Understanding Myocardial Bridging: A Hidden Cause of Chest Pain and Hypertension

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Understanding Myocardial Bridging: A Hidden Cause of Chest Pain and Hypertension

By SB Lee, MD, PhD

Keywords: Myocardial bridge, LAD artery, coronary CTA, chest pain, hypertension, coronary artery anomaly, angina, ischemia

Introduction

Myocardial bridging (MB) is a congenital coronary anomaly where a segment of a coronary artery tunnels through the myocardium rather than resting on its surface. Although often considered a benign anatomical variant, recent evidence suggests that MB can have significant clinical implications, especially when associated with exertional chest pain, hypertension, and ischemia. This article presents an expert-level review based on a case involving a 64-year-old woman who presented with severe hypertension and chest pain and was ultimately diagnosed with myocardial bridging of the mid-left anterior descending (LAD) artery.

Case Summary

A 64-year-old woman arrived at the emergency department with complaints of severe chest pain and uncontrolled hypertension. Initial chest radiography revealed no acute thoracic abnormalities. However, due to the persistence of symptoms, a coronary CT angiography (CTA) was performed.


CTA Findings:

  • A short myocardial bridge segment was noted over the mid-LAD artery, causing up to 50% systolic narrowing.

  • No evidence of atherosclerotic coronary artery disease was observed.

  • There were no calcified or non-calcified plaques, and the myocardial bridge was the sole notable abnormality.

Clinical Significance of Myocardial Bridging

Pathophysiology

In myocardial bridging, a segment of the epicardial coronary artery dips into the myocardium and becomes compressed during systole, leading to transient blood flow limitation. This compression is dynamic and can become pathologically significant, particularly during exercise or stress when coronary demand increases.

Epidemiology

  • Angiographic prevalence: Less than 5%

  • Autopsy-based prevalence: Up to 30%, suggesting a substantial number of asymptomatic cases

  • Frequently found in patients with hypertrophic obstructive cardiomyopathy or heart transplant recipients

Clinical Presentation

Patients with myocardial bridging may be asymptomatic or may present with:

  • Exertional angina

  • Myocardial infarction (MI)

  • Exercise-induced ventricular tachycardia

  • Paroxysmal atrioventricular block

  • Sudden cardiac death (SCD)

Imaging Diagnosis

Coronary CTA is the gold standard non-invasive imaging tool for identifying myocardial bridging (MB). The "milking effect" or systolic narrowing of the tunneled segment is a hallmark finding. Importantly, the proximal segment to the bridged artery may harbor atherosclerotic plaques due to altered hemodynamic shear stress.


The mid-LAD artery is the most commonly involved site, as also observed in our case.

Differential Diagnosis

  • Coronary artery dissection

  • Fixed stenosis from calcified or non-calcified plaque

  • External compression from masses or cardiac anomalies

These must be carefully differentiated via imaging modalities and clinical correlation.

Management Strategy

Medical Management

First-line treatment for symptomatic MB includes:

  • Beta-blockers: Reduce heart rate and systolic compression

  • Calcium channel blockers: Improve coronary vasodilation

Interventional Approaches

In cases refractory to medical therapy:

  • Surgical myotomy: Direct unroofing of the tunneled artery

  • Percutaneous coronary intervention (PCI): Stenting, although controversial due to the risk of stent fracture and in-stent restenosis

Expert Commentary

This case underscores the importance of considering myocardial bridging in the differential diagnosis of unexplained chest pain, particularly when standard evaluations (e.g., ECG, chest X-ray) are unremarkable. While frequently underdiagnosed, MB can lead to serious complications, including arrhythmia and myocardial ischemia.

The role of coronary CTA cannot be overstated in modern cardiology. Its ability to accurately depict both the anatomical course and functional impact of MB makes it indispensable for diagnosis and treatment planning.

Conclusion

Myocardial bridging, while often benign, may present with severe symptoms and mimic more dangerous coronary syndromes. Early recognition via coronary CTA and appropriate management are crucial for preventing adverse cardiac outcomes. Clinicians should maintain a high index of suspicion, especially in hypertensive patients with unexplained chest pain.

References

  1. Alegria JR, Herrmann J, Holmes DR Jr, Lerman A, Rihal CS. Myocardial bridging. Eur Heart J. 2005 Jul;26(12):1159-68. doi:10.1093/eurheartj/ehi203

  2. Corban MT, Hung OY, Eshtehardi P, et al. Myocardial bridging: contemporary understanding of pathophysiology with implications for diagnostic and therapeutic strategies. J Am Coll Cardiol. 2014 Jul 1;63(25 Pt A):2346-55. doi:10.1016/j.jacc.2014.01.049

  3. Lee MS, Chen CH. Myocardial bridging: an up-to-date review. J Invasive Cardiol. 2015 Nov;27(11):521-8.

  4. Möhlenkamp S, Hort W, Ge J, Erbel R. Update on myocardial bridging. Circulation. 2002 Nov 5;106(19):2616-22. doi:10.1161/01.cir.0000039921.60054.21

  5. Tarantini G, Migliore F, Cademartiri F, Fraccaro C, Iliceto S. Left anterior descending artery myocardial bridging: a clinical approach. J Am Coll Cardiol. 2016 Jun 14;67(23):2813-25. doi:10.1016/j.jacc.2016.01.072

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