Carotid plaque, compared with carotid intima-media thickness, more accurately predicts coronary artery disease events: A meta-analysis
Introduction
Carotid intima-media thickness (CIMT), as measured by B-mode ultrasound of carotid arteries, is a simple and non-invasive imaging test assessing structural changes in the arterial wall and has been widely used as a surrogate marker of atherosclerotic disease. CIMT has been usually measured in the common carotid artery (CCA), rather than the carotid bulb (CB) or internal carotid artery (ICA), because CCA is easily visualized perpendicular to the ultrasound beam and provides more accurate, reproducible, and quantitative measurement [1]. However, the accuracy of CIMT as a marker of atherosclerosis has been questioned by the fact that main predictors of medial hypertrophy or intimal thickening of CCA are age and hypertension, which do not necessarily reflect the atherosclerotic process [2].
In contrast, carotid plaque has been shown to be more closely related to coronary artery disease (CAD) and to predict coronary events than CIMT [3], [4] S6, S10, S11. Carotid plaque predominantly occurs at sites of nonlaminar turbulent flow such as in the CB and the proximal ICA, but rarely in the CCA except in advanced atherosclerotic disease [5]. Thus, a thorough scan of all carotid arteries, including plaque assessment, may increase sensitivity for identifying subclinical vascular disease.
At present, there is no clear consensus on which CIMT assessment constitutes the best measurement of atherosclerosis assessment [1]. We hypothesized that the incorporation of plaque assessment into CIMT measurement significantly improves diagnostic values of carotid ultrasound. We conducted the present meta-analysis to compare the diagnostic accuracies of carotid plaque and CIMT for the prediction of CAD events.
Section snippets
Methods
Two reviewers (YI, JAC) independently searched Ovid MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews and conference proceedings from the American College of Cardiology and the American Heart Association through April 2011 using Medical Subject Headings (MeSH) and text words. The reference lists of the retrieved articles were also reviewed to identify for additional studies. There were no language restrictions. The exact search terms used
Results
The electronic database search identified 2064 citations. After title and abstract screening, we retrieved 167 articles for full paper evaluation, of which 11 population-based studies S1−S11 and 27 diagnostic cohort studies S12−S38 met our eligibility criteria (Supplement Fig. 1) (Supplement Reference). Baseline characteristics of included studies are shown in Supplement Table 2. Forrest plots of the sensitivity, specificity, positive LR, and negative LR are shown in Supplement Figs. 2–5.
The
Discussion
The present meta-analysis of population-based studies and diagnostic cohort studies showed that the ultrasound assessment of carotid plaque, compared with that of CIMT, had higher diagnostic accuracies for the prediction of future myocardial infarction and for the detection of CAD. The ultrasound screening for the presence of carotid plaque is simple, non-invasive imaging test and may be particularly useful in a general population given the higher negative predictive values. The absence of
Conclusion
In conclusion, the present meta-analysis of population-based studies and diagnostic cohort studies showed that the ultrasound assessment of carotid plaque, compared with that of CIMT, had higher diagnostic accuracies for the prediction of future myocardial infarction and for the detection of CAD. We therefore recommend that CIMT assessment should always be supplemented by a thorough scan of the extracranial carotid arteries for carotid plaque assessment to increase the diagnostic performance of
Acknowledgments
Funding sources: None.
Disclosures: None of the authors had a conflict of interest.
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