Relationship Between Myocardial Bridging and Coronary Arteriosclerosis

Comparison of Framingham risk score and atherogenic indices as a predictor of atherosclerosis in patients with myocardial bridge in left anterior descending artery

BACKGROUND

Myocardial bridge (MB) is generally considered as a benign condition, but it may trigger atherosclerosis, especially in the adjacent proximal coronary artery segment. In this study, we aimed to investigate whether the Framingham risk score (FRS) or atherogenic indices are risk factors for coronary atherosclerosis in patients with MB in the left anterior descending coronary artery (LAD).

METHODS

We performed a retrospective study evaluating 155 patients who have MB in LAD. The patients were evaluated in two groups according to the presence of atherosclerosis (74 patients in atherosclerotic group vs. 81 patients in non-atherosclerotic group). Baseline characteristics, FRS and atherogenic indices were reviewed between groups. Significant independent risk factors for coronary atherosclerosis were investigated by logistic regression analysis.

RESULTS

Patients in atherosclerotic group were significantly older (58.15 ± 10.04 vs. 50.22 ± 9.27 years, p < .001) and 74.3% of the patients were male. While the mean FRS in the atherosclerotic group was 21.20 ± 8.81, it was 12.79 ± 8.61 in the non-atherosclerotic group (p < .001). Among the atherogenic indices, only LDL-c/HDL-c ratio was significantly higher in the atherosclerotic group (3.49 ± 1.2 vs. 3.11 ± 0.98, p:.033). Multivariable analysis showed that age (OR: 1.08, 95% CI 1.03-1.13, p < .001) and FRS (OR: 1.06, 95% CI 1.01-1.11, p:.012) were independently associated with the presence of atherosclerotic lesion.

CONCLUSIONS

FRS is an easily applicable predictor in clinical practice that indicates the presence of coronary atherosclerosis in patients with MB in LAD.

Implications of Myocardial Bridge on Coronary Atherosclerosis and Survival

Background: In this study, we aimed to describe the impact of MBs on atherosclerosis and survival, in patients with coronary artery disease (CAD). Methods: We retrospectively studied 1920 consecutive patients who underwent conventional coronary angiography for suspected CAD. Atherosclerotic load (AL), defined as the sum of degrees of stenosis, and general atherosclerotic load (GAL), representing the sum of AL, were compared between patients with MB and a control group without MB; patients in these groups were similar in age and sex. We assessed survival at 10 years after the last enrolled patient. Results: Prevalence of MB was 3.96%, predominantly in the mid-segment of left anterior descendent artery (LAD). In the presence of MB, GAL was lower (158.1 ± 93.7 vs. 205.3 ± 117.9, p = 0.004) with a lesser AL in the proximal (30.3 ± 39.9 vs. 42.9 ± 41.1, p = 0.038) and mid-segments (8.1 ± 20.0 vs. 25.3 ± 35.9, p < 0.001) of LAD. Based on a Multinominal Logistic Regression, we found that the presence of MB on LAD (regardless of its location on this artery) is a protective factor against atherosclerotic lesions, decreasing the probability of significant stenosis, especially of those ≥70%, on the entire artery (B −1.539, OR 4660; 95% CI = 1.873−11.595, p = 0.001) and on each of its segments as well: proximal LAD (B −1.275, OR 0.280; 95% CI = 0.015−5.073; p = 0.038), mid-LAD (B −1.879, OR 6.545; 95% CI = 1.492−28.712; p = 0.013) and distal LAD (B −0.900, OR 2.459, 95% CI = 2.459−2.459, p = 0.032). However, 10-year survival was similar between groups (76.70% vs. 74.30%, p = 0.740). Conclusion: The presence of MB on LAD proved to be a protective factor against atherosclerosis for the entire artery and for each of its segments, but it does not influence long-term survival in patients with CAD.

A Case of Syncope in a Child due to the Large Segment of Myocardial Bridge

We report a child with an unusual coronary bridge crossing over the left anterior descending (LAD), circumflex (CX), and right coronary artery (RCA). The bridges range from 0.8-1.2 mm depth. The patient presented with exercise-induced syncope and myocardial infarction (MI). She exhibited no syncope after medicine and exercise control.

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 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.

