Long-term clinical course of patients with isolated myocardial bridge

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.

Incidence and Morphological Study of Myocardial Bridge in the State of Ceará: A Cadaveric Study

BACKGROUND

Myocardial bridges (MB) are anatomical anomalies with possible clinical repercussions; hence, their understanding deserves attention.

OBJECTIVE

To determinate the prevalence and characterize MB in human hearts from the state of Ceará. Methods: Fifty hearts of adult human cadavers from the Medicine School of Federal University of Ceará, Brazil. The hearts were dissected to identify MBs that pass over part of the coronary artery. The segment of the artery (proximal, middle, and distal) with a bridge was identified. The external diameter of the artery at the proximal and distal points of the MB was measured. The length and thickness of the MB were also measured with an electronic caliper. The muscle index (MMI) of the MB was calculated as the product of length and thickness expressed in millimeters. The significance level adopted in the statistical analysis was 5%.

RESULTS

MB was confirmed in 40% of sample. Approximately one third of the sample had only 1 MB. MB was most frequently found over the anterior interventricular branch of the left coronary artery (59.25%, p=0.02), and its prevalence in other branches was much lower (22.23%). The most affected segments of arteries were the superior (44.44%) and medium (40.74%). The mean diameter of arteries proximal to the MB was 2.38±0.97mm (range=0.78-5.15mm), and the diameter distal to the MB was 1.71±0.75mm (range=0.42-3.58mm). The length was measured as mean=8.55±5.27mm, while the mean thickness was 0.89±0.33mm.

CONCLUSION

A high prevalence of MB is more likely to affect the left coronary artery system with larger MMI than other affected branches.

Impact of Clinical and Morphological Factors on Long-Term Mortality in Patients with Myocardial Bridge

Although myocardial bridging (MB) has been intensively investigated using different methods, the effect of bridge morphology on long-term outcome is still doubtful. We aimed at describing the anatomical differences in coronary angiography between symptomatic and non-symptomatic LAD myocardial bridges and to investigate the influence of clinical and morphological factors on long-term mortality. In our retrospective, long-term, single center study we found relevant MB on the left anterior descendent (LAD) coronary artery in 146 cases during a two-year period, when 11,385 patients underwent coronary angiography due to angina pectoris. Patients were divided into two groups: those with myocardial bridge only (LAD-MBneg, n = 78) and those with associated obstructive coronary artery disease (LAD-MBpos, n = 68). Clinical factors, morphology of bridge by quantitative coronary analysis and ten-year long mortality data were collected. The LAD-MBneg group was associated with younger age and decreased incidence of diabetes mellitus, as well as with increased minimal diameter to reference diameter ratio (LAD-MBneg 54.5 (13.1)% vs. LAD-MBpos 46.5 (16.4)%, p = 0.016), while there was a tendency towards longer lesions and higher vessel diameter values compared to the LAD-MBpos group. The LAD-MBpos group was associated with increased mortality compared to the LAD-MBneg group. The analysis of our data showed that morphological parameters of LAD bridge did not influence long-term mortality, either in the overall population or in the LAD-MBneg patients. Morphological parameters of LAD bridge did not influence long-term mortality outcomes; therefore, it suggests that anatomical differences might not predict long-term outcomes and should not influence therapy.

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.

Associations of myocardial bridging with adverse cardiac events: a meta-analysis of published observational cohort studies involving 4,556 individuals

Background

Data derived from small series have demonstrated an association of myocardial bridge (MB) with adverse cardiac events, while MB has been traditionally considered as a benign condition. Hence, the precise clinical implications of MB on prognosis remains inconsistent. Our purpose is to perform a meta-analysis to assess the clinical implications of MB on prognosis.

Methods

We performed an extensive search of PubMed and reference lists of relevant articles. Studies which compared prognosis between subjects with and without MB were identified from 1960 to 31 March 2018. Studies selection was limited to human data and restricted to English language.

Results

Six eligible studies were included in current meta-analysis. Of 4,556 subjects, 1,389 (30.5%) presented MB. MB was associated with an increased risk of adverse cardiac events [odds ratio (OR), 1.71; 95% confidence interval (CI): 1.29 to 2.26; P=0.0002], non-fatal myocardial infarction (OR: 3.17; 95% CI: 1.21 to 8.31; P=0.02), and angina requiring hospitalization (OR: 2.31; 95% CI: 1.55 to 3.45; P<0.0001), respectively, compared with subjects without MB.

