Myocardial bridge: evaluation on MDCT

Intramyocardial and intra-atrial courses in the right coronary artery: prevalence and characteristics

PURPOSE

We aimed to determine the prevalence and radiological characteristics of myocardial bridging (MB) and intra-atrial course anomaly (IARCA), which are rare course variations of the right coronary artery (RCA), in the adult patient population.

METHODS

Radiological images of cases over the age of 18 who underwent coronary CT angiography (CTA) examination in our clinic were scanned from the archives retrospectively, and cases with MB of the RCA and IARCA detection were included in the study. The number, age and gender distribution of the cases, whether there were any other accompanying vascular anomalies, whether there was atherosclerosis in the coronary arteries (calculation of Agatston total calcium score, calculation of atherosclerotic stenosis as a percentage, if any) were evaluated.

RESULTS

The prevalence of MB in the RCA was 2.06%, and the prevalence of IARCA was 0.44%. In one case, both anomalies were detected together. The average MB segment length in RCA was 21.9 mm, and the average IARCA segment length was 37.9 mm. There was no atherosclerotic disease in the RCA segment where anomaly was detected.

CONCLUSION

Recognition of rare course anomalies of RCA before treatment procedures such as ablation and surgery is important to prevent complications that may have potentially fatal consequences.

High Prevalence of Myocardial Bridging Detected in an Indonesian Population Using Multi-Detector Computed Tomography

Background and Objectives: Myocardial bridging (MB) is still not yet considered a significant finding in Indonesia both radiographically and clinically. Hence, this article aims to assess the prevalence of MB using multi-detector computed tomography (MDCT) and look at factors contributing to stenosis amongst patients with MB. Materials and Methods: This study is cross-sectional in a single centre, with consecutive sampling, looking at all patients who underwent a multi-detector computed tomography (MDCT) scan from February 2021 until February 2023. GraphPad Prism version 9.0.0 for Windows (GraphPad Software, Boston, MA, USA) was used to analyse the results. Results: There are 1029 patients with an MB, yielding a prevalence of 44.3% (95%CI 42.3-46.4). The left anterior descending vessel is the most commonly implicated, with 99.6%. Among those with stenosis, the middle portion of the bridging vessel is the most common site of stenosis (n = 269), followed by the proximal portion (n = 237). The severity of stenosis is more often moderate, with 30-50% (n = 238). Females (odds ratio [OR] of 1.8, 95%CI 1.4-2.3; p-value < 0.0001), older age (t-value 5.6, p-value < 0.0001), symptomatic patients (OR 1.4, 95% CI 1.1-1.9; p-value = 0.013), and higher mean coronary artery calcium score (t-value 11.3, p-value < 0.0001) are more likely to have stenosis. The degree of stenosis is significantly higher in the proximal stenosis group than in the middle stenosis group (t-value 27, p-value < 0.0001). Conclusions: Our research demonstrates that MB may prevent atheromatosis of the coronary segment distal to the MB and predispose the development of atherosclerosis in the section proximal to the bridge.

Morphological analysis of myocardial bridges and coronary arterial dominance in northeast Brazil

BACKGROUND

Coronary arterial dominance and myocardial bridges have clinical implications, since a left dominant pattern associated to the presence of myocardial bridges is often associated to a higher incidence of arteriosclerosis and higher mortality by myocardial infarction.

OBJECTIVE

To determine the presence and position of myocardial bridges and their relation with coronary arterial dominance.

METHODS

Fifty-seven human cadaveric hearts were analyzed into three groups, as follows: right dominance; left dominance; codominance. Each group was then divided into two subgroups: with or without myocardial bridges. Finally, each subgroup with myocardial bridges was classified according to the position of the myocardial bridge according to the main axis of the heart (proximal, middle and distal third).

RESULTS

The right dominance occurred in most hearts (30 hearts-52,6%). Twenty-three myocardial bridges (40,3%) were identified and mostly occurred on left dominant hearts (22,8%). The pattern of coronary dominance presented a statistically significant correlation with the presence of myocardial bridges (P=0.048). The middle third of the heart axis showed the highest occurrence of myocardial bridges.

CONCLUSION

These findings suggest there is a clear relationship between the presence of myocardial bridges and left dominant pattern. Middle third of the heart axis present the higher occurrence of myocardial bridges. Knowledge of the myocardial bridges morphology is of great clinical significance, improving patient care.

Challenges in Evaluation and Management of Children with Myocardial Bridging

Myocardial bridging (MB) is a congenital anomaly where a coronary artery branch or group of branches extends inside a tunnel consisting of myocardium. Although it is mostly considered "benign," it is reported that MB may lead to significant cardiac problems and sudden cardiac deaths. While it is a congenital anomaly, its symptoms usually arise at further ages rather than childhood. The literature on MB in children is in the form of case reports or small case series. This is why pediatric cases are assessed in the light of information obtained from adults. This review compiled the literature on MB in adults and children and compared it, as well as discussing questions arising regarding the clinic, diagnosis, and treatment of MB.

Myocardial bridges: A meta-analysis

Myocardial bridges are anatomical entities characterized by myocardium covering segments of coronary arteries. In some patients, the presence of a myocardial bridge is benign and is only incidentally found on autopsy. In other patients, however, myocardial bridges can lead to compression of the coronary artery during systolic contraction and delayed diastolic relaxation, resulting in myocardial ischemia. This ischemia in turn can lead to myocardial infarction, ventricular arrhythmias and sudden cardiac death. Myocardial bridges have also been linked to an increased incidence of atherosclerosis, which has been attributed to increased shear stress and the presence of vasoactive factors. Other studies however, demonstrated the protective roles of myocardial bridges. In this study, using systematic review and a meta-analytical approach we investigate the prevalence and morphology of myocardial bridges in both clinical imaging and cadaveric dissections. We also discuss the pathophysiology, clinical significance, and management of these anatomical entities.

