Systolic luminal narrowing and morphologic characteristics of myocardial bridging of the mid-left anterior descending coronary artery by dual-source computed tomography

The effects of myocardial bridging on two-dimensional myocardial strain during dobutamine stress echocardiography

Myocardial bridging (MB) is a common anatomic variant in coronary arteries with unclear functional significance. We evaluated regional myocardial strain by speckle tracking during dobutamine stress echocardiography (DSE) in patients with MB in the left anterior descending coronary artery (LAD). We studied 11 patients with MB in the LAD and no obstructive coronary artery disease (CAD), 7 patients without MB, but obstructive CAD in the LAD, and 12 controls without MB or obstructive CAD. MB was defined as either > 1 mm (superficial) or > 2 mm (deep) intramyocardial course of the LAD in coronary CT angiography. Regional longitudinal, radial and circumferential strains and strain rates as well as post-systolic strain index (PSI) were measured at rest, peak stress, and early recovery (1 min after stress). Strain parameters during DSE were similar in the myocardium distal to MB and other myocardial regions of the same patients as well as the LAD territory in controls. However, patients with obstructive CAD showed impaired LS and strain rate as well as increased PSI at peak stress. None of the MB was associated with systolic compression in invasive coronary angiography and strain parameters were similar between superficial and deep MB. Stress myocardial blood flow by positron emission tomography correlated with LS and RS at peak stress in the myocardium distal to MB (r = - 0.73, p = 0.03, and r = 0.64, p = 0.04, respectively). Myocardial strain is not reduced during DSE in patients with MB in the LAD and no significant systolic compression.

Effect of Intramural Course of Coronary Arteries Assessed by Computed Tomography Angiography in Patients With Hypertrophic Cardiomyopathy

This study evaluated the prevalence, anatomical pattern, and prognostic implications of an intramural course of the coronary arteries in patients with hypertrophic cardiomyopathy (HC). The study population consisted of 92 patients with HC and 100 patients without HC. The presence of an intramural course of the coronary arteries was evaluated by coronary computed tomography angiography (CTA), and its length and depth were measured. During follow-up, the occurrence of unstable angina requiring hospitalization, myocardial infarction, and all-cause mortality was evaluated. An intramural course of the coronary arteries was more common in patients with HC than patients without HC (62% vs 25%, p <0.001). In the patients with an intramural coronary artery course, those with HC had a longer course (29.1 ± 15.3 mm vs 23.0 ± 13.0 mm; p = 0.037) with deeper penetration into the left ventricular myocardium (2.8 ± 1.2 mm vs 2.1 ± 0.8 mm; p = 0.007) and more involvement of multiple coronary arteries (38% vs 4%; p <0.001). During follow-up (mean 5.5 ± 3.5 years), cardiac events occurred in 17 of 57 patients (29.8%) with an intramural course and 11 of 35 (31.4%) without an intramural course (p = 0.87). On Kaplan-Meier survival analysis, there was no difference in cumulative event rate between HC patients with or without an intramural course (p = 0.89, log rank test). In conclusion, patients with HC have a high rate of an intramural course of the coronary arteries on CTA. The number of involved arteries and the length and depth of the intramural course differ between patients with and without HC, but apparently have no association with worse clinical outcomes.

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.

Measurements of myocardial bridges on computed tomography predict presence of clinical symptoms and outcomes of adverse heart events: a retrospective study in a large population from China

Background Clinical-radiological correlation of myocardial bridge (MB) remains unclear. Purpose To correlate clinical symptoms and outcomes of MBs with computed tomography (CT) coronary angiography findings. Material and Methods A total of 2092 patients with CT coronary angiography were collected. Patients were divided into symptomatic and asymptomatic groups, adverse heart events (AHE) and non-AHE groups, MB and non-MB groups, as well as left anterior descending (LAD)-MB and non-LAD-MB groups. Statistical analyses were performed to identify inter-group differences, and clinical-radiological correlations of MBs or mural coronary arteries (MCAs). Results The prevalence of MB, the MCA stenosis either in systole or in diastole, and the ratio of LAD-MB were significantly higher in the symptomatic group than in the asymptomatic group, and higher in the AHE group than in the non-AHE group ( P all <0.05). MB thickness, systolic MCA stenosis, and diastolic MCA stenosis were independent variables predicting clinical symptoms ( P < 0.05), with diastolic MCA stenosis having the highest diagnostic performance, when cutting at 24.6%. The corresponding sensitivity and specificity were 87.8% and 90.6%, respectively. Diastolic MCA stenosis independently indicated outcome of AHE (odds ratio, 1.047; P < 0.001). Conclusion Measurements of MB-MCA by CT predict the presence of clinical symptoms and outcomes of AHE, with diastolic MCA stenosis possessing the greatest performance.

