Is an absent left circumflex coronary artery (LCx) a concern?

From the Guidelines

An absent left circumflex coronary artery (LCx) is a concern due to its potential association with increased risk of myocardial ischemia, ventricular dysfunction, and sudden cardiac death, particularly in the presence of high-risk anatomic features or symptoms. This condition is a type of coronary artery anomaly, which occurs in approximately 1% to 1.3% of patients undergoing coronary angiography 1. The level of concern depends on various factors, including the presence of symptoms, the anatomy of the coronary arteries, and the patient's overall cardiac function.

When evaluating an absent LCx, it is essential to consider the following key points:

• The presence of symptoms such as chest pain, shortness of breath, or syncope, which may indicate myocardial ischemia or ventricular arrhythmia
• The anatomy of the coronary arteries, including the presence of high-risk features such as a slit-like coronary ostium, an acutely oblique proximal coronary course, or a longer segment running within the arterial wall (“intramural”) 1
• The patient's overall cardiac function, including the presence of ventricular dysfunction or arrhythmias
• The results of cardiac imaging studies, such as coronary CT angiography or cardiac MRI, which can help assess coronary anatomy and blood flow patterns

Management of an absent LCx typically involves a comprehensive cardiac evaluation, including:

• Cardiac imaging studies to fully assess coronary anatomy and blood flow patterns
• Stress testing to determine if there are any functional limitations
• Lifestyle modifications, such as avoiding strenuous exercise or managing stress
• Medications, such as beta-blockers or calcium channel blockers, to reduce cardiac workload
• Surgical intervention, in some cases, to improve blood flow or repair any underlying anomalies 1.

From the Research

Clinical Presentation and Diagnosis

• The absence of the left circumflex coronary artery (LCx) can present with symptoms such as exertional chest pain or angina, as seen in cases reported by 2 and 3.
• Diagnosis is typically made through coronary angiography, which can reveal the absence of the LCx and a superdominant right coronary artery, as noted in studies 4, 5, and 6.
• Additional diagnostic tests, such as electrocardiograms, exercise stress tests, and thallium-201 myocardial perfusion studies, may also be used to evaluate patients with suspected LCx absence, as described in 2.

Prevalence and Associated Conditions

• The prevalence of congenital coronary artery anomalies, including LCx absence, is estimated to be around 1% in the general population, with LCx absence being a rare condition affecting approximately 0.003% of the population, as reported in 3 and 6.
• Associated conditions, such as coronary artery disease, may be present in some cases, as noted in 5, which found that 45.5% of cases had associated coronary artery disease.

Management and Prognosis

• Management of LCx absence typically involves a comprehensive anatomical and functional assessment to determine the best course of treatment, as emphasized in 5 and 6.
• In some cases, patients with LCx absence may remain stable and asymptomatic, while others may require intervention, such as coronary artery bypass grafting, as described in 4.
• The prognosis for patients with LCx absence is generally good, although it depends on the presence of associated conditions and the effectiveness of treatment, as noted in 2 and 3.