Coronary Anomalies in 11,267 Southwest Chinese Patients Determined by Angiography

Background

The prevalence of coronary artery anomalies (CAAs) is rare and varies among different countries or areas. More importantly, the symptoms exhibited by some CAAs make the diagnosis of coronary artery disease (CAD) difficult and hamper the physician from making the right intervention for CAD patients.

Objective

To investigate the prevalence of CAAs in 11,267 patients from three hospitals in Southwest China.

Methods

11,267 patients who have undergone coronary angiography from three Southwest China hospitals were investigated retrospectively. Dominance patterns, prevalence, and the location of each CAA were recorded and analyzed.

Results

The presence of a dominant right coronary artery (RCA) was found in 60.58% of patients. CAAs were found in 11.12% (1258) patients, and 87.66% anomalies were located in the left anterior descending (LAD) artery and its branches. Most of CAAs were found to be myocardial bridges (MBs, 1060 cases, 9.41%). Other CAAs included anomalous coronary origin (43 cases, 0.38%), coronary artery fistulas (CAFs, 36 cases, 0.32%), and coronary artery aneurysm or ectasia (119 cases, 1.06%). It also noted that most anomalies were found with RCA originating from the left coronary sinus (79.07%), most CAFs were located in the LAD and its branches (58.33%), and most coronary artery ectasias were located in the RCA (43.25%).

Conclusions

CAAs in patients from Southwest China were unique compared to other studies. Recognition of these CAAs is important for accurate diagnosis and treatment choice of patients with chest pain.

Computed Tomography Angiographic Features of Anomalous Origination of the Coronary Arteries in Adult Patients: A Literature Review and Coronary Computed Tomography Angiographic Illustrations

Computed tomography angiography not only detects atherosclerotic coronary artery disease but also helps delineate the anomalous coronary arterial anatomy that may be more than just an incidental finding and could contribute to patients' symptomatology. Additionally, identification of coronary artery anomalies is clinically significant for preoperative planning and optimizing the approach for coronary catheterizations or surgical treatments. In this work, we review rare origination anomalies of coronary arteries and illustrate their characteristics through computed tomography images.

Coronary plaque burden of the left anterior descending artery in patients with or without myocardial bridge: A case-control study based on coronary CT-angiography

BACKGROUND

The clinical significance of myocardial bridging (MB) on the left anterior descending artery (LAD) is debated. We aimed to assess the association between MB and LAD plaque volumes/compositions in a case-control set up.

METHODS

In our retrospective analysis we investigated 50 cases with incidentally recognized LAD MB and 50 matched controls without LAD MB on coronary computed tomography angiography. We quantified plaque volumes proximal to the MB and beneath it in patients with MB and in the corresponding coronary segments in patients without MB.

RESULTS

In total, we have included 100 patients (mean age 60.6 ± 10.8 years, males: 80%). Plaque volume was similar in the LAD segments proximal to the MB in cases vs. controls (150.0 mm³ [IQR: 90.7-194.5 mm³] vs. 132.8 mm³ [IQR: 94.2-184.3 mm³], respectively; p = 0.95) while the plaque volume was smaller beneath LAD MB vs. control segment (16.2 mm³ [IQR: 12.6-25.8 mm³] vs. 21.1 mm³ [IQR: 14.0-42.4 mm³], respectively; p = 0.002). No significant differences were found regarding different plaque components in segments proximal to the MB while fatty plaque and necrotic core volumes were smaller or negligible in coronary segment beneath MB than in controls (0.07 mm³ [IQR: 0.005-0.27 mm³] vs. 12.7 mm³ [IQR: 7.4-24.4 mm³] and 0.00 mm³ [IQR: 0.00-0.04 mm³] vs. 0.06 mm³ [IQR: 0.03-2.8 mm³], respectively (p < 0.001).

CONCLUSION

Comparing patients with MB vs. matched controls without it, MB was not associated with increased plaque volumes in LAD segment proximal to MB and plaque quantity was smaller in the MB segment. Our data are supportive of benign nature of incidentally recognized LAD MB.

Clinical characteristics and factors associated with coronary stenosis proximal to a myocardial bridge: a retrospective study

BACKGROUND

The association of myocardial bridge (MB) with cardiovascular risk and the possible cardiovascular risk factors remain unclear. This study aimed to explore the clinical characteristics and related factors of coronary stenosis proximal to an MB.

METHODS

This was a retrospective study of patients with symptoms of coronary atherosclerotic heart disease admitted between 10/2011 and 12/2014 to the Emergency and Cardiology Department of Bayannur Hospital, who underwent selective coronary angiography (SCAG). The patients were assigned to the non-stenosis and stenosis groups according to whether coronary stenosis was proximal to the MB.

RESULTS

Among 244 patients with MB and cardiovascular symptoms, 91 (37.3%) had stenosis proximal to the MB. Compared with the non-stenosis group, there were more males (80.2% vs. 55.6%, P < 0.001) and smokers (including those who had quit smoking) (P < 0.001) in the stenosis group. There were no significant differences in blood lipid-related indexes (TG, TC, HDL-C, LDL-C, and VLDL-C) between the two groups. Multivariable analysis suggested that MB location in the middle distal or distal segment of the left anterior descending artery (LAD) increased the odds of coronary stenosis proximal to the MB (OR = 0.439, 95% CI: 1.57-7.532, P = 0.002), which was then considered an independent factor associated with coronary stenosis proximal to the MB.

