Coronary steal

Overview

Coronary steal is a cardiovascular phenomenon in which blood flow is diverted—or "stolen"—away from a region of the heart muscle (myocardium) that is already deprived of adequate blood supply. It typically occurs when vasodilator medications or certain vascular conditions cause blood to preferentially flow through non-obstructed coronary vessels, leaving the already compromised regions even more deprived. This can lead to ischemia (insufficient oxygen delivery) and chest pain, particularly during stress or pharmacologic testing. Coronary steal is most often identified during cardiac stress testing with vasodilators such as adenosine or dipyridamole.

Causes

Coronary steal usually arises in the context of underlying coronary artery disease (CAD) or certain congenital or acquired vascular abnormalities. Common causes include:

• Coronary artery disease: Partial or severe narrowing of coronary vessels impairs perfusion and sets the stage for blood flow to be diverted away from affected regions

• Use of vasodilator drugs: Medications like adenosine, regadenoson, or dipyridamole during stress testing can cause coronary steal by dilating healthy vessels more than diseased ones

• Arteriovenous malformations or fistulas: Abnormal connections between arteries and veins can divert blood flow from myocardial tissue

• Coronary collateral vessels: In some cases, collaterals that form to bypass occlusions can contribute to the steal phenomenon

• Coronary artery bypass graft (CABG) complications: Steal can occur post-surgery due to competitive flow or anomalous graft behavior

Symptoms

Symptoms of coronary steal are related to myocardial ischemia and typically occur during periods of increased demand or vasodilation. They may include:

• Angina pectoris: Chest pain or pressure, especially during stress or medication-induced vasodilation

• Dyspnea: Shortness of breath

• Fatigue or exercise intolerance

• Palpitations

• Syncope or dizziness: In more severe cases

• Asymptomatic ischemia: In some cases, ECG or imaging changes may be present without obvious symptoms

Diagnosis

Coronary steal is typically identified during diagnostic evaluations for chest pain or suspected coronary artery disease. Common diagnostic tools include:

• Pharmacologic stress testing: Myocardial perfusion imaging using vasodilators such as adenosine or regadenoson can reveal areas of decreased perfusion due to steal

• Coronary angiography: Visualizes coronary anatomy and detects vessel narrowing or abnormal connections (e.g., fistulas)

• Cardiac MRI with stress perfusion: Can show regional perfusion defects associated with coronary steal

• Electrocardiogram (ECG): May show ischemic changes during stress testing

• Echocardiography: Stress echo may reveal wall motion abnormalities linked to ischemia

Treatment

Treatment of coronary steal focuses on correcting the underlying cause and restoring balanced myocardial perfusion. Depending on the clinical scenario, management may include:

• Optimizing coronary artery disease treatment: Using anti-anginal medications (e.g., beta-blockers, nitrates) and statins

• Avoidance of vasodilator stress agents: In patients prone to steal, alternative stress testing (e.g., dobutamine stress echo) may be used

• Revascularization: Percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) to improve blood flow to ischemic areas

• Treatment of arteriovenous malformations or fistulas: Surgical or catheter-based interventions may be required to eliminate abnormal blood flow patterns

• Lifestyle modification: Smoking cessation, diet changes, and exercise as part of broader cardiovascular risk reduction

Prognosis

The prognosis of coronary steal syndrome depends on the underlying cause and the extent of myocardial ischemia. If the condition is recognized early and managed appropriately, the risk of serious complications like myocardial infarction or heart failure can be significantly reduced. Persistent ischemia due to untreated coronary steal may lead to worsening symptoms and increased cardiovascular risk. With proper medical therapy and/or revascularization, most patients can achieve good symptom control and improved quality of life.