Is angiography still the best method to stratify stroke risk in symptomatic atherosclerotic carotid plaque?

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Vol.2, No.8, 470-472 (2013) Case Reports in Clinical Medicine

http://dx.doi.org/10.4236/crcm.2013.28124

Is angiography still the best method to stratify stroke

risk in symptomatic atherosclerotic carotid plaque?

Gustavo W. Kuster1*, A. J. Da Rocha2, A. S. F. Silva2, R. A. Valiente3, M. S. G. Rocha3,

A. R. Massaro4

1Division of Neurology, São Paulo University, São Paulo, Brazil; *Corresponding Author: [email protected]

2Department of Radiology and Pathology, Fleury Institute, São Paulo, Brazil

3Division of Neurology, Santa Marcelina Hospital, São Paulo, Brazil

4Sao Paulo University, São Paulo, Brazil

Received 20 June 2013; revised 18 July 2013; accepted 25 August 2013

Copyright © 2013 Gustavo W. Kuster et al. This is an open access article distributed under the Creative Commons Attribution Li-

cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

The degree of vessel lumen narrowing is an

independent predictor of ischemic stroke. New

development s in carotid plaque m orphology imag-

ing (MR, CT), may bring new insights to the re-

lationship between carotid atherosclerotic di-

sease and stroke risk. Our aim is to review the

stroke risk in a symptomatic patient with moder-

ate carotid stenosis by CT imaging and histo-

pathology. A 72-year-old patient with low ABCD2

scores TIA and moderate left internal carotid

stenosis (50% by carotid ultrasound), was dis-

charged with an optimized medical therapy.

Four months later, he presented an ischemic

stroke in the left frontal area. Carotid angi-

ography showed a 60% stenosis in the left-

internal carotid artery with a regular surface. CT

plaque imaging detected a thin fibrous cap with

calcification and an intraplaque hemorrhage (high-

risk plaque). These findings were confirmed in

the histolopathological study of the atheroscle-

rotic plaque performed after the endarterectomy.

After 1 year of follow-up, the patient returned

independently to his daily activities. We propose,

in this stud y, the inclusio n of nonin vasive p laque

imaging in the evaluation of acute TIA with

moderate carotid stenosis to better select pa-

tients with higher risk of stroke recurrence.

Keywords: Carotid Atherosclerotic Plaque; CT;

Plaque Classification

1. INTRODUCTION

Carotid atherosclerotic plaque has been identified

since our ancient ancestors and some in the recent

modern era have been evaluated to the prevention of

catastrophic stroke [1]. The report from North America

Symptomatic Carotid Endarterectomy Trial (NASCET)

in 1991 has stimulated new interest in carotid stenosis

and confirmed angiography as a gold standard method to

stratify symptomatic patients to endarterectomy [2].

The degree of vessel lumen narrowing is an indepen-

dent predictor of ischemic stroke, particularly in sympto-

matic patients with severe carotid stenosis (70%). Ca-

rotid endarterectomy is also associated with a moderate

stroke risk reduction in patients with symptomatic

moderate carotid stenosis (50% - 69%). However, treat-

ment decisions in these cases should be also considered

as other important issues including an exceptional sur-

gical skill [3]. In addition, opti mal medical treatment has

been improved and becomes a topic of equal impor-

tance for managing carotid disease, especially in those

patients with asymptomatic atherosclerotic plaque [4].

New developments in carotid plaque morphology

imaging, particularly MR or CT, may bring new insights

to the relationship between carotid atherosclerotic di-

sease and stroke risk [5,6].

Our aim is to review the stroke risk in a symptomatic

patient with moderate carotid stenosis according to the

plaque surface morphology and the degree of stenosis on

carotid angiography and to compare the carotid plaque

morphology classification obtained by CT imaging and

histopathology.

2. CASE

A 72-year-old previously hypertensive patient arrived

at emergency department with a sudden onset of right

sided weakness lasting 10 minutes. He was evaluated

using the TIA assessment protocol and obtained a low

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G. W. Kuster et al. / Case Reports in Clinical Medicine 2 (2013) 470-472 471

ABCD2 score. The only remarkable finding was a

proximal moderate left internal carotid stenosis (50%)

detected by the carotid ultrasound examination. He was

discharged and referred to the neurological outpatient

clinic with an optimized medical therapy.

Four mouth later, he presented a recurrence of similar

symptoms without a complete recovery (NIHSS = 2) and

arrived at hospital outside of the therapeutic window for

reperfusion. Brain MRI demonstrated an ischemic stroke

lesion in the corona radiata and frontal cortex visible in

the FLAIR and T2-weighted imaging. Carotid angio-

graphy showed a 60% stenosis in the left proximal

internal carotid artery with a regular surface (Figure

1(A)). CT plaque imaging (Figure 1(B)) detected a thin

fibrous cap with calcification and an intraplaque hemorr-

hage (Figure 1(C)) classified as a high-risk plaque ac-

cording to the American Heart Association plaque

classification [7]. These findings were confirmed in the

histolopathological study of the atherosclerotic plaque

(Figure 1(D)) performed after the endarterectomy. After

1 year of follow-up, the patien t returned indep enden tly to

his daily activities (modified Rankin score = 1).

3. DISCUSSION

Carotid ultrasound is usually the first line exa mination

to evaluate carotid disease in patients with TIA and

Figure 1. (A) Digital Subtraction Angiography with 60% bulb

carotid stenosis, according NASCET criteria, and regular

surface (arrow). (B,C) Contrast CT carotid plaque imaging with

a thin fibrous cap (green), calcification (blue), rich lipid ne-

crotic core (yellow) and intraplaque hemorrhage (red). (D)

Histological sample (HE, ×400) of pos endarterectomy carotid

plaque confirming hemorrhage (arrow).

detects a stenosis degree in the lower limit of the range

(50%) for a clinical decision in favor of carotid endarte-

rectomy in our patients.

Carotid angiography performed in the recurrent

ischemic event did not significantly add new information.

We hypothesized that the stenosis grade obtained (60%)

might have changed during the interval between the two

ischemic events due to dynamic modification in the

structure and have turned into a high risk plaque. CT

plaque imaging identified features beyond luminal ste-

nosis or plaque surface and represented a new non-

invasive imaging technique that might reliably assess

plaque vulnerability in symptomatic carotid disease pa-

tients presenting with an acute ischemic event. Based on

histological American Heart Association criteria, the

classification allows categorization of carotid plaques

noninvasively into distinct lesion types (I-VIII). Athero-

sclerotic plaques that are prone to rupture owing to their

intrinsic composition such as a large lipid core, thin

fibrous cap and intraplaque hemorrhage are associated

with subsequent thromboembolic ischemic events as oc-

curred in our patients.

CT plaque imaging classification worked less well for

classifying lipid-rich necrotic cores and hemorrhage,

probably because the range of densities associated with

these components overlapped with the densities as-

sociated with connective tissue, but they showed a good

correlation with histological classification when only

large lipid core and large hemorrhage are considered [5].

On the other hand, MRI has also some limitations in the

acute stroke evaluation and needs a specific phased-array

surface coil for plaque examination [6].

Timing of carotid endarterectomy after an ischemic

event may largely influence outcome. Therefore, we

propose the inclusion of noninvasive CT plaque imaging

in the evaluation of acute TIA with moderate carotid

stenosis to better select patients with high er risk of strok e

recurrence.

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