CONCLUSIONS

In patients diagnosed with an MB by SCAG, only MB located in the middle distal or distal segment of the LAD is independently associated with coronary stenosis proximal to the MB.

Difference in epicardial adipose tissue distribution between paroxysmal atrial fibrillation and coronary artery disease

BACKGROUND

An increase in epicardial adipose tissue (EAT) volume is associated with the development of atrial fibrillation (AF) and coronary artery disease (CAD), but little is known about differences in its distribution.

METHODS AND RESULTS

We included 50 patients with paroxysmal AF (PAF), 50 patients with CAD, and 50 control patients. Using multidetector computed tomography, EAT volumes surrounding the whole heart (total EAT), the atrium (atrial-EAT), and the ventricle (ventricular-EAT) were measured. EAT atrial/ventricular (A/V) ratio was calculated by dividing atrial- by ventricular-EAT volume. The total EAT volume indexes in the PAF and CAD groups were significantly larger than those in the control group. The atrial-EAT volume index in the PAF group was significantly larger than that in the CAD and control groups, whereas the ventricular-EAT volume index in the CAD group was significantly larger than that in the PAF and control groups. Thus, EAT A/V ratio was smaller in the CAD and control group than that in the PAF group (0.28 ± 0.12 vs. 0.38 ± 0.13 vs. 0.54 ± 0.33, P < .001). Univariate and multivariate linear regression analysis showed EAT A/V ratio to be independently associated with cardiovascular disease type (PAF vs. CAD; P < .001, β = .463).

CONCLUSIONS

Atrial- and ventricular-dominant distribution of EAT was observed in the PAF and CAD groups, respectively. Uneven distribution of EAT may imply the direct contribution of EAT-related inflammation to the pathogenesis of AF or CAD.

Combined Myocardial Bridge and Coronary Vessel Disease Requiring Coronary Artery Bypass Grafting and Myotomy of the Myocardial Bridge

Myocardial bridging (MB) describes a band of myocardium that covers the epicardial surface of the coronary artery. This band can vary both in thickness and distance to which it covers the artery. It is broadly classified as superficial or deep, depending on the thickness of the covering muscle layer. It can be asymptomatic, or it could present with different complications. Reported complications have included ischemia and acute coronary syndromes, coronary spasm, ventricular septal rupture, and arrhythmias. MB is most commonly found in the middle segment of the left anterior descending (LAD) coronary artery. There is controversy with regard to therapy for symptomatic patients who are refractory to medical management. Percutaneous coronary intervention and surgical myotomy (unroofing) have been proposed; yet, each one has its pros and cons. MB can be associated with the development of atherosclerosis proximal to the MB segment in the involved coronary artery, and patients can present having both pathologies. We present a case series of six patients with atherosclerotic coronary lesions requiring coronary artery bypass grafting (CABG) with an accidental perioperative finding of MB, which required myotomy.

Comparison of detection percentage and morphology of myocardial bridge between conventional coronary angiography and coronary CT angiography

Introduction: Myocardial bridge (MB) is a congenital anomaly in which a segment of a coronary artery is surrounded by myocardium. In our study, we want to use conventional coronary angiography (CCA) to describe morphologic characteristics of MB (unidentified or identified) in the patients with documented evidence of MB in coronary computed tomography angiography (CCTA). Methods: The present study was designed as cross-sectional and was conducted on 47 patients with documented evidence of MB in CCTA, who were referred to Nemazee and Faghihi hospitals for performing coronary angiography during a one year period. We compared the morphologic characteristics of tunneled segments, which were missed at CCA (unidentified), and the tunneled segments which were identified with CCA. Results: In sum, MB was found in 16 (34%) patients at CCA (identified), and it was not found in 31 (66%) patients (unidentified) based on compression sign. No significant correlation was found between the percentage of systolic compression and the length and depth of the tunneled segment in identified group (r=0.73, P = 0.18; r=1.09, P = 0.15; respectively). Degree of atherosclerotic plaque formation (diameter stenosis, percentage) (mean, 0.25 (25%) ±0.29; range, 0-0.98) of the tunneled segments in unidentified group was significantly more than the same degree (mean, 0.07 (7%) ±0.13; range, 0-0.41) of the identified group (P = 0.03). The measurement of the trapezoid area under the tunneled segment with this formula [(MB length+ intramyocardial segment) ×depth/2] had significant relation with systolic compression (r=0.304, P = 0.03) and defined the cut-off value of 250 mm² as the value of significant difference in detecting myocardial bridging with CCA. Conclusion: Our results showed that in most of identified MBs in CCA the tunneled segment area was equal and more than 250 mm². In addition, the degree of atherosclerotic plaque of the tunneled segments at CCA was significantly more in unidentified group.

Haemodynamic impacts of myocardial bridge length: A congenital heart disease

OBJECTIVES

There is an association between long and thick myocardial bridging (MB), haemodynamic perturbations and increased risk of myocardial infarction. This study aims to investigate the alteration in coronary haemodynamics with increasing the length of MB.

METHODS

Angiography and intravascular ultrasound were performed in 10 patients with varying length of MB in the left anterior descending (LAD) artery. In silico models of MB were developed based on the reconstructed three-dimensional model of the LAD. The entire LAD was divided into 3 segments, proximal (pre-bridge), bridge and distal (post-bridge). Transient computational fluid dynamics simulations were performed to derive distribution of blood residence time and wall shear stress (WSS) over entire vessel including proximal, bridge and distal segments.

