Detection of myocardial bridge by optical coherence tomography

Abstract Background Optical coherence tomography (OCT) findings of myocardial bridge (MB) have not been established. Purpose We aimed to establish the OCT appearance of MB compared with the half-moon sign derived by intravascular ultrasound (IVUS) and to assess the prevalence among patients undergoing coronary angiography and OCT in clinical practice. Methods For derivation of the OCT appearance of MB, imaging data obtained from 122 patients undergoing OCT and IVUS for the left anterior descending artery (LAD) enrolled in two prospective imaging studies were analyzed. To assess the prevalence of OCT-derived MB, 470 patients undergoing OCT for LAD in clinical routine were analyzed. Results We found a homogeneous band with intermediate light intensity surrounding the vessel wall as assessed by OCT corresponding to half-moon sign derived by IVUS. Mean length, angle, and thickness of OCT-MB were 21.2±10.8mm, 205.7±56.5°, and 0.39±0.06mm, respectively. Mean length of IVUS-MB was significantly longer as compared with OCT-MB (23.7±11.9, P=0.010), while there were no significant differences in angle and thickness. MB angle was >180° in approximately 50% of frames with MB. There was a strong/moderate correlation between OCT-MB and half-moon sign (MB length: r=0.81, P=0.001, MB angle: r=0.58, P=0.001). In the derivation cohort, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of OCT-MB for the milking effect by angiography were 96.3%, 62.1%, 41.9%, 98.3%, and 69.7%, respectively, and much comparable with the IVUS half-moon sign. In the validation cohort, OCT-detected MB was observed in 139 (29.6%) patients, of whom 57.6% (n=80) did not have angiographic evidence of milking effect. Conclusion OCT is able to identify IVUS-defined MB as homogenous band with intermediate light intensity surrounding the vessel wall. There was a high concordance in terms of MB angle and thickness between OCT and IVUS. In clinically-indicated OCT cases of the LAD, more than half of OCT-MBs were angiographically silent. OCT assessment of MB may facilitate the accurate diagnosis of MB and thus provide useful information in determining the subsequent treatment strategy for the patients with MB. FUNDunding Acknowledgement Type of funding sources: None. Representative imaging of MB Case of OCT-MB without milking effect

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A case report of a coronary myocardial bridge with impaired full-cycle ratio during dobutamine challenge

European Heart Journal - Case Reports ◽

10.1093/ehjcr/ytaa099 ◽

2020 ◽

Vol 4 (3) ◽

pp. 1-4

Author(s):

Eisuke Usui ◽

Akiko Maehara ◽

Ziad A Ali ◽

Jeffrey W Moses

Keyword(s):

Optical Coherence Tomography ◽

Chest Pain ◽

Cardiac Cycle ◽

Aortic Pressure ◽

Optical Coherence ◽

Myocardial Bridge ◽

Coronary Pressure ◽

Early Diastole ◽

Atherosclerotic Stenosis ◽

Waveform Pattern

Abstract Background A myocardial bridge (MB) is a coronary variant in which an epicardial coronary artery tunnels through the myocardial band. Although MBs have been reported to cause ischaemia, physiological assessment of an MB has not been fully established. Case summary We encountered a case with exertional chest pain who underwent coronary angiography showing an MB at the mid-left anterior descending artery with systolic compression. Optical coherence tomography showed an MB defined as a homogeneous intermediate intensity surrounding the epicardial artery. The full-cycle ratio, defined as the lowest ratio of distal coronary pressure (Pd) to aortic pressure (Pa) during the entire cardiac cycle, measured 0.89 at rest and 0.73 with intravenous dobutamine of 20 µg/kg/min with a distinctive waveform pattern (early diastolic Pd drop) during a dobutamine challenge. Metoprolol succinate dosage was increased. The patient has been free from chest pain for 7 months after the discharge. Discussion Optical coherence tomography may contribute to anatomical detections of MBs. Because a systolic compression of the MB and release of the vascular lumen during early diastole leads to an early steep pressure loss, early diastolic Pd drop should be one of the specific haemodynamic characteristics of MBs. On the other hand, in a severe atherosclerotic stenosis, Pd drop is typically observed in late diastole, which could be differentiated from that of MBs. Because full-cycle ratio reflects the whole cardiac cycle including early diastole, this might be more useful than other physiological indices for detection of MB-related ischaemia induced by a dobutamine challenge.

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