The Functional Effects of Intramural Course of Coronary Arteries and its Relation to Coronary Atherosclerosis

Uusitalo, Valtteri; Saraste, Antti; Pietilä, Mikko; Kajander, Sami; Bax, Jeroen J.; Knuuti, Juhani

doi:10.1016/j.jcmg.2015.04.001

Cited by 53 publications

(31 citation statements)

References 25 publications

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“…Therefore, Uusitalo et al (8), in this issue of iJACC, Absolute stress perfusion during pharmacological vasodilation was comparable in patients with and without either shallow or deep myocardial bridges. Rest perfusion was higher in patients with myocardial bridges compared to patients without bridges, but absolute stress flow was similar and well above low-flow ischemic levels.…”

Section: The Current Reportmentioning

confidence: 85%

Myocardial Bridges: Lessons in Clinical Coronary Pathophysiology

Gould

Johnson

2015

JACC: Cardiovascular Imaging

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M yocardial perfusion occurs primarily in diastole since systolic contraction transiently impedes coronary blood flow especially to the subendocardium. Thus, myocardial bridges replicate the normal microvascular physiology of high diastolic and low systolic flow, albeit at the level of the epicardial coronary artery. Because marked myocardial bridges are not common during invasive angiography, and hence "abnormal," they have the potential to trigger a similar "oculostenotic" reflex typical for atherosclerotic stenosis. As a relative coronary flow reserve (rel CFR) derived from pressure measurements, fractional flow reserve (FFR) to guide percutaneous coronary intervention has redefined coronary stenosis "severity" from anatomy to physiology, although the journey took 20 years (1,2). Similarly, the severity and effects of myocardial bridges are even more appropriately defined by physiology than anatomy. The physiologic dynamics of myocardial bridges reflect time-varying interactions among aortic pressure, arterial and myocardial compression, diastolic flow, transmural perfusion gradients, heart rate or diastolic perfusion time, and sympathetically driven myocardial contraction and coronary vasoconstriction, all interacting with diffuse and focal atherosclerotic disease that is beyond anatomic description (3-7). THE CURRENT REPORT Therefore, Uusitalo et al. (8), in this issue of iJACC, deserve congratulations for this first systematic study of quantitative perfusion and CFR by positronemission tomography (PET) in adults with myocardial bridging. The protocol included 100 patients with potential coronary artery disease (CAD) undergoing computed tomographic angiography, PET myocardial perfusion imaging at rest and during vasodilator stress, and invasive coronary angiography; 34 of these patients had 48 coronary artery myocardial bridges classified as superficial in 24 (>1-to 2-mm deep) or deep in 24 (>2-mm deep). CAD was assessed by computed tomography soft or calcified plaque, or by quantitative coronary angiography of atherosclerotic percent diameter stenosis. Myocardial bridging was identified by systolic compression of the coronary artery using visual assessment and quantified by quantified coronary angiography of diastolic and systolic angiographic frames.Absolute stress perfusion during pharmacological vasodilation was comparable in patients with and without either shallow or deep myocardial bridges. Rest perfusion was higher in patients with myocardial bridges compared to patients without bridges, but absolute stress flow was similar and well above low-flow ischemic levels. Frequency and severity of CAD by calcium score or percent stenosis was not different among any of the groups and was located primarily proximally to the bridge. Exercise stress tests in these patients were also benign without ischemia related to the myocardial bridges. The authors conclude that myocardial bridging is common but nearly always anatomically and physiologically mild, and not associated with significant flow impairment, myocardi...

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Section: The Current Reportmentioning

confidence: 85%

Myocardial Bridges: Lessons in Clinical Coronary Pathophysiology

Gould

Johnson

2015

JACC: Cardiovascular Imaging

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“…Previous studies have indicated that the extent of MB compression does not necessarily correlate with inducible myocardial ischemia (23), which could partly explain the lower sensitivity value compared to specificity. Furthermore, the potential clinical value of TAG for the assessment of MB lies in the exclusion of significant compression with high specificity, since myocardial perfusion defect was not noted in MB with systolic compression < 50% (24). …”

Section: Discussionmentioning

confidence: 99%

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

Zhang

et al. 2017

Korean J Radiol

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ObjectiveTo 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 MethodsConsecutive 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.ResultsTAG 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).ConclusionTAG 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.

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“…Functional studies validating the effect of the myocardial bridge on the myocardial blood flow demonstrate that its restriction occurs both during the systoles as well as in diastoles, and that there is a link between reversible myocardial ischemia shown by scintigraphy or by the positron emission tomography. 11 Thevasodilator pharmacological stress may not be linked to ischemia because there is no increase in the coronary contractility and subsequent systolic compression. 11 The angiotomography (angio-CT) of the coronaries is an exam that allows viewing the cardiac anatomy, especially that of the coronary arteries, in addition to analyzing the vessel walls, the presence of plaques and the diameter and course of the arteries.…”

Section: Discussionmentioning

confidence: 99%

“…11 Thevasodilator pharmacological stress may not be linked to ischemia because there is no increase in the coronary contractility and subsequent systolic compression. 11 The angiotomography (angio-CT) of the coronaries is an exam that allows viewing the cardiac anatomy, especially that of the coronary arteries, in addition to analyzing the vessel walls, the presence of plaques and the diameter and course of the arteries. Barros and collaborators demonstrated that angio-CT is highly accurate in the morphological evaluation of the myocardial bridge, allowing a noninvasive approach of its localization, length and depth, as well as of the presence of associated atherosclerosis.…”

Section: Discussionmentioning

confidence: 99%