Causes of Coronary Artery Aneurysm in Adults
In adults, atherosclerosis is the predominant cause of coronary artery aneurysms, accounting for the vast majority of cases, while Kawasaki disease represents the most common etiology in younger adults who had the disease in childhood. 1, 2, 3
Primary Etiologies
Atherosclerotic Disease (Most Common in Adults)
Atherosclerosis causes coronary artery aneurysms through a process of "positive remodeling" where the vessel wall dilates abnormally. This is the leading cause in the adult population and is frequently discovered incidentally during coronary imaging. 2, 3, 4
Kawasaki Disease (Leading Cause in Young Adults)
The vast majority of acquired coronary aneurysms in children and younger adults are due to Kawasaki disease, a generalized vasculitis of unknown etiology that typically occurs in children under 5 years old. 5 Late sequelae include coronary artery aneurysm, stenosis, thrombosis, or fistula formation that persist into adulthood. 6 These patients require lifelong follow-up with quantitative assessment of luminal dimensions. 6
- Giant aneurysms (≥8 mm or Z score ≥10) carry particularly high risk for thrombosis due to abnormal flow conditions with low wall shear stress and stasis 7
- Stenoses often develop over time at the proximal or distal ends of aneurysms, creating additional thrombotic risk 1
Secondary Etiologies
Inflammatory/Autoimmune Conditions
- Takayasu arteritis: Inflammatory lesions develop inside the aortic and coronary vessel walls with inflammatory infiltrate, smooth muscle and fibroblast necrosis, and fibrosis 8, 9
- Systemic autoimmune diseases: Associated with chronic inflammatory disease states 6
- Behçet's disease: Can affect coronary arteries 8
Infectious Causes
- Syphilitic aortitis: Can extend to involve coronary arteries, though primarily affects the ascending aorta 8
- Suppurative bacterial or fungal aortitis: Rare but can cause focal destruction with aneurysm formation 8
Congenital/Structural
Iatrogenic
- Post-percutaneous coronary intervention: Recognized complication of coronary interventions 9
- Post-cardiac surgery: Can occur after aortic valve replacement or other cardiac procedures 8
Toxic/Drug-Related
- Cocaine and amphetamine use: Associated with coronary aneurysm formation and dissection 8
Clinical Pitfalls
Do not assume all coronary aneurysms in adults are atherosclerotic. In young adults presenting with acute coronary syndrome and unanticipated aneurysmal changes, maintain high suspicion for prior Kawasaki disease, particularly when the initial diagnosis was missed in childhood or not followed up after transition to adult care. 7
The presence of chronic inflammatory disease states (HIV, viral hepatitis, systemic autoimmune disease) should prompt consideration of non-atherosclerotic etiologies, as these are associated with overall poor cardiovascular outcomes. 6
Giant coronary aneurysms (>2 cm, >5 cm, or >4 times normal vessel size) require immediate risk stratification regardless of etiology, as they carry substantially higher risk for thrombosis, rupture, and sudden cardiac death. 9, 4
Diagnostic Approach
Multimodality imaging is essential for characterization:
- Invasive coronary angiography remains gold standard but should be supplemented with intravascular ultrasound (IVUS) to demonstrate true luminal dimensions 7, 10
- Coronary CT angiography provides high-resolution anatomic detail and can identify calcification patterns 7, 2
- Cardiovascular magnetic resonance angiography offers radiation-free alternative 2
In young adults without traditional cardiovascular risk factors presenting with coronary aneurysms, specifically evaluate for Kawasaki disease history, recreational drug use (cocaine, amphetamines), inflammatory conditions, and connective tissue disorders before attributing the aneurysm to atherosclerosis. 6, 2