Impact of Diastolic Vessel Restriction on Quality of Life in Symptomatic Myocardial Bridging Patients Treated With Surgical Unroofing: Preoperative Assessments With Intravascular Ultrasound and Coronary Computed Tomography Angiography

Comparison of Coronary Physiological Indices in Identifying Functionally Significant Myocardial Bridges in ANOCA

BACKGROUND

A functionally significant myocardial bridge (MB) is an important cause of angina with nonobstructive coronary arteries. However, distinguishing a functionally significant versus incidental MB remains challenging. Resting and hyperemic intracoronary functional indices are available, but no studies have compared their diagnostic performance in MBs.

METHODS

We prospectively studied 64 patients with angina and nonobstructive coronary arteries, all of whom had an MB confirmed by intravascular ultrasound. We evaluated the diagnostic performance of instantaneous wave-free ratio (iFR) and resting full-cycle ratio (RFR) under Dobutamine stress, with Dobutamine diastolic fractional flow reserve (dFFR) as a reference standard. Dobutamine iFR and Dobutamine RFR were assessed in the first 18 patients, while only Dobutamine RFR was assessed in the remaining 46. Dobutamine dFFR ≤0.76 was considered indicative of a functionally significant MB.

RESULTS

There was a strong correlation between Dobutamine iFR (R2=0.67, P<0.001) and Dobutamine RFR (R2=0.80, P<0.001) with Dobutamine dFFR. Receiver operating characteristics curve analysis to identify the cutoff for Dobutamine dFFR ≤0.76 was 0.81 for Dobutamine iFR (area under the curve 0.961) and 0.76 for Dobutamine RFR (area under the curve 0.996). The diagnostic accuracy of Dobutamine iFR was 94.4%, with a sensitivity of 100% and specificity of 85.7%. For Dobutamine RFR, the diagnostic accuracy was 96.9%, with a sensitivity of 95.8% and specificity of 100%.

CONCLUSIONS

In patients with angina and nonobstructive coronary arteries and an MB confirmed by intravascular ultrasound, Dobutamine iFR and Dobutamine RFR may serve as alternatives to Dobutamine dFFR in identifying a functionally significant MB, with Dobutamine RFR having superior diagnostic accuracy.

Optimal Medical Therapy for Stable Ischemic Heart Disease: Focus on Anti-anginal Therapy

Chronic coronary disease (CCD) is a major cause of morbidity and mortality worldwide. The most common symptom of CCD is exertional angina pectoris, a discomfort in the chest that commonly occurs during activities of daily life. Patients are dismayed by recurring episodes of angina and seek medical help in preventing or minimizing episodes. Angina occurs when the coronary arteries are unable to supply sufficient blood flow to the cardiac muscle to meet the metabolic needs of the left ventricular myocardium. While lifestyle changes and aggressive risk factor modification play a critical role in the management of CCD, management of angina usually requires pharmacologic therapy. Medications such as beta-blockers, calcium channel blockers, nitrates, ranolazine, and others ultimately work to improve the mismatch between myocardial blood flow and metabolic demand. This manuscript briefly describes the pathophysiologic basis for symptoms of angina, and how currently available anti-anginal therapies contribute to preventing or minimize the occurrence of angina.

Presence and Relevance of Myocardial Bridge in LAD-PCI of CTO and Non-CTO Lesions

BACKGROUND

Intravascular ultrasound (IVUS) studies show that one-quarter of left anterior descending (LAD) arteries have a myocardial bridge. An MB may be associated with stent failure when the stent extends into the MB.

OBJECTIVES

The aim of this study was to investigate: 1) the association between an MB and chronic total occlusion (CTO) in any LAD lesions; and 2) the association between an MB and subsequent clinical outcomes after percutaneous coronary intervention in LAD CTOs.

METHODS

A total of 3,342 LAD lesions with IVUS-guided percutaneous coronary intervention (280 CTO and 3,062 non-CTO lesions) were included. The primary outcome was target lesion failure (cardiac death, target vessel myocardial infarction, definite stent thrombosis, and ischemic-driven target lesion revascularization).

RESULTS

An MB by IVUS was significantly more prevalent in LAD CTOs than LAD non-CTOs (40.4% [113/280] vs 25.8% [789/3,062]; P < 0.0001). The discrepancy in CTO length between angiography and IVUS was greater in 113 LAD CTOs with an MB than 167 LAD CTOs without an MB (6.0 [Q1, Q3: 0.1, 12.2] mm vs 0.2 [Q1, Q3: -1.4, 8.4] mm; P < 0.0001). Overall, 48.7% (55/113) of LAD CTOs had a stent that extended into an MB after which target lesion failure was significantly higher compared to a stent that did not extend into an MB (26.3% vs 0%; P = 0.0004) or compared to an LAD CTO without an MB (26.3% vs 9.6%; P = 0.02).

CONCLUSIONS

An MB was more common in LAD CTO than non-CTO LAD lesions. If present, approximately one-half of LAD CTOs had a stent extending into an MB that, in turn, was associated with worse outcomes.

