Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (75 page)

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Authors: Mary A. Williamson Mt(ascp) Phd,L. Michael Snyder Md

BOOK: Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis

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Adjunctive risk assessment tools such as C-reactive protein, other circulating inflammatory biomarkers, and subclinical atherosclerosis imaging (CT, carotid intimal thickness or CIMT) have emerged within the past decade and have been cautiously included in recommendations for risk assessment in asymptomatic adults (level of evidence B: no randomized trials based on management).

CRP (along with CT scanning and CIMT) is currently recommended (Class IIa) for asymptomatic moderate-risk individuals in whom lipid lowering therapy is considered based on atherosclerotic risk alone (i.e., LDL-C < 130 mg/dL not on medication).

Individuals with evidence of peripheral arterial disease, symptomatic carotid disease, asymptomatic carotid disease >50%, diabetes mellitus, and/or abdominal aortic aneurysm are considered to have a coronary heart disease risk equivalent and warrant aggressive preventive therapy akin to established coronary atherosclerosis. In these patients, subsequent lipid assessment is required for titration of therapy. Adjunctive testing for the diagnosis of coronary atherosclerosis (CRP/imaging) is not justified.

Laboratory Findings

Core laboratory: Lp(a) and homocysteine are increased.

Elevated CRP (if first result is >3.0 mg/L, repeating the test at least 2 weeks later when patient is in metabolically stable state free of infection or acute illness is recommended). Persistent values >3.0 mg/L define a high-risk category. The Reynolds Risk Score incorporates CRP into initial risk assessment (
http://www.reynoldsriskscore.org
). Overall the modest strength of CRP inclusion into risk assessment points argues against a causative role in atherosclerosis.

Coronary artery calcium scores exceeding 100 AU (Agatston units) or 75th percentile are considered high risk for coronary events, as are any carotid plaque or IMT exceeding 75th percentile.

Suggested Readings

Faxon DP, Fuster V, Libby P, et al. Atherosclerotic vascular disease conference: writing group III: pathophysiology.
Circulation.
2004;109:2617–2625.

Greenland P, Alpert JS, Beller GA, et al. 2010 ACCF/AHA guidelines for assessment of cardiovascular risk in asymptomatic adults: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines.
J Am Coll Cardiol.
2010;56:e50–e103.