Conclusions

This meta-analysis of currently available observational cohort studies suggests that MB has an association with adverse cardiac events. Further prospective multicenter studies with large sample size are needed to confirm current findings. Moreover, studies refining the impact of different types of MB on cardiac events, myocardial ischemia, and symptoms requiring therapy, may provide more insights to this issue.

Ischaemic papillary muscle rupture without significant coronary artery lesion

Papillary muscle rupture is a rare but life-threatening complication of myocardial infarction (MI). Here, we describe a case of papillary muscle rupture caused by a microscopic MI. A 76-year-old woman was referred to our institution, where she developed cardiac arrest upon admission. Severe mitral regurgitation was noted without significant coronary artery lesions. Emergency surgery was performed, and posteromedial papillary muscle rupture was observed. Postoperatively, cardiac magnetic resonance imaging revealed a microscopic MI of the posteromedial papillary muscle.

What is the optimal treatment for symptomatic patients with isolated coronary myocardial bridge? A systematic review and pooled analysis

BACKGROUND

Myocardial bridging is a common coronary anomaly, with few severe adverse events but a relevant symptom burden. Myocardial bridging treatment, however, remains uncertain because of the lack of randomized trials.

MATERIAL

MEDLINE/PubMed was systematically screened for studies reporting on isolated myocardial bridging diagnosed at coronary angiography or with coronary computed tomography in patients admitted for suspected angina or with an acute coronary syndrome. Baseline, treatment and outcome data were appraised and pooled according to treatment (medical therapy, bypass surgery/myotomy or stenting).

RESULTS

A total of 899 patients in 18 studies were included with a low prevalence of traditional risk factors, especially diabetes (15.6%, interquartile range 2.5-21.5). After a median of 31.0 months (interquartile range 12.4-37.1), major cardiovascular events (composite of death, myocardial infarction or target vessel revascularization) occurred in only 3.4% of the study patients and 78.7% [70.5-86.9; 95% confidence intervals (CI)] were managed conservatively and free of symptoms. When an invasive strategy was planned, freedom from angina was higher in patients treated with surgery [84.5% (78.4-90.7; 95% CI)] than in those treated with stenting [54.7% (38.9-70.6; 95% CI)]. Patients in the stenting group experienced a high incidence of major cardiovascular events related to target vessel revascularization [40.07% (19.83-60.32; 95% CI)]. Meta-regression showed that patients treated with beta-blockers or with a history of hypertension were more likely to remain free from angina (B -0.6, P = 0.013; B -0.66, P = 0.006).

CONCLUSION

Patients with symptomatic isolated myocardial bridging generally have a good long-term prognosis. Pharmacological treatment alone, especially with beta-blockers, is able to improve angina in most cases. Surgical treatment appears to be more effective than stenting in nonresponders.

Cardiovascular consequences of myocardial bridging: A meta-analysis and meta-regression

Myocardial bridging, a congenital abnormality in which a coronary artery tunnels through the myocardial fibres was usually considered a benign condition. Many studies suggested a potential hemodynamic significance of myocardial bridging and some, usually case reports, implied a possible correlation between it and various cardiovascular pathologies like acute myocardial infarction, ventricular rupture, life-threatening arrhythmias, hypertrophic cardiomyopathy, apical ballooning syndrome or sudden death. The main objective of this article is to evaluate whether myocardial bridging may be associated with significant cardiac effects or if it is strictly a benign anatomical variation. To this purpose, we performed a meta-analysis (performed using the inverse variance heterogeneity model) and meta-regression, on scientific articles selected from three main databases (Scopus, Web of Science, Pubmed). The study included 21 articles. MB was associated with major adverse cardiac events - OR = 1.52 (1.01–2.30), and myocardial ischemia OR = 3.00 (1.02–8.82) but not with acute myocardial infarction, cardiovascular death, ischemia identified using imaging techniques, or positive exercise stress testing. Overall, myocardial bridging may have significant cardiovascular consequences (MACE, myocardial ischemia). More studies are needed to reveal/refute a clear association with MI, sudden death or other cardiovascular pathologies.

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.

Assessment of Myocardial Bridge by Cardiac CT: Intracoronary Transluminal Attenuation Gradient Derived from Diastolic Phase Predicts Systolic Compression

Objective

To study the predictive value of transluminal attenuation gradient (TAG) derived from diastolic phase of coronary computed tomography angiography (CCTA) for identifying systolic compression of myocardial bridge (MB).

Materials and Methods

Consecutive patients diagnosed with MB based on CCTA findings and without obstructive coronary artery disease were retrospectively enrolled. In total, 143 patients with 144 MBs were included in the study. Patients were classified into three groups: without systolic compression, with systolic compression < 50%, and with systolic compression ≥ 50%. TAG was defined as the linear regression coefficient between intraluminal attenuation in Hounsfield units (HU) and length from the vessel ostium. Other indices such as the length and depth of the MB were also recorded.

