The prevalence of hypoechoic carotid plaques is greater in peripheral than in coronary artery disease and is related to the neutrophil count.

OBJECTIVE: Previous reports indicate that the prevalence and severity of carotid stenoses is greater in peripheral artery disease (PAD) than in coronary artery disease (CAD). To date, no study has compared these two populations with respect to plaque echogenicity, which is an independent risk factor for cerebrovascular events.

METHODS: In 43 PAD patients without CAD and in 43 CAD patients without PAD, carotid plaques were studied with high-resolution B-mode ultrasound and by computerized measurement of the gray-scale median.

RESULTS: At visual analysis, the prevalence of hypoechoic plaques was 39.5% in PAD and 18.6% in CAD (P = .033). The corresponding values for gray-scale median analysis were 34.9% and 14.0% (P = .024). At multivariate analysis, PAD patients showed a greater risk of having hypoechoic plaques than CAD patients at visual (odds ratio [OR], 4.39, 95% confidence interval [CI] 1.21-15.92, P = .025) and gray-scale median analysis (OR, 5.13; 95% CI, 1.27-20.67; P = .021). This association was no longer significant when neutrophil number was included among the covariates. In this model, only an increased neutrophil count was associated with hypoechoic plaques (P < .01 for both visual and gray-scale median analysis). Indeed, neutrophil count was greater in PAD than in CAD (4.4 +/- 1.0 vs 3.9 +/- 1.2 10(9)/L, P = .030). The concordance between visual typing of carotid plaques and gray-scale median measurement was good (rho = 0.714, P < .01).

CONCLUSIONS: Compared with CAD patients, those with PAD, in addition to a greater atherosclerotic burden, may have characteristics of instability of carotid plaques that, in turn, may result in cerebrovascular events. Prospective studies are needed to assess specifically whether the greater prevalence of hypoechoic plaques in PAD vs CAD patients is associated with a greater risk of cerebrovascular events.