Case Presentation: A 70 year old Caucasian male with coronary artery disease status post 3 vessel coronary artery bypass graft (CABG) (including a left internal mammary artery (LIMA) graft to left anterior descending (LAD) coronary artery), porcelain aorta, hypertension, heart failure with recovered ejection fraction, peripheral artery disease, and obstructive sleep apnea presented to a cardiology clinic follow-up with an 8-month history of progressive symptomatic hypotension with dizziness. His blood pressure was 69/41 on presentation, and he was transported to the emergency room, where he did not improve with 500 mL fluid bolus. The patient was admitted to the medical ICU and norepinephrine was started. Transthoracic echocardiogram showed a reduced ejection fraction of 20-25%, leading to subsequent left heart catheterization showing patent bypass grafts. However, the patient demonstrated a 50 mmHg pressure gradient between central aortic and noninvasive pressure measurement of his left upper extremity. CT angiogram showed atherosclerotic plaque at the origin of the great vessels with moderate stenosis at the origin of the left subclavian artery. Given the drop in ejection fraction and his history of LIMA-LAD bypass graft, there was concern for coronary subclavian steal syndrome, leading vascular surgery to place a stent to treat the left subclavian stenosis. After the procedure his left radial pulse was bounding and his dizziness resolved on his post-discharge follow-up.
Discussion: Subclavian steal phenomenon occurs when there is stenosis within the subclavian artery proximal to the origin of the vertebral artery causing a drop in pressure distal to the stenosis leading to retrograde blood flow from the vertebral artery into the subclavian. When these anatomical abnormalities cause symptoms of cerebral ischemia, it is termed subclavian steal syndrome (SSS). However, steal syndromes can occur in other vascular territories as well, including coronary subclavian steal syndrome (CSSS), where retrograde flow occurs through a LIMA-LAD graft in a patient who previously has undergone coronary artery bypass graft surgery.1,2 Our case presents an example of simultaneous vertebral and coronary subclavian steal syndrome, where proximal subclavian stenosis causes retrograde blood flow from the LIMA to the distal subclavian artery, causing myocardial ischemia and reduced ejection fraction, in addition to retrograde blood flow through the vertebral artery resulting in vertebrobasilar insufficiency and recurrent syncope. 2 The most common etiology of subclavian steal is atherosclerosis. However, rarer causes include autoimmune diseases (ie Takyasu’s arteritis), congenital vascular abnormalities, and head or neck radiation. 3–6 Diagnosis includes imaging (carotid artery duplex, MRI, CTA) in addition to clinical symptoms suggesting steal. Stent placement or surgical bypass can increase blood flow to the patient’s distal subclavian and restore antegrade flow to the vertebral artery and LIMA graft.
Conclusions: Our case of SSS and CSSS highlights how a proper understanding of a patient’s specific anatomy can aid in building an individualized differential and treatment plan. It is important to consider SSS or CSSS in the differential for vertebrobasilar symptoms like dizziness and syncope or for heart failure with newly reduced ejection fraction, especially in the setting of significant vascular disease.