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.

Systolic Compression of a Myocardial Bridged Coronary Artery and its Morphologic Characteristics: A Combination Study of Computed Tomography Angiography and Invasive Angiography

Background

Myocardial bridging (MB) is a congenital anomaly in which a segment of a major epicardial coronary artery courses through the myocardium. This anomaly can lead to myocardial ischemia, arrhythmia, and even death. The effectiveness of coronary computed tomographic angiography (CCTA) in the detection of MB and its morphological features, and the accuracy of invasive coronary angiography (ICA) in the evaluation of systolic compression have been shown in some prior studies.

Objectives

The present study aimed to evaluate the correlation between the depth and the length of MB as determined using CCTA, and the degree of luminal narrowing of the involved tunneled segment as calculated using the ICA.

Patients and Methods

For this study, 109 consecutive patients diagnosed with myocardial bridging using CCTA, and who had already undergone ICA, were studied. The depth and length of the MB was determined in the CCTA, while the degree of systolic compression was calculated in the ICA. The correlation between the depth and length of the MB and the systolic compression were then evaluated.

Results

The degree of systolic compression was found to be correlated with the depth of the MB. However, there was no correlation between the length of the MB and the degree of systolic compression.

Conclusion

The systolic compression of the MB was influenced by the depth of the tunneled segment, not by its length.

Sudden cardiac death from structural heart diseases in adults: imaging findings with cardiovascular computed tomography and magnetic resonance

Sudden cardiac death (SCD) is defined as the unexpected natural death from a cardiac cause within an hour of the onset of symptoms in the absence of any other cause. Although such a rapid course of death is mainly attributed to a cardiac arrhythmia, identification of structural heart disease by cardiovascular computed tomography (CCT) and cardiovascular magnetic resonance (CMR) imaging is important to predict the long-term risk of SCD. In adults, SCD most commonly results from coronary artery diseases, coronary artery anomalies, inherited cardiomyopathies, valvular heart diseases, myocarditis, and aortic dissection with coronary artery involvement or acute aortic regurgitation. This review describes the CCT and CMR findings of structural heart diseases related to SCD, which are essential for radiologists to diagnose or predict.

Multimodality Imaging in the Assessment of the Physiological Significance of Myocardial Bridging

In myocardial bridging (MB) a segment of the coronary artery is covered by the myocardium. MB can be seen as a systolic compression by invasive coronary angiography (ICA) or as an intramural course by computed tomography angiography (CTA). Intramural course is a common incidental finding in CTA studies. Only minority of the bridging segments are associated with systolic compression causing a possible impairment of myocardial perfusion. The relationship between myocardial blood flow and MB is complex and poorly evaluated by anatomic imaging. Furthermore, provocation tests are frequently needed to uncover systolic compression. Fractional flow reserve can be used to assess the hemodynamic significance of MB. Nuclear perfusion imaging can demonstrate flow abnormalities associated with MB. Stress echocardiography can demonstrate ischemic wall motion abnormalities. They can be complemented by hybrid imaging with CTA to distinguish epicardial coronary artery disease and MB. This article will review different imaging modalities for the evaluation of the physiologic significance of MB.

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.

Myocardial bridging: what have we learned in the past and will new diagnostic modalities provide new insights?

The clinical significance of myocardial bridging has been a subject of discussion and controversy since the introduction of coronary arteriography (CAG) in the early 1960s. More recently computed tomography coronary angiography (CTCA) has made it possible to visualise the overlying muscular bands and appears to have a higher sensitivity for detecting myocardial bridging than CAG. Combining CTCA with invasive techniques such as CAG should make it possible to improve our understanding of the pathophysiology of myocardial bridging and to provide answers to hitherto unresolved questions. This paper critically reviews the outcomes of previous studies and defines remaining questions that should be answered to optimise the management of the presumably fast growing number of patients in whom a diagnosis of myocardial bridging has been made.