Carotid artery stenting for symptomatic carotid artery stenosis: An early experience in 15 cases

Carotid artery stenting for symptomatic carotid  artery stenosis: An early experience in 15 cases

Ayman A Hassan,a MD; Wagih Fawzy,a MD; Ahmed Abouelnaga,a MD; Ahmed  K Gabr,a MD; Ashraf  A Essa,h MD

a) Department of Vascular Surgery, Ain Shams University, Cairo, Egypt. b) Department of Radiology, Bany Sweif University, Bany Sweif, Egypt.

Abstract

Purpose:  To demonstrate the outcomes of carotid  artery  stenting  (CAS) in treatment of symptomatic patients with significant extracranial carotid artery stenosis (>70%)  as our early experience in 15 cases.

Methods: Between  July 2007 to January  2011, 15 patients  for whom  successful  15 CAS procedures  were done for symptomatic  internal carotid artery stenosis more than 70%, were included in the study. All patients underwent pre-procedural assessment in the form of complete history taking, neurological examination, colour  duplex ultrasonography (CDU) of carotid arteries, magnetic resonance angiography of carotid arteries and diffusion weighted magnetic resonance imaging (DW-MRI) of the brain. After  CAS,  patients  underwent neurological examination at the day of procedure, DW-MRI  ofthe brain  within  72 hours,  and clinical examination and  CDU  of  carotid  arteries at  one  month,  6 months  and  then  annually.

Results: Post- procedural death rate was 6.7%. One patient (6.7%)  developed stroke after

CAS. New DW-MRI lesions of the brain were found in 5 patients (33.3%)  after CAS, four of them (80%) remained  asymptomatic  and were of small volume lesions. Haemorrhagic lesion of the brain was found in one patient (6.7%)  following  CAS and was asymptomatic. Stented carotid arteries remained patent in the remaining 14 survived patients with no new neurologic deficits up to one year of follow up following CAS.

Conclusion: Our early experience in using CAS in treatment of symptomatic carotid artery stenosis is promising. CAS seems to be effective and relatively safe therapeutic option in the short and intermediate terms. However, long term risks remain to be determined. As with other new procedures, it is hoped that with increasing experience, we will be able to better identify patients likely to benefit from the procedure, become more comfortable at catheter manipulation and  thereby  reduce  incidence of technical failures and  complications of the procedure.

Key words: Carotid artery stenosis, carotid artery stenting.

Introduction:

Stroke is the third leading cause of death in the developed countries after heart diseases and cancer.l A significant percentage of strokes are  caused by emboli arising from atherothrombotic carotid artery stenosis which therefore is a risk factor for ischemic stroke.2,3

The international trials have clarified the role of carotid endarterectomy (CEA) in the management of selected patients with symptomatic4,5 and asymptomatic6,7 carotid artery disease. Therefore, CEA has rapidly

been considered as the standard of care of such patients because of its effectiveness and safety.2,5,7

More recently, carotid artery stenting (CAS) which is an endovascular, catheter-based procedure that unblocks narrowing of carotid artery lumen to prevent a stroke, has been proposed  as an alternative to CEA for patients at high risk for surgery. Initially, the success of CAS was limited by a rather high rate of neurological events, mainly related to cerebral embolization;8 post-procedural neurological

complication rates  as high  as 10% were reported  at that time.9 Recently, significant improvement of the endovascular  techniques emerged and the rate of neurological  events has decreased, particularly with  the use of protective devices.10

The largest clinical trial to date, CREST,11 compared CAS  to  CEA  on  the collective incidence of any stroke, any heart attack  or death. They foWld that there were no significant differences out  to four  years  of follow  up between CAS and CEA when counting all three, but CEA has a higher risk ofheart attacks and CAS has a higher risk of minor stroke.

The aim of this study was to demonstrate the  outcomes of CAS  in treatment of symptomatic patients with significant extracranial carotid artery stenosis (>70%) as an  our   early  experience  in   15   cases.