RESULTS

With increasing the length of MB, a decreasing trend was observed in the WSS over proximal segment whereas an increasing trend was found in the WSS over bridge segment. When patients were divided into 2 groups based on the average length of MB in the whole cohort (L_ave = 23.92 mm), patients with bridges longer than L_ave had smaller WSS and higher residence time in the proximal segment compared to those with bridges shorter than L_ave (0.59 ± 0.31 vs 0.21 ± 0.14 Pa and 0.0021 ± 0.0015 vs 0.0045 ± 0.0021 s). In contrast, patients with bridges longer than L_ave had greater WSS in the bridge segment compared to those with bridges shorter than L_ave (1.37 ± 1.66 vs 2.53 ± 3.14 Pa). No significant difference was found in the distal WSS of patients with short and long bridges.

CONCLUSION

Our findings revealed a direct relationship between the length of MB and haemodynamic perturbations in the proximal segment such that the increased length of MB is associated with decreased WSS and increased residence time.

Morphological Features on Myocardial Bridges at the Anterior Interventricular Artery

Are described morphological features of myocardial bridges at the anterior interventricular artery obtained from the analysis of 274 cases with 312 myocardial bridges detected by angioCT performed over a period of 3.5 years on a total of 2857 subjects. CT examinations were performed on 1496 females, aged 56-79 years, and 1361 male subjects aged 34-74 years. At the level of the anterior interventricular artery we encountered 231 cases with myocardial bridges (84.31% of the total number of cases), being 267 myocardial bridges (85.58% of the total bridges analyzed). In the case of single myocardial bridges of the anterior interventricular artery, in 65 cases (33.33% of the 195 cases) they were located in the upper third of the artery, 32 cases were female (31.68% of female myocardial bridges) and 33 in male sex (35.11% of male myocardial bridges). In 129 cases (66.67%) were located in the middle third of the artery, 69 cases were female (63.30% female myocardial bridges) and 60 cases in male (64.89% of male myocardial bridges). In one case with three myocardial bridges, the inferior myocardial bridge was located in the lower third of the anterior interventricular artery. The length of the myocardial bridge was between 11.9 and 73.1 mm, for the female gender being 11.9-28.7 mm, and male 9.4-73.1 mm. The thickness of the myocardial bridge was found between 0.9-5.7 mm, for the female gender being 0.9-5.2 mm, and for the male the thickness was 1.7-5.7 mm. The caliber of the tunneling artery was found between 1.2-2.5 mm in female gender, for the male gender 1.3-4 mm.

Myocardial Bridging: A Meta-Analysis of Prevalence

The main objective of this article was to analyze prevalence data about myocardial bridging (MB) in published studies. To this purpose, we performed a meta-analysis of studies published in English literature that contained data about the prevalence of MB and its anatomical characteristics. The overall prevalence was 19% (CI: 17-21%); autopsy studies revealed an overall prevalence of 42% (CI: 30-55%), CT studies 22% (CI: 18-25%), and coronary angiography 6% (CI: 5-8%). Most bridges were located on the left anterior descending artery (82% overall, 63% on autopsy studies), had a mean thickness of 2.47 mm and a mean length of 19.3 mm. In conclusion, autopsy studies should be the gold standard in evaluating the actual prevalence of myocardial bridges, while in vivo high-resolution CT scanning should be preferred to coronary angiography studies.

Long-Term Prognosis of Patients With Intramural Course of Coronary Arteries Assessed With CT Angiography

OBJECTIVES

The aim of the present study was to evaluate, in low-to-intermediate pre-test probability patients who were referred for coronary computed tomography angiography (CTA) and did not show obstructive coronary artery disease (CAD), whether an intramural course of a coronary artery is associated with worse outcome compared with patients without an intramural course of the coronary arteries.

BACKGROUND

The prognostic value of an intramural course of the coronary arteries on coronary CTA in patients without obstructive CAD is not well-known.

METHODS

The study population consisted of 947 patients with a low-to-intermediate pre-test probability who were referred for coronary CTA and who did not have obstructive CAD. During follow-up, the occurrence of unstable angina pectoris that required hospitalization, nonfatal myocardial infarction, and all-cause mortality was evaluated.

RESULTS

On coronary CTA, 210 patients (22%) had an intramural course of a coronary artery. The median depth of the intramural course was 1.9 mm (interquartile range: 1.4 to 2.6 mm). In 84 patients (40%), the depth of the intramural course was considered deep (>2 mm surrounded by myocardium). During a median follow-up of 4.9 years (interquartile range: 3.2 to 6.9 years), a total of 43 events occurred: hospitalization due to unstable angina pectoris in 13 patients (1.4%); 7 patients (0.7%) had a nonfatal myocardial infarction; and 23 patients died (2.4%). The 6-year cumulative event rate of unstable angina pectoris requiring hospitalization (0.0% vs. 1.1%), nonfatal myocardial infarction (0.5% vs. 0.4%), all-cause mortality (1.9% vs. 2.2%) as well as the combined endpoint of all 3 events (2.4% vs. 3.7%) was similar in patients with and without an intramural course of a coronary artery.

CONCLUSIONS

In patients without obstructive CAD on coronary CTA, the presence of an intramural course of a coronary artery was not associated with worse outcome.

Prevalence of dual left anterior descending artery variations in CT angiography

PURPOSE

We aimed to evaluate the frequency and features of dual left anterior descending artery (LAD) variants using computed tomography (CT) angiography.

METHODS

A total of 1337 consecutive coronary CT angiography examinations performed between April 2010 and December 2013 were retrospectively evaluated for the presence of dual LAD. CT examinations were performed with either 64- or 320-row multidetector CT scanners. All CT angiography images were evaluated for the presence and morphologic features of dual LAD subtypes.

