Acute myocardial infarction or Takotsubo syndrome in a patient with stunned myocardium due to myocardial bridging? A case report of diagnostic dilemma clarified after serial workup.

BACKGROUND: Myocardial bridging is a cardiac anomaly where a segment of epicardial coronary arteries runs through the myocardium and can rarely cause MI. Takotsubo syndrome is a stress-induced cardiomyopathy that can mimic MI. Catecholamine surge during stress can contribute to Takotsubo syndrome, but whether this surge can trigger an inconspicuous myocardial bridging to manifest symptomatically remains unclear, and alternately, whether a myocardial bridge might cause worsening of Takotsubo syndrome is also a matter that needs further research. CASE PRESENTATION: We report the case of a patient who initially presented with features of acute exacerbation of bronchiectasis and subsequently developed symptoms and ECG features suggestive of acute myocardial infarction. Echocardiography revealed features of takotsubo syndrome, and complete myocardial bridging was revealed via coronary angiography. The patient was managed conservatively with pharmacological treatment, and after a few days, echocardiographic features were reversed. As such, the diagnosis shifted toward Takotsubo syndrome with myocardial stunning due to co-existent myocardial bridging. CONCLUSION: We report a rare case of a patient with acute bronchiectasis exacerbation with features suggestive of acute myocardial infarction who had findings of Takotsubo syndrome and complete myocardial bridging. In the beginning, it was difficult to determine whether the symptoms arose due to acute MI resulting from myocardial bridging or were solely due to takotsubo syndrome because of stress from bronchiectasis. Although myocardial bridging is often overlooked as an etiology for acute MI, this case highlights the importance of expanding the differential diagnosis to myocardial bridging in the work-up for the cause of acute MI and how Takotsubo syndrome can mimic acute MI and pose a diagnostic challenge.

Predictors of discordance between CT-derived fractional flow reserve (CT-FFR) and △CT-FFR in deep coronary myocardial bridging.

OBJECTIVE: To compare the performance between CT-derived fractional flow reserve (CT-FFR) and ΔCT-FFR measurements in patients with deep myocardial bridging (MB) along the left anterior descending artery, and explore the potential predictors of discordance. METHODS: 175 patients with deep MB who underwent coronary computed tomography angiography (CCTA) and CT-FFR assessment were included. Clinical, anatomical and atherosclerotic variables were compared between patients with concordant and discordant CT-FFR and ΔCT-FFR. RESULTS: 30.9 % patients were discordantly classified, in which 94.4 % patients were classified as CT-FFR+/△CT-FFR-. The discordant group showed significantly higher upstream stenosis degree, distance from MB to the aorta, △CT-FFR (P 0.007, 0.009 and 0.002, respectively), and lower CT-FFR (P < 0.001). In multivariate analysis, upstream stenosis degree (P 0.023, OR 1.628, 95 % CI: 1.068-2.481) and distance from MB to the aorta (P 0.001, OR 1.04, 95 % CI: 1.016-1.064) were independent predictors for discordance between CT-FFR and ΔCT-FFR. CONCLUSION: The discordance between CT-FFR and ΔCT-FFR measurements underscores the challenges in clinical decision-making, necessitating tailored approaches for MB evaluation.

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.

Prognostic Implications of Resistive Reserve Ratio in Patients With Nonobstructive Coronary Artery Disease With Myocardial Bridging.

