Abstract 10405: Carotid Plaque, Not Intimal-Medial Thickness, Predicts Clinical Cardiovascular Disease: The Strong Heart Study
Background: Carotid ultrasound protocols used in epidemiologic studies vary in methodology based on location(s) of intimal-medial thickness (IMT--a potential marker of diffuse or “early” atherosclerosis) measurement, and whether focal thickening (atherosclerotic plaque) is separately categorized. We examined the prognostic utility of possible (IMT) and definite (plaque) atherosclerosis in predicting incident cardiovascular disease (CVD).
Methods: American Indians free of definite CVD were evaluated in Exam 3 of the Strong Heart Study with carotid ultrasound and CVD risk factor assessment. End-diastolic IMTs of the left and right common carotid arteries, areas largely free of focal atherosclerosis, were measured and averaged. Arterial mass was calculated from IMT and end-diastolic diameter as arterial cross-sectional area. Focal plaque was defined as discrete thickening >50% relative to the surrounding wall, most commonly involving the carotid bulb and/or internal carotid artery. The number of carotid segments containing plaque constituted the plaque score.
Results: 2462 subjects were followed for a mean of 5.6±1.7 years and experienced 361 CVD events (fatal and non-fatal stroke, CHF, myocardial infarction or definite coronary disease diagnosis). Time to event analyses were adjusted for age, gender, body mass index, hypertension, diabetes, cholesterol/HDL ratio, current smoking, fibrinogen and plasma creatinine. CVD events were predicted by the presence of focal plaque: HR=1.73, 95% CI:1.30–2.29, p<0.001; plaque score: HR=1.23 per segment affected, 95% CI:1.15-1.31, p<0.001; and arterial mass (HR=1.03, 95% CI:1.005–1.062, p=0.020) but not by IMT (HR=1.19, 95% CI:0.567–2.54, p=0.66).
Conclusions: Unequivocal evidence of atherosclerosis (plaque) and its extent (plaque score) are strong independent predictors of incident CVD events in individuals without pre-existing CVD, whereas IMT is not unless it is incorporated into a more global measure of vessel size. These findings support the utility of separate assessment of focal atherosclerosis and IMT in epidemiologic studies and in risk stratification protocols.
- © 2010 by American Heart Association, Inc.