RESULTS

Fifty-six dual LAD variations (4%) were identified in this study population. Type 1 was the most common type of dual LAD (n=48), while Type 3 (n=3) and Type 4 (n=2) were infrequent and Type 2 was not detected. Additionally, we detected previously unclassified dual LAD variations in three cases.

CONCLUSION

Dual LAD may be a relatively more common variant than described in the medical literature, which is mostly based on catheter angiography studies. Coronary CT angiography seems markedly efficacious for detecting and documenting the anatomical details of dual LAD subtypes, as well as showing other associated cardiocoronary anomalies.

Non-invasive imaging of myocardial bridge by coronary computed tomography angiography: the value of transluminal attenuation gradient to predict significant dynamic compression

OBJECTIVES

To study the diagnostic value of transluminal attenuation gradient (TAG) measured by coronary computed tomography angiography (CCTA) for identifying relevant dynamic compression of myocardial bridge (MB).

METHODS

Patients with confirmed MB who underwent both CCTA and ICA within one month were retrospectively included. TAG was defined as the linear regression coefficient between luminal attenuation and distance. The TAG of MB vessel, length and depth of MB were measured and correlated with the presence and degree of dynamic compression observed at ICA. Systolic compression ≧50 % was considered significant.

RESULTS

302 patients with confirmed MB lesions were included. TAG was lowest (-17.4 ± 6.7 HU/10 mm) in patients with significant dynamic compression and highest in patients without MB compression (-9.5 ± 4.3 HU/10 mm, p < 0.001). Linear correlation revealed relation between the percentage of systolic compression and TAG (Pearson correlation, r = -0.52, p < 0.001) and no significant relation between the percentage of systolic compression and MB depth or length. ROC curve analysis determined the best cut-off value of TAG as -14.8HU/10 mm (area under curve = 0.813, 95 % confidence interval = 0.764-0.855, p < 0.001), which yielded high diagnostic accuracy (82.1 %, 248/302).

CONCLUSIONS

The degree of ICA-assessed systolic compression of MB significantly correlates with TAG but not MB depth or length.

KEY POINTS

• TAG is associated with the extent of dynamic compression of MB. • TAG is superior to depth and length for identifying dynamic compression. • Cut-off value of TAG as -14.8HU/10 mm yielded high predictive value.

Morphological aspects of myocardial bridges

Although some myocardial bridges can be asymptomatic, their presence often causes coronary disease either through direct compression of the "tunnel" segment or through stimulation and accelerated development of atherosclerosis in the segment proximally to the myocardial bridge. The studied material contained 30 human hearts received from the Department of Anatomy. The hearts were preserved 3 to 5 days in 10% formalin solution. Thereafter, the fatty tissue was removed and arterial blood vessels prepared by careful dissection with special reference to the presence of the myocardial bridges. Length and thickness of the bridges were measured by the precise electronic caliper. The angle between the myocardial bridge fibre axis and other axis of the crossed blood vessel was measured by a goniometer. The presence of the bridges was confirmed in 53.33% of the researched material, most frequently (43.33%) above the anterior interventricular branch. The mean length of the bridges was 14.64 ± 9.03 mm and the mean thickness was 1.23 ± 1.32 mm. Myocardial bridge fibres pass over the descending blood vessel at the angle of 10-90 degrees. The results obtained on a limited sample suggest that the muscular index of myocardial bridge is the highest for bridges located on RIA, but that the difference is not significant in relation to bridges located on other branches. The results obtained suggest that bridges located on other branches, not only those on RIA, could have a great contractive power and, consequently, a great compressive force, which would be exerted on the wall of a crossed blood vessel.

Coronary anomalies encountered in the acute setting: an imaging review

A broad spectrum of congenital coronary anomalies may be discovered on imaging and sometimes in the emergency setting on computed tomography (CT). Most coronary artery anomalies are of academic interest; however, a minority can cause morbidity and mortality and symptoms such as angina, myocardial infarction, or arrhythmias. These anomalies are usually discovered as an incidental finding on CT examinations as part of the diagnostic workup for other pathology or on dedicated coronary computed tomography angiography (CCTA) as part of the evaluation for a coronary cause of chest pain. The purpose of this pictorial review is to demonstrate the types of coronary anomalies and to enhance the clinicians' understanding of the imaging classifications and clinical implications.

Myocardial bridge as a structure of "double-edged sword" for the coronary artery

Myocardial bridge (MB) is a chance anatomical structure, comprised of the myocardial tissue, with which the coronary artery running in epicardial adipose tissue is partly covered. It is predominantly present in the left anterior descending artery (LAD) and recognizable through imaging techniques as changes in blood flow within the LAD that arises from MB contraction at cardiac systole. Such changes in blood flow influence the pathophysiology of coronary circulation and atherosclerosis development, thus generating controversy as to whether MB predisposes individual to myocardial infarction (MI). However, recent histomorphometric studies have shown that the individual anatomic properties of MB, such as location, length and thickness, consistently play a critical role in the occurrence of MI. This review article comprehensively addresses the pathophysiological mechanisms of MI occurrence together with the benign suppressive effect of coronary atherosclerosis by MB.

Relation of myocardial bridge to myocardial infarction: a meta-analysis

BACKGROUND

Small case series have suggested an association of coronary myocardial bridge (MB) with myocardial infarction (MI). However, the relationship between MB and major adverse cardiac events (MACE) remains largely unknown. The aim of this study was to assess the relationship between MB and MACE involving MI.

