From the Guidelines
Myocardial bridging is usually asymptomatic and of no clinical consequence, but it can rarely be associated with exercise-induced ischemia and exercise-related acute cardiac events, and thus, asymptomatic patients typically require no treatment, while symptomatic patients may benefit from beta-blockers or calcium channel blockers to reduce heart rate and contractility. The condition is diagnosed when a portion of a major epicardial coronary artery is completely covered by myocardium, and it is commonly observed by angiography as coronary artery compression during systole 1. The management of myocardial bridging depends on symptom severity, and for those with symptoms, first-line therapy includes beta-blockers (like metoprolol 25-100mg twice daily) or calcium channel blockers (such as diltiazem 120-360mg daily), which reduce heart rate and contractility, allowing more time for coronary filling during diastole. Some key points to consider in the management of myocardial bridging include:
- Asymptomatic patients typically require no treatment
- Symptomatic patients may benefit from beta-blockers or calcium channel blockers
- Nitrates should be avoided as they can worsen symptoms by increasing heart rate
- In severe cases unresponsive to medication, surgical procedures like myotomy (cutting the muscle bridge) or coronary artery bypass grafting may be considered
- The condition requires careful monitoring, especially in athletes or those with other cardiac risk factors, as increased heart rate and contractility during exercise may exacerbate symptoms 1. Pathological studies suggest that vessels whose tunneled length is long and deeper than 3 mm beneath the epicardium create the greatest vulnerability for cardiac events 1. Myocardial bridging may impair blood flow and may rarely cause myocardial ischemia in a subset of patients, and it is a congenital anomaly whereby a bridge of overlying myocardium causes systolic compression of an epicardial coronary artery that can persist into diastole 1.
From the Research
Definition and Prevalence of Myocardial Bridging
- Myocardial bridging is a congenital coronary anomaly where a segment of coronary artery takes an intra-myocardial course, also described as a tunneled artery 2, 3, 4.
- The majority of patients with this coronary anomaly are asymptomatic, and it is generally considered a benign condition 2, 3.
Clinical Manifestations and Complications
- Myocardial bridging can cause myocardial ischemia, leading to anginal symptoms, acute coronary syndrome, cardiac arrhythmias, and rarely, sudden cardiac death 2, 3, 5.
- The peak of clinical manifestation occurs during the third and fourth decades of life 3.
Diagnostic Methods
- Various non-invasive and invasive diagnostic methods can be used to evaluate the functional significance of bridging, including:
- Exercise echocardiogram can also be used to demonstrate severe apical ballooning and hypokinesis during peak exercise, with corresponding ST-segment elevation, resolving on rest 6.
Treatment Options
- Medical therapy, including beta-blockers, calcium channel blockers, and ivabradine, can be used to relieve symptoms and prevent adverse outcomes 3, 6.
- Invasive approaches, such as percutaneous coronary intervention, coronary artery bypass graft, and myotomy, can be performed in patients with symptoms refractory to maximally tolerated medical treatment 2, 3, 6.
- Surgical interventions, including deroofing the bridge and revascularisation of the affected region with bypass grafting, can also be considered 6.
Challenges in Management
- The lack of randomized clinical trials makes it difficult to determine the most effective management strategy for each patient 3, 6.
- There may be disagreement among experts on the optimal management of patients with myocardial bridging, highlighting the need for individualized treatment approaches 6.