Elsevier

Atherosclerosis

Volume 195, Issue 1, November 2007, Pages e197-e201
Atherosclerosis

Presence of calcified carotid plaque predicts vascular events: The Northern Manhattan Study

https://doi.org/10.1016/j.atherosclerosis.2007.03.044Get rights and content

Abstract

Objective

The prognostic implications of carotid plaque calcification (CPC) relative to subsequent vascular events are unclear. Our aim was to determine the association between CPC and risk of vascular events in a prospective multi-ethnic cohort.

Methods

CPC was assessed among 1118 stroke-free subjects (mean age 68 ± 8 years; 59% women; 59% Hispanic, 22% black, 19% white) from the Northern Manhattan Study using high-resolution B-mode ultrasound. CPC was defined by presence of any acoustic shadowing associated with carotid plaque, producing a reduction in echo amplitude due to intervening structures with high attenuation. Using Cox proportional hazards models, hazard ratios (HR) were estimated for the combined vascular outcome, defined as ischemic stroke (IS), myocardial infarction (MI) or vascular death (VD).

Results

Carotid plaque was present in 637 (57%) subjects. CPC was present in 225 subjects (20% of total cohort; 35% of those with plaque). During a mean follow-up time of 2.7 years, the combined vascular outcome occurred among 52 subjects (20 IS, 22 MI, and 24 VD). Adjusting for demographics, major vascular risk factors, and carotid intima media thickness, those with CPC (in comparison to those without plaque) had a significantly increased risk of the combined vascular outcome (HR 2.5, 95% CI 1.0–5.8).

Conclusions

In this population-based cohort, the presence of calcified carotid plaque, as assessed by high-resolution B-mode ultrasound, was an independent predictor of vascular events. It may serve as a simple and non-invasive marker of increased atherosclerotic risk and further aid in vascular risk stratification.

Introduction

The association between cardiovascular disease and vascular calcium deposition has been known since the 19th century. More recent studies have confirmed that coronary artery calcification, as detected by electron beam computed tomography (EBCT), is a marker of CAD severity and a predictor of coronary events [1], [2], [3], [4] and stroke [5]. However, studies assessing the association between carotid plaque calcification (CPC) and vascular events have produced more conflicting results [6], [7], [8], [9]. Hence, we undertook this study to prospectively determine the association between CPC, as assessed by ultrasonography, and the incidence of vascular events in a multi-ethnic stroke-free cohort. We hypothesized that presence of CPC increases the risk of vascular events.

Section snippets

Subjects and baseline evaluation

As previously described [10], the Northern Manhattan Study (NOMAS) is an ongoing prospective cohort study of stroke risk factors and outcomes. Between 1993 and 1997, 3298 subjects were enrolled who were stroke-free, >40 years of age, and residing in northern Manhattan. A carotid plaque calcification and intima-media thickness (IMT) sub-study of NOMAS began in 2000. Ultrasound data with at least one annual follow-up visit were available for 1118 NOMAS subjects.

Baseline data collection was

Results

Among 1118 subjects (mean age 68 ± 8 years; 59% women; 59% Hispanic, 22% black, 19% white), 481 (43.0%) had no plaque, 412 (36.9%) had only non-calcified plaque, and 225 (20.1%) had calcified plaque. Baseline characteristics of the cohort are shown in Table 1. Those who had calcified plaque were older, more frequently white, more likely to have completed high school, more commonly had concurrent vascular risk factors such as diabetes, hypercholesterolemia, and cardiac disease. Mean IMT was higher

Comment

We found that the presence of calcified carotid plaque was a strong and independent predictor of the combined vascular events. The association was independent of traditional cardiovascular risk factors. The effect was also independent of carotid IMT, an established strong predictor of vascular events [18]. Our results are consistent with some prior studies and support the hypothesis that arterial calcification signifies in situ plaque vulnerability and serves as a marker for generalized

Disclosures

The authors have no conflicts of interest to disclose. Each author had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Acknowledgements

Funding sources: The study was supported by grants: R01 NS 29993, T32 NS 07153.

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