Results

TAG was the lowest in MB patients with systolic compression ≥ 50% (-19.9 ± 8.7 HU/10 mm). Receiver operating characteristic curve analysis was performed to determine the optimal cutoff values for identifying systolic compression ≥ 50%. The result indicated an optimal cutoff value of TAG as -18.8 HU/10 mm (area under curve = 0.778, p < 0.001), which yielded higher sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy (54.1, 80.5, 72.8, and 75.0%, respectively). In addition, the TAG of MB with diastolic compression was significantly lower than the TAG of MB without diastolic compression (-21.4 ± 4.8 HU/10 mm vs. -12.7 ± 8 HU/10 mm, p < 0.001).

Conclusion

TAG was a better predictor of MB with systolic compression ≥ 50%, compared to the length or depth of the MB. The TAG of MB with persistent diastolic compression was significantly lower than the TAG without diastolic compression.

Myocardial bridging: a review with emphasis on electrocardiographic findings

BACKGROUND

Myocardial bridging (MB) occurs when a segment of an epicardial coronary artery takes an intra- myocardial course, thus leading to systolic compression. Most myocardial bridges involve the left anterior descending artery and are observed in 14-35% of patients. Different pathophysiological mechanisms can induce symptoms secondary to myocardial ischemia: systolic coronary compression, diastolic dysfunction associated with aging and coronary atherosclerosis, LV hypertrophy, vasospasm, microvascular and endothelial dysfunction, plaque development proximal to the bridge.

METHODS

We performed a literature review of MB, with a particular emphasis on electrocardiographic manifestations.

RESULTS

Stable angina-like chest pain is the usual presentation and MB should be suspected in patients at low risk for coronary atherosclerosis which refer this symptom or which present myocardial ischemia at instrumental examinations. ECG changes are not specific for MB and resting ECG is often normal or presents ST segment anomalies. Exercise stress test often shows non specific signs of ischemia, conduction disturbances or arrhythmias which do not allow the distinction between myocardial bridging and other causes of myocardial ischemia; angina often appears during exercise, even in the absence of ECG changes. Myocardial perfusion deficits at scintigraphy are neither obligatory nor specific. Although the clinical significance of MB is still debated, MB has been associated with acute coronary syndrome, coronary vasospasm, and even sudden cardiac death.

CONCLUSION

Although MB may lead to myocardial ischemia during stress, its clinical presentation and electrocardiographic findings are not specific.

Elevated troponin levels in previously healthy children: value of diagnostic modalities and the importance of a drug screen

BACKGROUND

Myocardial injury in previously healthy children is rare, with a wide range of aetiologies. It is increasingly being identified on the basis of elevated troponin levels during routine evaluation of cardiorespiratory symptoms. Establishing the aetiology remains challenging because of the lack of an accepted work-up algorithm. Our objective was to delineate the contribution of diagnostic modalities and troponin patterns towards the final diagnosis.

METHODS

A retrospective chart review of previously healthy patients admitted to the Pediatric Cardiology Service with myocardial injury was carried out. Data analysed included echocardiograms, electrocardiograms, cardiac catheterisations, magnetic resonance imaging, drug screen tests, troponin values, and final diagnosis.

RESULTS

A total of 32 patients were identified. The diagnoses were: myocarditis in 16 patients, vasospasm due to drug use in seven, myopericarditis in six, anomalous coronary artery origins in two, and Prinzmetal's angina in one patient. The electrocardiograms were abnormal in 27 of the 32 patients (84%), echocardiograms in 18 of the 32 patients (56%), cardiac magnetic resonance imaging in two of the four patients (50%), urine drug screen in five of the 25 patients (20%), and cardiac catheterisations in two of the 15 patients (13%).

CONCLUSIONS

Myocarditis is the most common aetiology of myocardial injury in children. Clinical history remains the basic screening tool; drug screens help identify coronary vasospasms secondary to drug use (22% of our cohort). Patients with anomalous coronaries had exertional symptoms. Initial troponin levels and progression were not diagnostic or prognostic. Catheterisation is of limited value and did not change management. Magnetic resonance imaging with gadolinium enhancement is probably the most useful test when initial evaluation is not diagnostic.

