Laboratory Studies
Laboratory studies to be considered in the workup for cholesterol embolism include the following:
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Complete blood count (CBC) - Leukocytosis with left shift is nonspecific; eosinophilia strongly suggests atheroembolization and is present in as many as 80% of patients with cholesterol embolism syndrome
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Chemistry - Elevated blood urea nitrogen (BUN) and creatinine levels are present in virtually all cases of cholesterol embolism syndrome (CES)
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Urinalysis - Microscopic hematuria, proteinuria, and hyaline casts are common; pyuria actually may be eosinophiluria, a major clue for the diagnosis of CES
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Tissue-specific laboratory tests - Muscle injury causes an elevated creatine kinase (CK) level; myocardial, pancreatic, and hepatobiliary involvement produces increases in cardiac enzymes, amylase, and hepatobiliary enzymes
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Inflammatory mediators - Nonspecific findings include hypocomplementemia, positive rheumatoid factor (RF), antinuclear antibodies (ANAs), and elevated C-reactive protein [7] (CRP) and erythrocyte sedimentation rate (ESR); one study found a CRP level higher than 1.0 mg/dL to be an independent predictor of cholesterol emboli in patients with coronary artery disease (CAD)
Imaging Studies
Angiography
Contrast angiography of involved organs may be performed to rule out more treatable causes of tissue ischemia, such as polyarteritis nodosa. Angiography may induce atheroembolism.
Echocardiography
Transesophageal echocardiography (TEE) is an increasingly well accepted imaging tool for detecting atheromatous lesions in the ascending and thoracic aorta. [8, 9, 10, 11] Protruding mobile atheromatous masses have been associated with a higher incidence of stroke or cholesterol embolism in patients who undergo cardiac bypass or patients who receive anticoagulants. TEE may eventually be performed in all patients undergoing bypass before aortic cannulation. It also may be performed in all patients with ischemic stroke with an unclear etiology.
Computed tomography
Thin sections viewed on nonenhanced dual helical (spiral) computed tomography (CT) may be useful for rapid and noninvasive detection of protruding aortic atheroma. [12] This test can help visualize areas that are poorly imaged on TEE, such as the distal ascending aorta and arch. One study suggests 87% sensitivity, 82% specificity, and 84% overall accuracy.
Magnetic resonance imaging
Data on magnetic resonance imaging (MRI) and atheromatous plaque are relatively sparse, but a reasonable expectation is that MRI should exhibit good sensitivity in this setting.
Procedures
Demonstration of cholesterol crystals in occluded arterioles is the only definitive test for cholesterol embolism. Skin, [13] renal, muscle, or gastrointestinal (GI) tract biopsy may reveal crystal ghosts inside vessels. Often, multiple samples may be necessary to demonstrate the crystals.
Histologic Findings
The actual cholesterol crystals are dissolved during fixation, leaving intra-arterial biconvex ghosts. Often, the crystals are missed because the depth of the tissue sample is inadequate. If these ghosts are absent, the diagnosis still may be inferred from the presence of fibrinoid necrosis (see the image below) and a foreign-body reaction in tissues commonly involved by atheromatous emboli in a patient with consistent clinical findings. Exuberant adventitial fibrosis contributes to vessel lumen occlusion.
Necrosis of the abdominal wall in a patient with cholesterol embolism syndrome who received anticoagulation.
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Cholesterol crystal embolization from upstream coronary artery plaque after percutaneous transluminal coronary angioplasty.
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Necrosis of the abdominal wall in a patient with cholesterol embolism syndrome who received anticoagulation.
