Treatment of Myocardial Bridge Coronary Arteries
Beta-blockers are the first-line treatment for symptomatic myocardial bridges, with surgery (myotomy and/or coronary bypass) or stenting reserved for refractory cases. 1
Pathophysiology and Clinical Significance
Myocardial bridges consist of muscle fiber bundles overlying an epicardial coronary artery for a variable distance. While the reported incidence at angiography is only 0.5-4.5%, pathological studies reveal a much higher prevalence of 15-85%. The left anterior descending artery is most commonly affected, with typical angiographic presentation showing systolic compression of the artery during the cardiac cycle.
Although most myocardial bridges are benign, they can cause:
- Myocardial ischemia
- Myocardial infarction
- Malignant ventricular arrhythmias
- Atrioventricular block
- Sudden cardiac death (SCD)
Diagnostic Approach
For evaluating the hemodynamic significance of myocardial bridges, the following tests are recommended:
- ECG exercise test
- Dobutamine stress echocardiography
- Myocardial perfusion scintigraphy
In selected cases, functional assessment may require:
- Intracoronary Doppler flow velocity measurement
- Quantitative coronary angiography (which can demonstrate delayed and incomplete vessel diameter gain during mid to late diastole in symptomatic patients)
Treatment Algorithm
First-Line Treatment
- Beta-blockers: These are the mainstay of therapy and are usually effective in improving symptoms 1
- Beta-blockers reduce heart rate, prolong diastole, and decrease contractility, all of which reduce the dynamic obstruction
Second-Line Treatment
- Calcium channel blockers: Alternative when beta-blockers are contraindicated or not tolerated
Important Caution
- Nitrates are contraindicated as they increase the angiographic systolic narrowing and can worsen symptoms 1
For Refractory Cases
When patients remain symptomatic despite optimal medical therapy, consider:
Surgical options:
- Myotomy (surgical unroofing of the bridge)
- Coronary artery bypass grafting (CABG)
Interventional options:
- Percutaneous coronary intervention (PCI) with stenting
- However, these procedures have limitations including risk of coronary perforation and high restenosis rates
Special Considerations
Myocardial bridges occur in 30-50% of patients with hypertrophic cardiomyopathy and have been suggested as a possible cause of sudden cardiac death in these patients 1
Long-term prognosis of isolated myocardial bridges appears to be excellent, but approximately 63% of patients continue to require regular treatment with antianginal drugs 2
The anatomical properties of the myocardial bridge (length, thickness, and location) influence the mechanism of coronary heart disease and should be considered in treatment decisions 3
Monitoring and Follow-up
- Regular clinical follow-up to assess symptom control
- Consider repeat functional testing if symptoms worsen or change in character
- For patients who have undergone interventional procedures, follow standard post-PCI monitoring protocols
By following this treatment algorithm, most patients with symptomatic myocardial bridges can achieve adequate symptom control and maintain a good long-term prognosis.