Association of variance in anatomical elements of myocardial bridge with coronary atherosclerosis

OBJECTIVES

The myocardial bridge (MB) is an anatomical structure consisting of myocardium covering a part of the left anterior descending coronary artery (LAD). The extent and spatial distribution of atherosclerosis in the LAD with an MB is influenced by the anatomical properties of the MB. In this study, the relationship between the overall anatomical framework of the MB including the periarterial adipose tissue as well as fibrosis of the MB itself and coronary atherosclerosis was histomorphometrically examined.

METHODS

Full-length LADs with an MB from 180 autopsied hearts were cross-sectioned at 5-mm intervals. Together with measurements of MB - length, thickness, and location, proportional decrease of the atherosclerosis ratio of LAD segments beneath MB for that of LAD segments proximal to MB was defined as the atherosclerosis suppression ratio. The area ratio of adipose tissue in the periarterial area beneath MB and area ratio of fibrosis in the MB muscle were also measured.

RESULTS

The atherosclerosis suppression ratio was significantly proportional to MB length and thickness. Periarterial adipose tissue beneath MB was detected in all cases (100%), and fibrosis within MB muscle for 136 cases (75.6%). The amount of adipose tissue beneath MB and MB fibrosis did not statistically affect the atherosclerosis suppression ratio. Multivariate analysis revealed MB length and thickness were the independent factors affecting the atherosclerosis suppression ratio.

CONCLUSIONS

The anatomical properties of an MB, especially of its length and thickness, play decisive roles as regulators of atherosclerosis in the LAD regardless of the amount of adipose tissue around LAD and MB fibrosis.

Increase in mean platelet volume in patients with myocardial bridge

AIM

Myocardial bridge is associated with atherosclerosis altered in shear stress and endothelial dysfunction. Mean platelet volume (MPV), a determinant of platelet activation, is shown to be related with atherosclerosis and endothelial dysfunction. In this study, we aimed to evaluate platelet function assessed by MPV in patients with myocardial bridge.

METHODS

Forty-two patients with myocardial bridge in the left anterior descending artery (LAD) and 43 age- and gender-matched healthy participants were included in the study. Myocardial bridging was defined as an intramyocardial systolic compression or milking of a segment of an epicardial coronary artery on angiography. For the entire study population, MPV was measured using an automatic blood counter.

RESULTS

The study population consisted of 42 patients with myocardial bridge (52.7 ± 10.2, 76.2% male) and 43 age- and sex-matched healthy control participants (52.1 ± 10.4, 74.4% male). Compared to the control group, MPV value was significantly higher in patients with myocardial bridge (8.9 ± 1.24 vs 8.3 ± 0.78; P = .01). Further, there were no significant differences between groups regarding hemoglobin level, platelet count, fasting blood glucose, and creatinine levels.

CONCLUSIONS

Our study findings indicated that myocardial bridge is associated with elevated MPV values. Our results might partly explain the increased cardiovascular events in patients with myocardial bridge.

The role of myocardial perfusion imaging in evaluating patients with myocardial bridging

BACKGROUND

Myocardial bridging (MB) is a common, congenital coronary-abnormality that is found on average in one out of every three adults at autopsy (Moehlenkamp et al in Circulation, 106:2616-2622, 2002; Erbel et al in Circulation, 120:357-359, 2009). However, its clinical significance and impact on myocardial ischemia remains controversial and unclear. Myocardial perfusion imaging (MPI) is widely used to assess myocardial ischemia in patients with known or suspected coronary artery disease, and is frequently performed to evaluate the hemodynamic significance of MB. This study was undertaken to determine the use of MPI in evaluating MB and to identify the characteristics of MB associated with perfusion defects using MPI.

METHODS AND RESULTS

Thirty-nine patients with MB of the left anterior descending (LAD) artery as documented by coronary angiography (CA) were enrolled for this study. None of the patients exhibited other forms of heart disease as determined by both CA and stress-rest MPI, no later than 1 month prior to the study. Using MPI, eight patients (20.5%) were found to have perfusion defects in the corresponding myocardial areas. This frequency was significantly higher when compared with results obtained by stress electrocardiogram. The difference in the mean systolic narrowing of bridging segments was statistically significant between patients with and without ischemia. The positive rate of reversible defects in patients with severe systolic narrowing was significantly higher than in patients with mild-to-moderate systolic narrowing. However, there was no significant difference either between the mean length of the tunneled artery in patients with and without abnormal MPI or the positive rate of abnormal MPI in patients with different locations of the tunneled artery.

CONCLUSIONS

MPI is an effective, noninvasive technique for the evaluation of patients with MB. The myocardial ischemia that resulted from bridging is associated more closely with the degree of systolic narrowing than with the length of tunneled artery or the location of MB.

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.