing with spasm provocation and microvascular testing showed diffuse epicardial spasm in this area of myocardial bridge without microvascular dysfunction. We observed the myocardial bridge but no microvascular dysfunction. This case illustrates the coexistence of spasm in the area of a myocardial bridge and the challenges in the medical management of these patients. (Level of Difficulty: Advanced.).

The relationship between CTA performances and cardiac function indicators in myocardial bridge and mural coronary artery.

OBJECTIVE: To investigate the relationship between computed tomography angiography (CTA) performances and cardiac function indicators in patients with myocardial bridge and mural coronary artery (MB-MCA). METHODS: The clinical data of 60 patients with MB-MCA receiving CTA in the First Hospital of Zhangjiakou from January 2021 to February 2022 were analyzed retrospectively. The patients were divided into different groups based on CTA performances, including the degree of stenosis of the left anterior descending (LAD) MCA, whether there was atherosclerosis in the anterior segment of MB of LAD branch, the MB thickness, and the degree of stenosis of the LAD branch. The correlation between these TCA performances and cardiac function indicators including end-systolic volume (ESV), end-diastolic volume (EDV), stroke volume (SV), cardiac output (CO), and left ventricular ejection fraction (LVEF) was analyzed. Besides, the receiver operating characteristic (ROC) curve was used to analyze the predictive performance of cardiac function indicators for the severity of MB-MCA. RESULTS: ESV, EDV, SV, CO and LVEF were statistically different between the moderate stenosis group and mild stenosis group (all P < 0.05). EDV, SV, CO, and LVEF were statistically different between the atherosclerosis group and non-atherosclerosis group (all P < 0.05). SV, CO, LVEF in the deep group were lower than that in the superficial group (all P < 0.05). EDV, CO, LVEF were different between the LAD moderate stenosis group and LAD mild stenosis group (all P < 0.05). The AUC (areas under the curve) of combined detection of ESV, EDV, SV, CO, and LVEF in predicting the severity of MB-MCA was 0.907, which was higher than the single indicator predictive effect. CONCLUSIONS: Cardiac function indicators, mainly CO and LVEF are correlated with the CTA performance of MB-MCA patients. The combination of cardiac function indicators has a good effect in predicting the severity of MB-MCA.

Worsening of Angina Following Nitroglycerin Administration: A Case Report of the Interplay With Undiagnosed Myocardial Bridge.

Myocardial bridge (MB) is a congenital abnormality where part of a coronary epicardial artery runs under the myocardium fibers and is compressed in systole; this becomes more pronounced when nitroglycerin (NTG) is administered. In this report, we describe the case of a 40-year-old African American man who presented with chest pain that did not respond to NTG or isosorbide mononitrate and was only partially relieved by narcotics. His past medical history was significant for coronary artery disease (CAD) with a stent into the left anterior descending artery (LAD) several months prior, hypertension, hyperlipidemia, paroxysmal atrial fibrillation, sick sinus syndrome, permanent pacemaker, pulmonary embolism, and cerebral vascular accident. No explanation for his angina was found either in the previous outpatient left heart catheterization (LHC) procedures demonstrating LAD stent patency or initial chest pain workup upon admission. Functional LHC procedure with adenosine infusion and acetylcholine provocation demonstrated endothelial dysfunction with notable epicardial spasm and MB of the LAD that worsened with NTG. Cardiology advised dual antiplatelet therapy and a statin as part of treatment for CAD and a calcium channel blocker with a bradycardic effect (e.g., diltiazem, verapamil) for the MB and coronary vasospasm, and avoidance of NTG and long-acting nitrates (e.g., isosorbide mononitrate), which can cause reflex tachycardia and worsen angina from MB. A selective serotonin reuptake inhibitor was added for increased cardiac nociception. The patient's pain resolved, and he was discharged. MB is an important alternate etiology to consider when chest pain does not respond to NTG administration for adjustment of treatment modalities. The initial treatment for this patient's pain with NTG likely exacerbated symptoms by reducing intrinsic coronary wall tension and subsequently increasing reflex sympathetic stimulation of contractility of the left ventricular myocardium, which can, in turn, increase anginal symptoms and ischemia.

The Role of Coronary CT Angiography in the Evaluation of Dual Left Anterior Descending Artery Prevalence and Subtypes: A Retrospective Multicenter Study.

BACKGROUND: The aim of this multicenter study was to evaluate the prevalence and features of dual left anterior descending artery (LAD) subtypes using coronary CT angiography (CCTA). METHODS: A retrospective multicenter analysis of 2083 CCTA from December 2020 to November 2022 was conducted to search for the presence and morphological features of dual LAD. The two classifications used were the updated classification of Spindola-Franco and the Jariwala classification. Statistical tests were conducted to evaluate the prevalence of dual LADs among sexes and its association with angina in patients without significant coronary stenoses and/or associated cardiac anomalies. RESULTS: Dual LAD was observed in 124 (5.96%) patients analyzed. According to the Spindola-Franco revisited classification, type I dual LAD was the most common (71/124, 57.26%). According to the Jariwala classification, all cases were group I. In the general population, there was a higher prevalence of dual LAD among females (7.3% females vs. 5.1% males; p value: 0.04). No statistically significant difference was found in the prevalence of angina in the dual LAD population compared to the no dual LAD population (2.1% vs. 1.5%; p value: 0.10). CONCLUSIONS: The acknowledgment and reporting of LAD duplication is helpful for an optimal management of coronary patients with this condition. Dual LAD was more frequent in the female population, mainly not related with angina. Myocardial bridge was more frequent in the dual LAD population than in the no dual LAD population.

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.