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NORMAL VALUES FOR COMMON CAROTID INTIMAL MEDIAL THICKNESS SHOULD BE ADJUSTED FOR AGE

NORMAL VALUES FOR COMMON CAROTID INTIMAL MEDIAL THICKNESS SHOULD BE ADJUSTED FOR AGE

Author Block MF Matangi, DW Armstrong, M Nault, D Brouillard, Kingston, Ontario

BACKGROUND: Maximal common carotid artery (CCA) intimal medial thickness (IMT) is now commonly used as a screening tool for detection of the presence of atherosclerosis. It is common practice to call a CCA IMT >1.0mm as being abnormal and >1.2mm as being high risk. There is general agreement that the presence of obvious plaque indicates high risk at any age. However when there is only CCA IMT thickening and no plaque then the normal values need to be adjusted for age, gender and perhaps even ethnicity.

METHODS and RESULTS: CAROTIDfile, the carotid duplex imaging module of CARDIOfile, our cardiology database was searched for patients age ≥40 years who had undergone carotid duplex imaging (CDI). Maximal CCA IMT was measured manually in the far wall. Patients were excluded if there was any degree of internal carotid artery stenosis by ICAVL imaging and velocity criteria. Of 2,210 CDI only 454 fulfilled the entry criteria. Patients were then separated into deciles of age beginning at age 40yrs, (viz: 40-49yrs, 50-59yrs, 60-69yrs, 70-79yrs and >80yrs). One way ANOVA was used to detect differences between means within the different decile age groups. A p value of <0.05 was considered significant
RESULTS: See Image below.
 

CONCLUSION: Maximal common carotid artery intimal medial thickness increases gradually with age in patients without obvious carotid disease in the form of plaque. When reporting intimal medial thickening for an individual, one should take into consideration the patient's age and the effect that age has on the normal values.