BACKGROUND: Myocardial bridging (MB) is accompanied by the dynamic extravascular compression of epicardial coronary arteries, leading to intracoronary hemodynamic disturbance with abnormal coronary flow profiles. We aimed to evaluate the prognostic implications of resistive reserve ratio (RRR), a composite measure of flow and pressure parameters that represents the vasodilatory capacity of the coronary arteries, in patients with angina with nonobstructive coronary artery disease (ANOCA) and MB, in comparison with coronary flow reserve (CFR). METHODS AND RESULTS: In this retrospective cohort study, we included patients with ANOCA who underwent coronary reactivity testing, where MB was identified by transient constriction in coronary artery segments between systole and diastole. Abnormal CFR and RRR were defined as <2.5 and <2.62, respectively. Major adverse cardiac events, including cardiovascular death, stroke, myocardial infarction, heart failure, and late revascularization, served as outcomes. Among 1251 patients with ANOCA, 191 (15.3%) had MB. The prevalence of abnormal CFR or RRR was not significantly different between patients with and without MB (P=0.144 and P=0.398, respectively). Over a median follow-up time of 6.9 years, abnormal RRR predicted major adverse cardiac events in patients with MB (hazard ratio [HR], 4.38 [95% CI, 1.71-11.21]; P=0.002) and without MB (HR, 1.91 [95% CI, 1.38-2.64]; P<0.001). Abnormal CFR predicted major adverse cardiac events in patients without MB (HR, 2.15 [95% CI, 1.54-3.00]; P<0.001), whereas it was not predictive of major adverse cardiac events in patients with MB (HR, 2.29 [95% CI, 0.93-5.65]; P=0.073). CONCLUSIONS: In patients with ANOCA and MB, impaired RRR was superior to impaired CFR in distinguishing patients at a higher risk of future adverse events, suggesting that RRR may serve as a risk stratification tool in patients with MB and ANOCA.

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.

A bibliometric analysis of myocardial bridge combined with myocardial infarction.

BACKGROUND: The aim of this study is to analyze the process and frontiers of research in myocardial bridges (MB) to identify future research directions in the last 3 decades. METHODS: Relevant literature on MB combined with myocardial infarction (MI) was searched from 1991 to 2023 in the Web of Science database, and was analyzed by bibliometric analysis using VOSviewer, CiteSpace, and the R package "bibliometrix." RESULTS: A total of 1233 English articles were included in this study. The number of published articles showed an increasing trend yearly. From 2017 to 2022, the annual publication volume rose rapidly, and in 2021 the publication volume even reached 95 articles, which was the highest in all years. These publications were from 68 countries and 1854 institutions, with the leading country being the U.S. and the leading institution being Columbia University. Myoho Clinical International has a close collaborative relationship with Columbia University, while in recent years, the Harvard Medical School has explored the study of MB combined with MI. Annals of Thoracic Surgery was the journal with the highest number of publications, and Takayama Hiroo and Naka Yoshifumi were the authors with the highest number of publications. The most common keywords were MI, cardiogenic shock, and MB. CONCLUSIONS: Our findings can help researchers explore the current status of MB combined with MI research and choose new survey routes for upcoming studies. Prevalence and prognosis, mechanism of MB combined with MI and molecular mechanism may become the focus of future research. In addition, more research and cooperation are needed worldwide.

Predictors of adverse cardiac events of coronary myocardial bridging diagnosed with computed tomography angiography.

AIMS: Myocardial bridging (MB) is a frequent congenital anomaly of the epicardial coronary arteries commonly considered a benign condition. However, in some cases a complex interplay between anatomical, clinical and physiology factors may lead to adverse events, including sudden cardiac death. Coronary CT angiography (CCTA) emerged as the gold standard noninvasive imaging technique for the evaluation of MB. Aim of the study was to evaluate MB prevalence and anatomical features in a large population of patients who underwent CCTA for suspected CAD and to identify potential anatomical and clinical predictors of adverse cardiac events at long-term follow-up. METHODS AND RESULTS: Two-hundred and six patients (mean age 60.3 ± 11.8 years, 128 male) with MB diagnosed at CCTA were considered. A long MB was defined as ≥25 mm of overlying myocardium, whereas a deep MB as ≥2 mm of overlying myocardium. The study endpoint was the sum of the following adverse events: cardiac death, bridge-related acute coronary syndrome, hospitalization for angina or bridge-related ventricular arrhythmias and MB surgical treatment. Of the 206 patients enrolled in the study, 9 were lost to follow-up, whereas 197 (95.6%) had complete follow-up (mean 7.01 ± 3.0 years) and formed the analytic population. Nineteen bridge-related events occurred in 18 patients (acute coronary syndrome in 7, MB surgical treatment in 2 and hospitalization for bridge-related events in 10). Typical angina at the time of diagnosis and long MB resulted as significant independent predictors of adverse outcome. CONCLUSIONS: Typical angina and MB length ≥ 25 mm were independent predictors of cardiac events.

