Coronary Artery Ectasia

Diffuse or segmental dilatation of a coronary artery to 1.5 times or more the diameter of an adjacent normal segment. A localised dilatation of the same degree is an aneurysm; a giant aneurysm exceeds 8 mm (or 4 times the normal diameter).

• Found in about 1.5 to 5% of coronary angiograms (up to about 10% in some regions), male to female about 3 to 4:1. The right coronary artery is most often affected (about 70%), then the left anterior descending and circumflex arteries; the left main artery is involved in less than 0.1%.
• Causes: atherosclerosis (about half), congenital (about 20 to 30%), vasculitis and connective tissue disease (Kawasaki disease, Takayasu arteritis, polyarteritis nodosa, lupus, Ehlers-Danlos and Marfan syndromes), infection (syphilis, mycotic embolus), iatrogenic injury (atherectomy, drug eluting stents, balloon angioplasty), and cocaine. It is associated with abdominal aortic aneurysm.
• Mechanism: medial degradation by matrix metalloproteinases, with disordered nitric oxide handling and inflammation. Slow, turbulent flow in the dilated segment promotes thrombus, embolisation, vasospasm and microvascular dysfunction, so ischaemia occurs without obstruction.
• Annual risk of infarction or death is about 1 to 2%.

• Often asymptomatic and found incidentally. Typical or atypical angina, acute coronary syndrome (often from thrombus in the dilated segment), and occasionally sudden death. Examination is normal.
• Differential diagnosis: atherosclerotic coronary disease with positive remodelling, Kawasaki aneurysm, coronary vasospasm, spontaneous coronary artery dissection, coronary artery fistula, and post-stent aneurysm.
• Complications: thrombosis and infarction, distal embolism, aneurysm rupture with tamponade, fistula formation, compression of adjacent structures, and stent malapposition with late stent thrombosis after percutaneous intervention.

• Coronary angiography shows dilatation with slow, sluggish flow and contrast stasis in the segment. Classify by extent: diffuse disease in two or three vessels (type I), diffuse in one vessel and localised in another (type II), diffuse in one vessel only (type III), localised or segmental (type IV).
• CT coronary angiography gives diameter, wall calcification and thrombus. Intravascular ultrasound or optical coherence tomography shows wall structure and vessel size.
• Stress testing may show ischaemia in the absence of obstruction.
• Blood tests: lipids, HbA1c, CRP, ESR, antinuclear antibody and antineutrophil cytoplasmic antibodies if vasculitis is suspected, syphilis serology, and history of Kawasaki disease or cocaine use.
• Echocardiography for the aortic root and left ventricular function; ultrasound of the abdominal aorta in men over 60 and in anyone with a proven aneurysm at another site.

• Evidence for specific therapy is limited, and treatment follows the cause and the complications.
• Risk factor control:
  • Atorvastatin 40 to 80 mg daily (LDL cholesterol target less than 1.4 mmol/L when atherosclerosis is present); blood pressure target less than 130/80 mmHg; smoking cessation; glycaemic control.
• Antithrombotic therapy:
  • Aspirin 75 to 100 mg daily for most patients.
  • Anticoagulation for a giant aneurysm, documented thrombus, or recurrent thrombotic events: warfarin to INR 2.0 to 3.0 (or apixaban 5 mg twice daily, 2.5 mg twice daily if two of age 80 or more, weight 60 kg or less, creatinine 133 micromol/L or more), often combined with aspirin 75 to 100 mg daily; weigh bleeding risk carefully.
  • Kawasaki aneurysm with giant dimension: aspirin 3 to 5 mg/kg/day plus warfarin to INR 2.0 to 3.0 (or low molecular weight heparin) in children.
• Anti-anginal therapy:
  • Bisoprolol 2.5 to 10 mg daily; amlodipine 5 to 10 mg daily or diltiazem modified release 90 to 360 mg daily where vasospasm contributes.
  • Nitrates may worsen slow flow in ectatic segments; use with caution (evidence is limited).
• Acute coronary syndrome in ectasia:
  • Aspirin 300 mg load then 75 to 100 mg daily; ticagrelor 180 mg then 90 mg twice daily or clopidogrel 300 to 600 mg then 75 mg daily; heparin (unfractionated heparin 60 units/kg bolus, maximum 4000 units, then 12 units/kg/h).
  • Angiography with thrombus aspiration or stenting where a culprit stenosis exists. Drug eluting stents in ectatic segments risk malapposition and late thrombosis, so size by intravascular imaging; covered stents can seal a localised aneurysm.
• Surgery:
  • Aneurysm resection or ligation with bypass grafting for a large aneurysm (greater than 20 mm, or greater than 3 to 4 times the normal diameter), left main involvement, rupture, compression, or recurrent thrombosis despite medical therapy.
• Treat the cause: immunosuppression for active vasculitis (prednisolone 0.5 to 1 mg/kg/day with specialist input), penicillin for syphilis (benzathine benzylpenicillin 2.4 million units IM weekly for 3 doses in late disease).
• Special groups:
  • Children: Kawasaki follow up with serial echocardiographic measurement of coronary z-scores and anticoagulation for large lesions.
  • Pregnancy: low dose aspirin 75 to 100 mg is acceptable; avoid warfarin in the first trimester and use enoxaparin 1 mg/kg SC twice daily when anticoagulation is needed.
  • Renal impairment: adjust enoxaparin and avoid iodinated contrast where possible.
• Red flags: ischaemic chest pain with ST change, syncope, hypotension and tamponade (rupture), embolic event.
• Follow up: yearly clinical review; CT coronary angiography every 1 to 2 years for large or growing aneurysms; repeat imaging for any change in symptoms.