Cholesterol Embolization Syndrome

Cholesterol embolization syndrome (atheroembolism) results from showers of cholesterol crystals and plaque debris released from ulcerated atherosclerotic plaques, mainly in the aorta and its major branches. The crystals lodge in small arteries and arterioles of 100 to 200 micrometres, producing multi-organ ischaemia and an intense inflammatory response.

Epidemiology

• Autopsy prevalence is under 5% in the general population and up to 25% in patients with severe aortic atherosclerosis or after aortic surgery.
• The typical patient is male, aged over 60, with hypertension, smoking history, diabetes, chronic kidney disease, aortic aneurysm or severe aortic atheroma.
• Protruding or mobile aortic plaques above 4 mm on transoesophageal echocardiography carry the highest risk.

Precipitating events

• Arterial instrumentation: coronary or peripheral angiography, angioplasty and stenting, intra-aortic balloon pump, cardiac and aortic surgery, endovascular aneurysm repair.
• Anticoagulation and thrombolysis: warfarin, heparin and fibrinolytic agents are thought to disrupt the plaque's protective thrombus.
• Spontaneous: occurs in a minority, probably triggered by plaque rupture.

Pathophysiology

• Cholesterol crystals obstruct vessels mechanically, then provoke a foreign body reaction with neutrophils, eosinophils and giant cells, followed by intimal proliferation and fibrosis. The vessel becomes permanently occluded, so damage continues to evolve over weeks.
• Showers can recur over weeks to months, explaining the stepwise course.

Organs most affected

• Kidneys (most common systemic site), skin and lower limbs, gastrointestinal tract, central nervous system, eyes, pancreas and muscle.

Prognosis is poor. In-hospital mortality ranges from 10 to 40% and 1-year mortality can reach 60 to 80% in series with multi-organ involvement. Renal involvement leads to dialysis in 28 to 61%, though some recover renal function after weeks to months.

Onset is typically days to weeks after a precipitant, and sometimes delayed by up to 2 months, especially after anticoagulation.

Skin and extremities (35 to 90%)

• Livedo reticularis, usually affecting the lower limbs, buttocks and abdomen.
• Blue toe syndrome: painful cyanotic, mottled toes with palpable pedal pulses, a key discriminator from large vessel occlusion.
• Purpura, petechiae, nodules, ulcers and dry gangrene, with intense pain.

Renal

• Subacute or stepwise rise in creatinine over weeks, and sometimes oliguria.
• New or worsened hypertension, mild proteinuria, and bland urinary sediment. This differs from contrast nephropathy, which peaks at 3 to 5 days and recovers within 7 to 10 days.

Gastrointestinal

• Abdominal pain, nausea, gastrointestinal bleeding, bowel ischaemia or infarction, pancreatitis, cholecystitis, and hepatic dysfunction.

Neurological and ocular

• Amaurosis fugax, retinal Hollenhorst plaques, TIA, stroke, confusion, spinal cord infarction.

Systemic

• Fever, weight loss, myalgia and malaise, which mimic systemic vasculitis or endocarditis.

Differential diagnosis

• Polyarteritis nodosa, ANCA-associated vasculitis and cryoglobulinaemic vasculitis.
• Infective endocarditis with septic emboli, thromboembolic occlusion (absent pulses), and antiphospholipid syndrome.
• Contrast nephropathy, thrombotic microangiopathy and calciphylaxis.
• Acute renal artery occlusion, and acute interstitial nephritis (eosinophilia and eosinophiluria also occur).

Diagnosis combines the clinical context (recent instrumentation, anticoagulation or known aortic disease) with supportive findings and, where feasible, histology.

Laboratory findings

• Eosinophilia in about 60 to 80% at some stage, usually transient and peaking at 2 to 4 weeks.
• Raised ESR and CRP, leukocytosis, anaemia, thrombocytopenia, and low complement (C3, C4) in a subset.
• Raised creatinine, urea, LDH, CK, amylase and liver enzymes depending on organ involvement.
• Urinalysis with mild proteinuria, microscopic haematuria and eosinophiluria (Hansel stain, with low sensitivity).
• Negative ANCA, anti-GBM and cultures. Check cryoglobulins, antiphospholipid antibodies and serology to exclude mimics.

