A negative carotid plaque area test is superior to other noninvasive atherosclerosis studies for reducing the likelihood of having underlying significant coronary artery disease

Abstract

Objective: Coronary calcium score (CCS), carotid plaque area (CPA), intima-media thickness (IMT), and C-reactive protein (CRP) are independent predictors of cardiovascular prognosis. Although each test may enhance risk stratification, their comparative abilities to screen for underlying coronary stenoses in individual patients is less established.

Methods and results: Forty-two patients who had a 16-slice coronary computed tomography angiogram (CTA) performed were invited to have CPA, IMT, and CRP measured. CPA was defined as the sum of all the cross-sectional areas of each plaque >1 mm in diameter found in all carotid vessels bilaterally. CCS and the number plus degree of stenotic coronary arteries were determined by CTA. The presence of clinically significant coronary artery disease (CAD) was defined as the existence of any stenosis > or =50%. CTA identified clinically significant CAD in 43% of the patients. CPA >0 was more sensitive (72%) and specific (58%) than a CCS >0 (58% and 55%) for identifying CAD. A "clean" carotid artery (CPA=0) provides a superior negative predictive value (74%) and likelihood ratio of a negative test (0.48) than all other studies, in particular versus a CCS=0 (65% and 0.72). The areas under the receiver-operator curves for CPA and CCS in relation to any CAD were similar (0.640 versus 0.675). Carotid IMT and CRP performed poorly compared with CPA and CCS. For detecting CAD in only the left main or left anterior descending artery, the negative predictive value and likelihood ratio of a negative test remained superior for CPA (87% and 0.33) compared with CCS (80% and 0.56). In our population with a prevalence of these coronary lesions of 30%, the post-test probability in any patient with a negative CPA result is reduced to 10%.

Conclusions: CPA determination is superior to CCS, IMT, and CRP in its ability to reduce the likelihood of clinically significant underlying CAD in patients of varying cardiac risk.