Myocardial bridging in obstructive hypertrophic cardiomyopathy: a risk factor for myocardial fibrosis.

BACKGROUND: Myocardial bridging (MB) is common in patients with hypertrophic cardiomyopathy (HCM). There are sparse data on the impact of MB on myocardial fibrosis in HCM. This study was designed to evaluate the relationship between MB and myocardial fibrosis in patients with obstructive HCM. METHODS: In this cohort study, retrospective data were collected from a high-volume HCM center. Patients with obstructive HCM who underwent septal myectomy and preoperative cardiac magnetic resonance (CMR) were screened from 2011 to 2018. RESULTS: Finally, 492 patients were included in this study, with an average age of 45.7 years. Of these patients, 76 patients had MB. MB occurred mostly in the left anterior descending artery (73/76). The global extent of late gadolinium enhancement (LGE) was correlated with the degree of systolic compression (r = 0.33, p = 0.003). Multivariable linear regression analysis revealed that the degree of systolic compression was an independent risk factor for LGE (ß = 0.292, p = 0.007). The LGE fraction of basal and mid anteroseptal segments in patients with severe MB (compression ratio ≥ 80%) was significantly greater than that in patients with mild to moderate MB (compression ratio < 80%). During a median follow-up of 28 (IQR: 15-52) months, 15 patients died. Kaplan-Meier analysis did not identify differences in all-cause death (log-rank p = 0.63) or cardiovascular death (log-rank p = 0.72) between patients undergoing MB-related surgery and those without MB. CONCLUSIONS: MB with severe systolic compression was significantly associated with a high extent of fibrosis in patients with obstructive HCM. Concomitant myotomy or coronary artery bypass grafting might provide excellent survival similar to that of patients without MB. Identification of patients with severe MB and providing comprehensive management might help improve the prognosis of patients with HCM.

Myocardial bridges in a pediatric population: Outcomes following a standardized approach.

OBJECTIVE: To describe clinical, functional, surgical, and outcomes data in pediatric patients with a myocardial bridge (MB) evaluated and managed following a standardized approach. METHODS: Prospective observational study included patients evaluated in the Coronary Artery Anomalies Program. Anatomy was determined by computed tomography angiography, myocardial perfusion by stress perfusion imaging, and coronary hemodynamic assessment by cardiac catheterization. RESULTS: In total, 39 of 42 patients with a complete evaluation for MB were included (December 2012 to June 2022) at a median age of 14.1 years (interquartile range, 12.2-16.4). Sudden cardiac arrest occurred in 3 of 39 (8%), exertional symptoms in 14 (36%), and no/nonspecific symptoms in 7 (18%) patients. Exercise stress test was abnormal in 3 of 34 (9%), stress perfusion imaging in 8 of 34 (24%), and resting instantaneous wave-free ratio ≤0.89 or diastolic dobutamine fractional flow reserve ≤0.80 in 11 of 21 (52%) patients. As a result, 15 of 39 (38%) patients were determined to have hemodynamically significant MB, 1 of 15 patients started beta-blocker, and 14 of 15 were referred for surgery. Myotomy (n = 11) and coronary bypass (n = 1) were performed successfully, resulting in improved symptoms and stress testing results. One patient required pericardiocentesis postoperatively, and all were discharged without other complications. At median follow-up time of 2.9 (1.8-5.8) years, all (except 2 pending surgery) were doing well without exercise restriction. CONCLUSIONS: Pediatric patients with MB can present with myocardial ischemia and sudden cardiac arrest. Provocative stress test and intracoronary hemodynamic tests helped risk-stratify symptomatic patients with MB and concern for ischemia. Surgical repair was safe and effective in mitigating exertional symptoms and stress test results, allowing patients to return to exercise without restriction.