METHODS

We performed a systematic search of MEDLINE, PreMEDLINE, and all EMB Reviews as well as a reference list of relevant articles according to the SPICO (Study design, Patient, Intervention, Control-intervention, and Outcome) criteria using the following keywords: myocardial bridging, myocardial bridge, intramural coronary artery, mural coronary artery, tunneled coronary artery, coronary artery overbridging, etc. Bibliographies of the retrieved publications were additionally hand searched. Studies were included for the meta-analysis if they satisfied the following criteria: (1) they evaluate the association of MB with cardiovascular endpoint event; (2) they included individuals with MB and those without MB; 3) they excluded individuals with obstructive coronary artery disease (CAD). Studies were reviewed by a predetermined protocol including quality assessment. Dates were pooled using a random effect model.

RESULTS

Seven observational studies that followed 5 486 patients eligible for the enrolled criteria were included from 7 136 initially identified articles. The prevalence of MB was 24.8% (1 363/5 486). During 0.5-7.0 years of follow-up of this cohort of population, crude outcome rates were 8.0% in the MB group and 7.7% in the non-MB group. The odds ratio of overall MACE and MI were 1.34 (95% confidence interval (CI): 0.57-3.17, P = 0.51, n = 7 studies) and 2.75 (95% CI: 1.08-7.02, P < 0.03, n = 5 studies) respectively for subjects of MB compared to non-MB.

CONCLUSION

Relationship between MB and MI appears to be a real one, although the study did not reveal a connection of MB to MACE, suggesting whether the necessity of antiplatelet therapy needs to be further studied in a larger cohort of patients with MB prospectively.

Myocardial bridging analysis by coronary computed tomographic angiography in a Saudi population

AIM: To assess the incidence, location, morphology and clinical association of myocardial bridging in a Saudi population using coronary computed tomographic angiography (CCTA).

METHODS: A total of 350 CCTA of Saudi patients were included in this study (236 men, 114 women) with a mean age of 56.3 years. All patients were examined for appropriateness criteria of CCTA indications (typical chest pain, recent onset cardiomyopathy, left bundle branch block, etc.). The scans were retrospectively reviewed for the presence of myocardial bridging and any other pathological association.

RESULTS: Myocardial bridging was found in 89 of 350 (22.5%) patients. Most of the intramuscular segments were of the superficial type and found in the mid left anterior descending (LAD) (24.6%), followed by distal LAD (3.7%), diagonal branches (2%), ramus intermedius artery (1.4%) and obtuse marginal artery (0.8%). No myocardial bridging was detected in the right coronary or circumflex arteries. No significant differences were found between males and females (P = 0.14). Coronary artery atherosclerosis was found in 51 of 89 (57.3%) patients with MB. Atherosclerotic plaques were not detected in the intramuscular or distal segment of bridging arteries. Dynamic compression was observed in 35 (94.5%) patients with full encasement. No evidence of myocardial hypoperfusion was found in the territories supplied by the bridging arteries.

CONCLUSION: CCTA is excellent in analyzing myocardial bridging in a Saudi population and the results are comparable to other populations. However, finding the real incidence may need a large multicenter study.

Assessment of myocardial bridge and mural coronary artery using ECG-gated 256-slice CT angiography: a retrospective study

Recent clinical reports have indicated that myocardial bridge and mural coronary artery complex (MB-MCA) might cause major adverse cardiac events. 256-slice CT angiography (256-slice CTA) is a newly developed CT system with faster scanning and lower radiation dose compared with other CT systems. The objective of this study is to evaluate the morphological features of MB-MCA and determine its changes from diastole to systole phase using 256-slice CTA. The imaging data of 2462 patients were collected retrospectively. Two independent radiologists reviewed the collected images and the diagnosis of MB-MCA was confirmed when consistency was obtained. The length, diameter, and thickness of MB-MCA in diastole and systole phases were recorded, and changes of MB-MCA were calculated. Our results showed that among the 2462 patients examined, 336 have one or multiple MB-MCA (13.6%). Out of 389 MB-MCA segments, 235 sites were located in LAD2 (60.41%). The average diameter change of MCA in LAD2 from systole phase to diastole phase was 1.1 ± 0.4 mm, and 34.9% of MCA have more than 50% diameter stenosis in systole phase. This study suggested that 256-slice CTA multiple-phase reconstruction technique is a reliable method to determine the changes of MB-MCA from diastole to systole phase.

Anomalous Coronary Arteries

Cardiovascular computed tomographic angiography (CCTA) provides an understanding of the three-dimensional (3D) coronary artery anatomy in relation to cardiovascular thoracic structures important to the surgical management of anomalous coronary arteries (ACAs). Although some ACA variants are not clinically significant, others can lead to ischemia/infarction, related acute ventricular dysfunction, ventricular arrhythmias, and sudden cardiac death. The CCTA is important to surgical decision making, as it provides noninvasive visualization of the coronary arteries with (1) assessment of origin, course, and termination of coronary artery anomalies in the context of 3D thoracic anatomy, (2) characterization of anatomy helpful for differentiation of benign versus hemodynamically significant variants, (3) identification of other cardiothoracic anomalies, and (4) detection of coronary artery disease. High-risk ACA anatomy in the appropriate clinical setting can require surgical intervention with decisions including minimally invasive versus open sternotomy approach, correction via reimplantation of a coronary artery, alteration of the ACA course without reimplantation, or bypass of an ACA. Given the rarity of ACA, there is limited data in the literature, and significant controversy related to the management issues. The management of ACA requires comprehensive clinical history, thorough assessment of cardiac function, and detailed anatomic imaging. Future studies will need to address the long-term outcome based on detailed assessment of original anatomy and surgical approach.