Histology is confirmatory

• Biopsy of an affected site, ideally an involved skin lesion (deep punch or elliptical biopsy including subcutis, with multiple levels), or kidney or muscle.
• Findings are biconvex, needle-shaped clefts in arteriolar lumens (crystals dissolved during processing), a foreign body giant cell reaction, and intimal fibrosis.
• Renal biopsy is reserved for diagnostic uncertainty. The yield is lower because of patchy involvement.

Imaging and source identification

• Fundoscopy for Hollenhorst plaques.
• CT angiography or MR angiography of the aorta and branches, and transoesophageal echocardiography for aortic arch atheroma.
• Renal ultrasound shows normal or small kidneys without obstruction.
• Duplex or angiography of the limb arteries to confirm patent large vessels.

Gastrointestinal involvement requires CT of the abdomen, and endoscopy with biopsy of ulcers when bleeding.

No treatment is proven to dissolve crystals or reverse established ischaemia. Care focuses on removing the trigger, preventing further embolisation, and supporting failing organs.

Removing precipitants

• Stop warfarin, heparin and thrombolytics unless a compelling indication exists (mechanical heart valve, recent stent, high-risk atrial fibrillation or venous thromboembolism). Where anticoagulation is essential, use the lowest effective intensity and review frequently.
• Avoid further arterial catheterisation and aortic manipulation. If vascular access is required, use minimal manipulation, careful technique and embolic protection where available.

Plaque stabilisation and risk reduction

• Atorvastatin 40 to 80 mg daily or rosuvastatin 20 to 40 mg daily, targeting LDL cholesterol below 55 mg/dL (1.4 mmol/L). Observational studies link statin therapy with improved survival and renal outcomes.
• Aspirin 75 to 100 mg daily.
• Blood pressure control with an ACE inhibitor or angiotensin receptor blocker, started cautiously with monitoring of creatinine and potassium, while avoiding hypotension that worsens renal perfusion.
• Smoking cessation, glycaemic control and weight management.

Anti-inflammatory therapy

• Corticosteroids have limited evidence. They are considered in patients with progressive renal failure or marked eosinophilic and inflammatory features: prednisolone 0.5 to 1 mg/kg daily (typically 40 to 60 mg) for 1 to 4 weeks, tapered over several weeks after clinical response.
• Weigh the risk of infection and wound healing problems. Steroids do not reverse ischaemic necrosis.

Organ-specific and supportive care

• Kidney: avoid nephrotoxins (NSAIDs, contrast), maintain euvolaemia, manage hyperkalaemia and acidosis, and start dialysis for standard indications. A trial of dialysis is warranted because recovery occurs in a proportion of patients over weeks to months.
• Skin and limbs: pain control with gabapentin 300 mg at night titrated to 1800 mg/day, and opioids as needed. Local wound care with conservative management of dry gangrene, allowing demarcation before amputation. Revascularisation is generally unhelpful for small vessel disease.
• Iloprost infusion (0.5 to 2 nanograms/kg/min) or LDL apheresis have been reported in refractory ischaemic digits, with limited supporting data.
• Gastrointestinal: bowel rest, nutrition support, proton pump inhibitor (pantoprazole 40 mg daily) and surgery for infarction or perforation.
• Nutrition, glucose control and secondary prevention of cardiovascular disease.

Source control

• Symptomatic, large or mobile atheroma in the aorta or an aneurysm may be treated with endovascular stent graft exclusion, surgical endarterectomy or bypass. Weigh the risk of procedural showering against ongoing embolisation.
• Embolic protection devices for carotid and renal stenting.

Prevention in high-risk patients

• Before angiography or aortic surgery in patients with known severe aortic atherosclerosis, consider non-invasive imaging, a radial approach, minimal catheter manipulation, and pre-procedural statin therapy.
• Review the need for anticoagulation and thrombolysis in patients with recognised aortic atheroma.

Follow-up

• Monitor creatinine, eosinophil count and CRP weekly for the first 4 to 6 weeks, then monthly. Watch for new organ involvement and recurrence.
• Long-term cardiovascular risk management and vascular surgery review.