Changes in common carotid artery intima-media thickness (IMT) are associated with stroke incidence in a multiethnic cohort, according to findings from the Multi-Ethnic Study of Atherosclerosis (MESA; NCT00005487) ancillary study for progression of IMT. Common carotid artery IMT is used as a predictive measure for cardiovascular events and stroke. However, studies that investigated the association between common carotid artery IMT and stroke have demonstrated mixed results [Lorenz et al. Stroke 2006; Hollander et al. Stroke 2002; O'Leary et al. N Engl J Med 1999; Chambless et al. Am J Epidemiol 2002]. Joseph F. Polak, MD, MPH, Tufts Medical Center, Boston, MA, presented findings from the MESA study.

The MESA study included 6814 individuals from 4 different ethnic groups (Caucasian-white, African-American, Chinese-American, and Hispanic-American) who were free of cardiovascular disease, without symptoms of atherosclerosis, and were capable of follow-up (median follow-up 3.0 years). The IMT progression substudy included 5640 participants. Ultrasonographies of the right common carotid artery were performed during two follow-up visits subsequent to the baseline visit. Ultrasonography studies included diameter curves, determined based on a 20-second-long series, and IMT measurements, determined from image selections at end-diastole.

The occurrence of stroke, defined as symptoms that lasted >24 hours or the detection of a clinically relevant lesion on brain imaging, was determined during the MESA follow-up visits or by phone interview, which was conducted every 9 to 12 months. Risk factors such as age, gender, systolic blood pressure, antihypertensive medications, cholesterol (high-density lipoprotein-HDL and low-density lipoprotein-LDL), diabetes, smoking, education, income, and ethnicity were also evaluated during this study, and Cox proportional hazards models were adjusted accordingly. Within this substudy, 39.5% of participants were Caucasian-white, 26.5% was African-American, 12.3% was Chinese-American, and 21.7% was Hispanic-American. The mean age was 64 years (range=46 to 88 years), and 52% was female.

This substudy revealed a mean rate of change in IMT of 0.015±0.05 mm, and 48 stroke events were observed. The rate of change in common carotid artery IMT was associated with stroke incidence in this multiethnic cohort (HR, 1.282; 1.014 to 1.620; p=0.0376). Age (p=0.0085), systolic blood pressure (p=0.0012), and HDL-cholesterol (p=0.0055) were associated with the highest risk after Cox proportional hazards models adjustment.

However, there was a stronger association prior to risk factor adjustments. The nonadjusted mean common carotid artery IMT was 0.71±0.19 mm for those with no stroke and 0.79±0.17 mm for stroke (p=0.0025), and the rate of change in common carotid artery IMT was 0.01±0.05 mm/year for those with no stroke and 0.04±0.07 mm/year for stroke (p=0.0506). The most significant risk factors that were associated with stroke, according to the nonadjusted data, were age (p=0.0007), systolic blood pressure (123.1±20.6 for no stroke and 138.8±22.7 for stroke; p<0.0001), treatment with hypertension medication (p=0.0020), and HDL-cholesterol (52.0±15.0 for no stroke and 46.5±11.2 for stroke; p=0.0028).

The results from the MESA study are promising with regard to the association between common carotid artery IMT and first-time stroke outcome. However, previous studies that investigated this association have yielded conflicting results. Therefore, additional studies are needed to support these findings.