Clinical value of the correlations of mural coronary artery compression extent with myocardial bridge length and thickness evaluated by 128-slice CT

This study aimed to investigate the correlations between the detection rate of mural coronary artery (MCA) by 128-slice CT and the MCA compression extent in systole with myocardial bridge (MB) length and thickness. A retrospective analysis was conducted for 580 patients receiving multislicespiral CT coronary angiography (MSCTCA). In addition, the MCA incidence rate and position were detected, and the MB length and thickness in the left anterior descending branch (LAD) and MCA compression extent in systole were measured to compare the differences between MB-MCA length and thickness among the mild, moderate and severe groups. A total of 140 cases of MB-MCA (24.14%) were involved in the study. Among them, 104 cases occurred in the middle segment of the LAD (74.3%), 16 cases (11.4%) occurred in the distal segment of the LAD, 8 cases (5.7%) occurred in the left circumflex-obtuse marginal branch (LCX-OM), 7 cases (5.0%) occurred in the first diagonal branch (1st D), 3 cases (2.1%) in the intermediate branch (M) and 2 cases (1.5%) occurred in the posterior descending branch of the right coronary artery (RCA-PD). The mean length of the MB in the LAD was 21.80±5.98 mm, the mean thickness was 2.15±0.74 mm and the mean compression extent was 38.5±19.6%. Among the different groups, there were no significant difference in MB length (P>0.05) but there were significant differences in MB thickness (P<0.05). In addition, the extent of MCA compression in systole was linearly and positively correlated with MB thickness (r=0.408, P<0.05) but was not correlated with MB length (r=0.076, P>0.05). 128-slice CT coronary angiography (SCTCA) is able to accurately detect MB-MCA and evaluate the correlations of MCA compression extent in systole with MB length and thickness which provides a basis for its clinical use.

Cellular cross-talk between epicardial adipose tissue and myocardium in relation to the pathogenesis of cardiovascular disease

Epicardial and perivascular fat depot size is considered an index of cardiac and visceral obesity. The functional and anatomic proximity of epicardial adipose tissue (EAT) to myocardium has drawn increasing attention in recent years among researchers attempting to elucidate its putative role as an endocrine organ. This includes the role of EAT as a lipid storing depot and as an inflammatory tissue secreting cytokines and chemokines under pathogenic conditions such as cardiovascular diseases. In this review, we discuss the current state of knowledge regarding the potential EAT mediators of inflammation and the paracrine cross-talk between EAT and the underlying myocardium. We also highlight the most recent findings on the causes and correlates of myocardial steatosis/cardiac lipotoxicity and its association with cardiac dysfunction.

Relationship between myocardial bridges and reduced coronary atherosclerosis in patients with angina pectoris

BACKGROUND

A myocardial bridge (MB) is a band of myocardium covering a coronary artery segment, typically located in the left anterior descending coronary artery (LAD). Bridged segments of the coronary artery are isolated from the influence of perivascular adipose tissue. The aims of this study were to investigate the relationship between MBs and atherosclerosis in bridged LAD segments and to evaluate whether perivascular adipose tissue is involved in this relationship.

METHODS

MBs were identified in the coronary arteries of patients referred for diagnostic cardiac CT. The calcium score of MBs of the LAD or, in patients without LAD-MBs, of a corresponding LAD segment at the same distance from its origin and over the same length was measured.

RESULTS

Of 128 patients, 56 (44%) had in total 73 MBs. The mean MB length was 22 ± 14 mm and the median MB thickness was 0.8mm (interquartile range 0.3-2.1mm). MBs in the LAD were present in 40 patients (31%). The calcium score was 0 in 95% of the LAD segments with MBs compared with 52% of the corresponding LAD segments without MBs. The association between LAD-MBs and calcium score (OR 0.06, 95% CI 0.01-0.25) was not influenced by age and gender, but was attenuated by local perivascular adipose tissue thickness (OR 0.35, 95% CI 0.04-2.70).

CONCLUSIONS

Coronary artery segments covered with an MB have a lower calcium score than segments without an MB. The association between MBs and calcium scores was influenced by local perivascular adipose tissue thickness.

Combined anatomical and functional imaging using coronary CT angiography and myocardial perfusion SPECT in symptomatic adults with abnormal origin of a coronary artery

There has been a lack of standardized workup guidelines for patients with congenital abnormal origin of a coronary artery from the opposite sinus (ACAOS). We aimed to evaluate the use of cardiac hybrid imaging using multi-detector row CT (MDCT) for coronary CT angiography (Coronary CTA) and stress-rest myocardial perfusion SPECT (MPS) for comprehensive diagnosis of symptomatic adult patients with ACAOS. Seventeen symptomatic patients (12 men; 54 ± 13 years) presenting with ACAOS underwent coronary CTA and MPS. Imaging data were analyzed by conventional means, and with additional use of 3D image fusion to allocate stress induced perfusion defects (PD) to their supplying coronary arteries. An anomalous RCA arose from the left anterior sinus in eight patients, an abnormal origin from the right sinus was detected in nine patients (5 left coronary arteries, LCA and 4 LCx). Five of the 17 patients (29%) demonstrated a reversible PD in MPS. There was no correlation between the anatomical variants of ACAOS and the presence of myocardial ischemia. Image fusion enabled the allocation of reversible PD to the anomalous vessel in three patients (two cases in the RCA and the other in the LCA territory); PD in two patients were allocated to the territory of artery giving rise to the anomalies, rather than the anomalies themselves. In a small cohort of adult symptomatic patients with ACAOS anomaly there was no relation found between the specific anatomical variant and the appearance of stress induced myocardial ischemia using cardiac hybrid imaging.

Myocardial bridging on coronary CTA: an innocent bystander or a culprit in myocardial infarction?