The Association Between Myocardial Bridging and Hypertrophic Cardiomyopathy and Their Implications on Percutaneous Coronary Intervention Outcomes: A Retrospective Study.

Hypertrophic cardiomyopathy (HCM) is a complex cardiac disorder, often associated with adverse outcomes, including sudden cardiac death. Myocardial bridging (MB), where a coronary artery segment traverses intramurally within the myocardium, complicates coronary blood flow dynamics. This retrospective study investigates the relationship between MB and HCM and their impact on percutaneous coronary intervention (PCI) outcomes. Data from the 2019 National Inpatient Sample (NIS), representing 20% of U.S. hospitalizations, was utilized. Patients with both HCM and MB undergoing PCI were identified and analyzed. The study assessed inpatient outcomes, including mortality, length of stay, hospital cost, and post-PCI complications (atrial fibrillation, acute kidney injury, bleeding, coronary dissection). Patients with HCM and MB exhibited distinct demographics. The study did not find significant associations between HCM/MB and inpatient mortality, length of stay, or hospital cost. However, HCM patients had a higher incidence of atrial fibrillation and acute kidney injury post-PCI (aOR 2.33, 95% CI 1.46 to 3.71, p ≤ 0.001). MB was linked to increased occurrences of acute heart failure (aOR 0.62, 95% CI 0.42-0.92, p = 0.02) and post-PCI bleeding (aOR 4.88, 95% CI 1.17-20.2, p = 0.03). This nationwide study reveals unique demographic profiles for HCM and MB patients. Notably, HCM patients face higher risks of post-PCI complications, including atrial fibrillation and acute kidney injury. These findings provide fresh insights into the MB-HCM relationship and its implications for PCI outcomes. They emphasize the need for tailored interventions and improved patient management in cases involving both HCM and MB.

Acute Myocardial Infarction Due to Myocardial Bridge Treated With Surgery: a Case Report.

Myocardial bridging is congenital anomaly characterized by segment of epicardial coronary arteries passing through the myocardium. Various ischemic conditions are related with this pathology. We report a case of myocardial bridging that was complicated with acute anterior myocardial infarction and a review of the literature. The patient was treated successfully with coronary bypass graft surgery after unsuccessful percutaneous intervention.

A Contemporary Review of the Genomic Associations of Coronary Artery Myocardial Bridging.

BACKGROUND: Myocardial bridging (MB) is a congenital coronary artery anomaly that has limited molecular disease state characterization. Though a large portion of individuals may be asymptomatic, the myocardial ischemia caused by this anomaly can lead to angina, acute coronary syndrome, coronary artery disease, and sudden cardiac death in patients. OBJECTIVE: This study aims to summarize and consolidate the current literature regarding the genomic associations of myocardial bridge development and, in doing so, prompt further investigation into the molecular basis of myocardial bridge development. METHODS: We performed a systematic literature review of myocardial bridging using the key search terms "Myocardial Bridging" AND ("Gene" OR "Allelic Variants" OR "Genomic") in the databases of PubMed, CINAHL, EMBASE, and Cochran. We then performed a detailed review of the resulting abstracts and a full-text screening, summarizing these findings in this report. RESULTS: In total, we identified eight articles discussing the associated genomics behind MB development. Studies included review articles, case reports and genomic studies that led to the discussion of several genes: DES (E434K), FBN1 (I1175M), and COMMD10; MACROD2, SLMAP, MYH7 (A1157G), and DPP6 (A714T); MYH7 (A862V); SCN2B (E31D); and NOTCH1 (R2313Q), and to the discussion of miRNAs (miR-29b, miR-151-3p, miR-126, miR-503-3p, and miR-645). CONCLUSIONS: Our study is the first to summarize the genes and molecular regulators related to myocardial bridges as they exist in the current literature. This work concludes that definitive evidence is lacking, warranting much broader genetic and genomic studies.