Myocardial Bridging: Review on the Role of Coronary Computed Tomography Angiography

Myocardial bridging (MB) is a congenital coronary anomaly in which a segment of a coronary artery, most frequently the left anterior descending artery, deviates from its epicardial route by passing through the myocardium. The advent of cardiac computed tomography angiography (CCTA), equipped with its multiplane and three-dimensional functionalities, has notably enhanced the ability to identify MBs. Furthermore, novel post-processing methods have recently emerged to extract functional insights from anatomical evaluations. MB is generally considered a benign entity with very good survival rates; however, there is an increasing volume of evidence that certain MB characteristics may be associated with cardiovascular morbidity. This review is intended to depict the diagnostic and prognostic role of CCTA in the MB context.

Nomogram to predict recurrent chest pain in patients with myocardial bridging

OBJECTIVE

Patients with myocardial bridging (MB) frequently experience recurrent chest pain, even in those without coronary heart disease. This study aims to predict the risk of recurrent chest pain in patients with MB by using a novel predictive nomogram.

METHODS

This retrospective study enrolled 250 patients with acute chest pain who underwent coronary computed tomography angiography (CCTA) between January and December 2018, including 111 patients with MB and 139 control patients. Least absolute shrinkage and selection operator (LASSO) and multivariable Cox regression analyses were used to screen for significant parameters that were included to develop a novel predictive nomogram model. Receiver operating characteristic curve, calibration curve, and decision curve analyses were used to evaluate the performance and clinical utility of the nomogram.

RESULTS

A predictive nomogram was constructed in 111 patients with MB, 34 of whom (30.9%) had recurrent chest pain. The significant predictors screened out by the LASSO regression included age, sex, branch type MB, and systolic compression index. The area under the curves (AUCs) for recurrent chest pain at 12, 24, and 36 months were 0.688, 0.742, and 0.729, respectively, indicating remarkable accuracy of the nomogram. The calibration curve and decision curve analyses indicated a good agreement with the observations and utility of the nomogram.

CONCLUSIONS

This study presents a high-accuracy nomogram to predict recurrent chest pain in patients with MB. This model incorporates clinical risk factors and CT imaging features and can be conveniently used to facilitate the individualised prediction.

KEY POINTS

• Symptomatic patients with myocardial bridging often present with recurrent chest pain. • The potential predictors of recurrent chest pain in patients with myocardial bridging were age, sex, branch type MB, and systolic compression index. • Nomogram based on clinical CT imaging features is valuable to predict recurrent chest pain in patients with myocardial bridging.

Impact of myocardial bridging on coronary artery plaque formation and long-term mortality after heart transplantation

OBJECTIVES

This study aimed to explore the impact of myocardial bridging (MB) on early development of cardiac allograft vasculopathy and long-term graft survival after heart transplantation.

BACKGROUND

MB has been reported to be associated with acceleration of proximal plaque development and endothelial dysfunction in native coronary atherosclerosis. However, its clinical significance in heart transplantation remains unclear.

METHODS

In 103 heart-transplant recipients, serial (baseline and 1-year post-transplant) volumetric intravascular ultrasound (IVUS) analyses were performed in the first 50 mm of the left anterior descending (LAD) artery. Standard IVUS indices were evaluated in 3 equally divided LAD segments (proximal, middle, and distal segments). MB was defined by IVUS as an echolucent muscular band lying on top of the artery. The primary endpoint was death or re-transplantation, assessed for up to 12.2 years (median follow-up: 4.7 years).

RESULTS

IVUS identified MB in 62% of the study population. At baseline, MB patients had smaller intimal volume in the distal LAD than non-MB patients (p = 0.002). During the first year, vessel volume decreased diffusely irrespective of the presence of MB. Intimal growth diffusely distributed in non-MB patients, whereas MB patients demonstrated significantly augmented intimal formation in the proximal LAD. Kaplan-Meier analysis revealed significantly lower event-free survival in patients with versus without MB (log-rank p = 0.02). In multivariate analysis, the presence of MB was independently associated with late adverse events [hazard ratio 5.1 (1.6-22.2)].

CONCLUSION

MB appears to relate to accelerated proximal intimal growth and reduced long-term survival in heart-transplant recipients.

Clinical Implication and Optimal Management of Myocardial Bridging: Role of Cardiovascular Imaging

Myocardial bridging (MB) was historically considered a benign structure as most people with MB are clinically asymptomatic. Recently, however, mounting evidence indicates that MB can cause adverse cardiac events owing to arterial systolic compression/diastolic restriction, atherosclerotic plaque progression upstream from MB, and/or vasospastic angina. In MB patients with refractory angina, the optimal treatment strategy should be determined individually based on versatile anatomic and hemodynamical assessments that often require multidisciplinary diagnostic approaches. The present review summarizes the clinical implication and management of MB, highlighting the role of imaging modalities currently available in this arena.