Myocardial bridging describes the clinical entity whereby a segment of coronary artery is either partially or completely covered by surrounding myocardium. It represents the most frequent congenital coronary anomaly and has an estimated prevalence of ≤13% on angiographic series. With the emergence of cardiac computed tomography and its ability to simultaneously image the coronary arteries and also the myocardium, there has been an apparent increase in the detection rates of myocardial bridges (prevalence as high as 44%). It has now become important to evaluate their clinical significance. Myocardial bridging is generally considered a benign entity with survival rates of 97% at 5 years; however, there is now emerging evidence that certain myocardial bridge characteristics may be associated with cardiovascular morbidity. The length and depth of myocardial bridges have been associated with increased atherosclerosis, whereas the degree of systolic compression has been associated with ischemia on myocardial perfusion single-photon emission tomography. On the basis of current evidence, it appears that limiting further testing for ischemia to symptomatic patients with long and/or deep myocardial brides would be appropriate.

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.

Anatomical characteristics of myocardial bridge in patients with myocardial infarction by multi-detector computed tomography

BACKGROUND

Recent development of multi-detector computed tomography (MDCT) has made the detection of myocardial bridge (MB) easier on the left anterior descending coronary artery (LAD). The LAD segment proximal to the MB is well known to be susceptible to atherosclerosis. Anatomical characteristics of MB on LAD in patients with myocardial infarction (MI) were examined by MDCT.

METHODS AND RESULTS

Subjects were 43 MI patients who had MB in the LAD and comprised 2 groups: 14 with culprit lesions in the LAD proximal to MB (culprit group) and 29 without culprit lesions in the LAD (non-culprit group). MB length, MB thickness, and the distance from the orifice of left main trunk (LMT) to MB entrance were compared. Age and coronary risk factors showed no significant difference between the 2 groups. MB length (P=0.011), MB thickness (P=0.035), and index of the length multiplied by thickness of MB (P=0.031) were significantly greater in the culprit group. The distance from the orifice of the LMT to MB entrance was significantly shorter in the culprit group (P=0.006).

CONCLUSIONS

Anatomical properties of MB, such as length and thickness of MB as well as MB location, are associated with the formation of culprit lesions of LAD proximal to MB in MI.

Imaging of coronary artery anomalies

Coronary artery anomalies (CAA) are uncommon congenital variations in coronary anatomy, occurring in 0.2% to 1.2% of the general population, the majority of which are detected incidentally and have little clinical significance. A minority of CAA, primarily due to an interarterial course, is clinically significant, and may present with symptoms of myocardial ischemia, malignant ventricular arrhythmias, and even sudden cardiac death. Until recently, CAA were primarily detected at catheter coronary angiography. With recent advances in multidetector computed tomography (CT) technology and the use of electrocardiographic gating, coronary CT angiography provides an exquisite omnidimensional display of the anomalous coronary arteries and their relation to the adjacent structures noninvasively, and is the diagnostic test of choice. Understanding CAA morphology and clinical significance of CAA is important for establishing a diagnosis, and is essential for appropriate patient management and treatment planning.

Myocardial bridging of the left anterior descending coronary artery: depiction rate and morphologic features by dual-source CT coronary angiography

Objective

To evaluate the depiction rate and morphologic features of myocardial bridging (MB) of the left anterior descending coronary artery (LAD) using dual-source CT (DSCT).

Materials and Methods

CT scans from a total of 1,353 patients who underwent DSCT were reviewed retrospectively for LAD-MB. Seventy-eight patients were excluded due to poor image quality or poor enhancement of the coronary artery. The length and depth of the MB were analyzed and classified as superficial or deep with respect to the depth (≤ 1 or > 1 mm) of the LAD tunneled segment. Superficial MB was subdivided into complete or incomplete types according to full or partial encasement of the myocardium.

Results

Of the 1,275 patients included in this study, 557 cases of MB were found from 536 patients (42%). Superficial MB was observed in 368 of 557 (66%) cases, and deep MB was seen in 189 of 557 (34%) cases. Superficial MB showed 2 types: complete (128 of 368, 35%) and incomplete (240 of 368, 65%). The mean length of a tunneled segment for superficial MB was 16.4 ± 8.6 mm. The mean length and depth of a tunneled segment for deep MB were 27.6 ± 12.8 mm and 3.0 ± 1.4 mm, respectively. The incidence of atherosclerotic plaques in a 2-cm-long segment proximal to MB was 16%.

Conclusion

The depiction rate of LAD-MB using DSCT in a large series of patients was 42%, with two-thirds of MB segments being the superficial type.

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.

Perivascular adipose tissue as a cause of atherosclerosis

Perivascular adipose tissue surrounds (coronary) arteries and may be involved in local stimulation of atherosclerotic plaque formation. Epicardial adipose tissue, the adipose tissue within the pericardium, is a frequently used measure of coronary perivascular adipose tissue and can be quantified with echocardiography, computed tomography (CT) and magnetic resonance imaging (MRI). The quantity of (coronary) perivascular adipose tissue is correlated with parameters of the metabolic syndrome, such as increased waist circumference, hypertriglyceridemia and hyperglycemia, and with coronary atherosclerosis. Coronary artery segments covered by myocardium are not exposed to coronary perivascular adipose tissue and interestingly, atherosclerosis is absent in these intra-myocardial segments. Pro-inflammatory cytokines and adipokines are expressed and secreted at a higher level in epicardial adipose tissue of patients with coronary artery disease compared to patients without coronary artery disease. Furthermore, in vitro and ex vivo perivascular adipose tissue induces inflammation of the artery wall by secretion of pro-inflammatory proteins. Atherogenesis in the vascular wall is thus stimulated from 'outside to inside'. Based on the results of clinical, ex vivo and in vitro studies, it can be argued that perivascular adipose tissue may be involved in the process of atherosclerosis.