An Updated Review on Myocardial Bridging

Myocardial bridging is a congenital coronary anomaly with normal epicardial coronary artery taking an intra-myocardial course also described as tunneled artery. The majority of patients with this coronary anomaly are asymptomatic and generally it is a benign condition. However, it is an important cause of myocardial ischemia, which may lead to anginal symptoms, acute coronary syndrome, cardiac arrhythmias and rarely sudden cardiac death. There are numerous studies published in the recent past on understanding the pathophysiology, diagnostic and management strategies of myocardial bridging. This review highlights some of the recent updates in the diagnosis and management of patients with myocardial bridging. We discuss the role of various non-invasive and invasive diagnostic methods to evaluate functional significance of bridging. In addition, role of medical therapy such as beta-blockers, percutaneous coronary intervention with stents/bioresorbable scaffolds and surgical unroofing in patients unresponsive to medical therapy is highlighted as well.

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.

Integrated microRNA‑gene analysis of coronary artery disease based on miRNA and gene expression profiles

The present study aimed to investigate the key genes and microRNAs (miRNA/miRs) associated with coronary artery disease (CAD) progression. The gene expression profile of GSE20680 and GSE12288, and the miRNA expression profile of GSE28858 were downloaded from the gene expression omnibus database. The differentially expressed genes (DEGs) in GSE20680 and GSE12288, and the differentially expressed miRNAs in GSE28858 were screened using the limma package in R software. Common DEGs between GSE20680 and GSE12288 were selected. Functions and pathways of DEGs and miRNAs were enriched using the DAVID tool from the GO and KEGG databases. The regulatory network of miRNA and selected CAD-associated DEGs was constructed. A total of 270 DEGs (167 upregulated and 103 downregulated) based on the GSE20680 dataset, and 2,268 DEGs (534 upregulated and 1,734 downregulated) based on the GSE12288 dataset, were screened. For the differentially expressed miRNAs, 214 were identified (102 upregulated and 112 downregulated) in CAD samples and were screened. Interferon regulatory factor 2 (IRF2) and cell death-inducing DFFA-like effector b (CIDEB), which are regulated by signal transducer and activator of transcription 3 and myc-associated factor X, were identified as common DEGs for CAD. miR-455-5p, miR-455-3p and miR-1257, which are involved in the major histocompatibility complex (MHC)protein assembly pathway and peptide antigen assembly with MHC class I protein complex pathway, may regulate various miRNAs and target genes, including pro-opiomelancortin (POMC), toll-like receptor 4 (TLR4), interleukin 10 (IL10), activating transcription factor 6 (ATF6) and calreticulin (CALR). The current study identified IRF2 and CIDEB as crucial genes, and miRNA-455-5p, miRNA-455-3p and miR-1257 along with their target genes POMC, TLR4 and CALR, as miRNAs involved in CAD progression. Thus, the present study may provide a basis for future research into the progression mechanism of CAD.

Incremental diagnostic value of epicardial adipose tissue for the detection of functionally relevant coronary artery disease

BACKGROUND AND AIM

To determine the incremental diagnostic value of epicardial adipose tissue (EAT) volume in addition to the coronary artery calcium (CAC) score for detecting hemodynamic significant coronary artery disease (CAD).

METHODS AND RESULTS

122 patients (mean age 61 ± 10 years, 61% male) without a previous cardiac history underwent a non-contrast CT scan for calcium scoring and EAT volume measurements. Subsequently all patients underwent invasive coronary angiography (ICA) in conjunction with fractional flow reserve (FFR) measurements. A stenosis >90% and/or a FFR ≤0.80 were considered significant. Mean EAT volume and CACscore were 128 ± 51 cm(3) and 418 ± 704, respectively. The correlation between EAT volume and the CACscore was poor (r = 0.11, p = 0.24). Male gender (odds ratio [OR] 2.86, p = 0.01), CACscore ([cut-off value 100] OR 3.31, p = 0.003, and EAT volume ([cut-off value 92 cm(3)] OR 4.28, p = 0.01) were associated with flow-limiting disease. The multivariate model revealed that only male gender (OR 2.50, p = 0.045), CAC score (OR 3.60, p = 0.005), and EAT volume (OR 4.95, p = 0.02) were independent predictors of myocardial ischemia. Using the cut-off values of 100 (CAC score) and 92 cm(3) (EAT volume), sensitivity, specificity, negative predictive value, positive predictive value, and accuracy for detecting functionally relevant CAD as indicated by FFR were 71, 57, 77, 50 and 63% and 91, 29, 85, 44 and 52% for the CACscore and EAT volume, respectively. Adding EAT volume to the CAC score and cardiovascular risk factors did not enhance diagnostic performance for the detection of significant CAD (p = 0.57).

CONCLUSION

EAT volume measurements have no diagnostic value beyond calcium scoring and cardiovascular risk factors in the detection of hemodynamic significant CAD.