Unlocking Promising Therapies: Drug-Eluting Stents in Medically Refractory Angina Patients With Myocardial Bridging.

Myocardial bridging (MB) is a congenital variation in which a coronary artery segment tunnels through the myocardium instead of following its usual epicardial route. Although MB is usually diagnosed incidentally and has a good long-term prognosis, it can lead to complications such as angina, myocardial infarction, arrhythmias, and sudden death. This study aimed to evaluate the outcomes of drug-eluting stent (DES) implantation in patients with MB and medically refractory angina. The study included 12 patients with significant MB who did not respond to maximal medical therapy and underwent DES implantation. The patients were followed up for a mean duration of 33 months. The procedural success rate was 92%, with only 1 patient experiencing acute coronary artery rupture during the procedure. During the follow-up period, none of the patients reported angina symptoms, required additional percutaneous coronary intervention, or developed stent thrombosis. One patient (8.3%) died from a non-cardiac cause. The procedure demonstrates a high procedural success rate and leads to favorable long-term outcomes, including the absence of angina symptoms and the avoidance of stent-related complications. In conclusion, this study suggests that DES implantation can serve as an effective treatment option for selected patients with medically refractory angina and significant MB.

Diagnostic Ability of Perivascular Fat Attenuation Index in Predicting Atherosclerotic Plaque Formation Proximal to Myocardial Bridging of the Left Anterior Descending Artery within 3 Years.

RATIONALE AND OBJECTIVES: This study was designed to investigate the association between the perivascular fat attenuation index (FAI) and atherosclerotic plaque formation proximal to myocardial bridging (MB) of the left anterior descending artery (LAD) within 3 years. MATERIALS AND METHODS: LAD-MB patients who underwent coronary computed tomography angiography at least twice between January 2016 and December 2022 were retrospectively included in this study. In total, 99 LAD-MB patients were included in the study. Based on the formation of atherosclerotic plaques proximal to LAD-MB during follow-up, the patients were classified into two groups: LAD-MB with plaque formation and LAD-MB without plaque formation within 3 years. The anatomical features, clinical factors, and proximal perivascular FAI of LAD-MB were measured and recorded. The association of the previously mentioned factors with the presence of atherosclerotic plaque proximal to LAD-MB was determined. RESULTS: The results showed that MB length, MB stenosis, and the perivascular FAI were significant predictors of the formation of atherosclerotic plaques proximal to LAD-MB. The area under the curve of the combined predictive model incorporating MB length, MB stenosis, and the perivascular FAI was 0.901(95% confidence interval: 0.824-0.952), with higher diagnostic performance than any other single parameter (all P < 0.05). Moreover, dynamic changes in the perivascular FAI of the vascular segments proximal to LAD-MB were higher in high-risk plaques than in non-high-risk plaques (P = 0.003). CONCLUSION: The combined use of the perivascular FAI, MB length, and MB stenosis may enable prediction of the probability of atherosclerotic plaque formation proximal to LAD-MB within 3 years. Dynamic changes in perivascular FAI were associated with the vulnerability of plaques proximal to LAD-MB.

Relationship between myocardial bridging and fatal ventricular arrhythmias in patients with hypertrophic cardiomyopathy: the HCM-MB study.

BACKGROUND: Myocardial bridging (MB) and hypertrophic cardiomyopathy (HCM) are associated with the risk of fatal ventricular arrhythmias (VAs). The goal of the study was to determine the relationship between MB and fatal VAs in HCM patients with implantable cardiac defibrillators (ICD). METHODS: A total of 108 HCM patients (mean age: 46.6 ± 13.6 years; male: 73) were enrolled in this retrospective study. All patients underwent transthoracic echocardiography and coronary computed tomography angiography. Fatal VAs including sustained ventricular tachycardia and ventricular fibrillation were documented in ICD records. RESULTS: There were documented fatal VAs in 29 (26.8%) patients during a mean follow-up time of 71.3 ± 30.9 months. Compared with the other groups, the fatal VA group had a higher incidence of the following: presence of MB (82.8 vs. 38%, p < 0.001), deep MB (62.1 vs. 6.3%, p < 0.001), very deep MB (24.1 vs. 0%, p < 0.001), long MB (65.5 vs. 11.4%, p < 0.001), presence of > 1 MB (17.2 vs. 0%, p = 0.001), and MB of the left anterior descending artery (79.3 vs. 17.7%, p < 0.001) . Sudden cardiac death (SCD) risk score (hazard ratio: 1.194; 95% CI: 1.071-1.330; p = 0.001) and presence of MB (hazard ratio: 3.815; 95% CI: 1.41-10.284; p = 0.008) were found to be independent predictors of fatal VAs in HCM patients. CONCLUSIONS: The current data suggest that the SCD risk score and presence of MB were independent risk factors for fatal VAs in patients with HCM. In addition to conventional risk factors, the coronary anatomical course can provide clinicians with valuable information when assessing the risk of fatal VAs in HCM patients.

Assessment of myocardial bridging and the pericoronary fat attenuation index on coronary computed tomography angiography: predicting coronary artery disease risk.

BACKGROUND: The fat attenuation index (FAI) is a radiological parameter that represents pericoronary adipose tissue (PCAT) inflammation, along with myocardial bridging (MB), which leads to pathological shear stress in the coronary vessels; both are associated with coronary atherosclerosis. In the present study, we assessed the predictive value of FAI values and MB parameters through coronary computed tomography angiography (CCTA) for predicting the risk of coronary atherosclerosis and vulnerable plaque in patients with MB. METHODS: We included 428 patients who underwent CCTA and were diagnosed with MB. FAI values, MB parameters, and high-risk coronary plaque (HRP) characteristics were recorded. The subjects were classified into two groups (A and B) according to the absence or presence of coronary plaque in the segment proximal to the MB. Group B was further divided into Groups B1 (HRP-positive) and B2 (HRP-negative) according to the HRP characteristic classification method. The differences among the groups were analysed. Multiple logistic regression analysis was performed to determine the independent correlation between FAI values and MB parameters and coronary atherosclerosis and vulnerable plaque risk. RESULTS: Compared to the subjects in Group A, those in Group B presented greater MB lengths, MB depths and muscle index values, more severe MB systolic stenosis and higher FAIlesion values (all P < 0.05). In multivariate logistic analysis, age (OR 1.076, P < 0.001), MB systolic stenosis (OR 1.102, P < 0.001) and FAIlesion values (OR 1.502, P < 0.001) were independent risk factors for the occurrence of coronary atherosclerosis. Compared to subjects in Group B2, those in Group B1 presented greater MB lengths and higher FAI values (both P < 0.05). However, only the FAIlesion value was an independent factor for predicting HRP (OR 1.641, P < 0.001). CONCLUSION: In patients with MB, MB systolic stenosis was associated with coronary plaque occurrence in the segment proximal to the MB. The FAI value was not only closely related to coronary atherosclerosis occurrence but also associated with plaque vulnerability. FAI values may provide more significant value in the prediction of coronary atherosclerosis than MB parameters in CCTA.

Clinical Implication and Optimal Management of Myocardial Bridging: Role of Cardiovascular Imaging.

Myocardial bridging (MB) was historically considered a benign structure as most people with MB are clinically asymptomatic. Recently, however, mounting evidence indicates that MB can cause adverse cardiac events owing to arterial systolic compression/diastolic restriction, atherosclerotic plaque progression upstream from MB, and/or vasospastic angina. In MB patients with refractory angina, the optimal treatment strategy should be determined individually based on versatile anatomic and hemodynamical assessments that often require multidisciplinary diagnostic approaches. The present review summarizes the clinical implication and management of MB, highlighting the role of imaging modalities currently available in this arena.