Patients and  methods: Study design:

This study was performed  in two tertiary

referral  centers  in Saudi  Arabia  during  the period between July 2007 and January 2011. We performed  prospective  non randomized study in order to evaluate the outcomes of CAS in  symptomatic patients with  extracranial carotid artery disease as in our early experience. Fifteen patients for whom technically successful

15 CAS procedures were done, were enrolled in the study. Two out of 17 attempted  cases for CAS (11.7%) technically failed  due  to failure to manipulate the carotid artery lesions and were excluded from the study. Technical failure of these two patients did not affect their pre-intervension  neurological status and they were scheduled for CEA. Our indications for treatment were internal carotid artery stenosis of 70% or more4,5,9,11 and the presence of neurological symptoms related to such carotid artery disease. Neurological symptoms in our patients were previous stroke (8 patients) and transient ischemic attacks (7 patients).Patients mean age was 66 years (range 50-85 years). All patients were fully informed about the technical aspects and risks of the procedure, and Wlderwent the followings:

Pre-procedural work up:

- Complete  history  taking  for demographic

data,  cardiovascular risk  factors and neurological symptoms.

- Neurological examination performed by independent neurologist.

- Assessment of the degree of internal carotid artery stenosis and its morphology by colour duplex                 ultrasonography   (CDU) Figure(lA&lB).

- Cervical  and intracranial carotid magnetic resonance  angiography (MRA) to verify the diagnosis of carotid artery stenosis and assess  intracerebral  vasculature.

- Diffusion weighted magnetic resonance

imaging (DW-MRI) of the brain performed

24 hours before the procedure. Post-procedural work  up:

- Neurological examination performed on the day after the procedure.

- DW- MRI of the brain performed within 72 hours after the procedure.

- Clinical and carotid CDU follow up scheduled at one month, 6 months and then annually. The study was approved by the hospitals Ethical Committees and informed consent was

obtained from all patients.

Technique of carotid artery stenting (CAS): The CAS procedure was performed in the angiography unit Wlder local anaesthesia via percutaneous transfemoral access by a team consisting of vascular surgeons and radiologists. Patient monitoring and  management were ensured by an anaesthesiologist. Clopidogrel (75mg) was given at least 3 days before the procedure and a bolus of intravenous heparin (100u!kg) was administered  before selective catheterization of common carotid  artery. A

7F sheath was placed in the common femoral artery  and a 4F catheter  was introduced for selective cannulation of the common carotid artery. Pre-stenting angiography was performed in the lateml, anteroposterior and oblique planes so as to visualize the severity of the stenosis and the intracerebral vasculature Figure(2A). A long 0.035 inch guidewire (Terumo Stiff exchange) was exchanged for a 7F long sheath which was positioned in the common carotid artery. Under road map guidance, the protective filter (EZ-Boston Scientific) was  passed through the internal carotid artery stenosis and deployed at the base of the skull at least 4cm beyond the target lesion. The stenosis was then

dilated with a monorail, 7- or 8-mm diameter,

30-or 40-mm long, self-expanding, metallic

s1ent (Wallstent, Boston Scientific) Figure(lB).

After stent deploym.ent, a balloon was inflated to 5 or 6mm to minimize residual stenosis. The filter  was recaptured. Completion ipsilateral cervical and intracranial carotid angiography was performed to assess technical success and  exclude distal cerebral embolization Figure(lC).Finally, after care of groin puncture site was ensured. Antiplatelet medications consisted of clopidogrel (75m.g) for 3months and aspirin(lOOmg) for life which were given to all patients following the procedure.

Colour duplex ultrasonography (CDU):

All carotid lesions were detectedand imaged by CDU with an ATL 5000 (Philips Medical, Netherlands), using high-frequency probes (4-

7MHz or 5-12MHz). The degree of internal

carotid arteiy stenosis and plaque morphology

{whether  ulcerated  or not and degree of

calcification) were detected  before CAS procedure  together  with   imaging  of contralateral carotid and vertebral arteries. Patients were followed up by CDU following CAS procedme to detectrestenosisof ipsilateral carotid  artery and assess the progress of atherothrombotic disease of the contralateral

carotid and vertebral arteries. Magnetic resonance Imaging (MRI):

Before CAS procedure, a baseline cerebral MRI was obtained with a MAGNETOM Symphony 1.5T magnetic resonance scanner (Siemens AG Healthcare Sector; Erlanger, Germany).The study included MRA of carotid arteries to verify the diagnosis and DW-MRI of thebrainfor presence of old ischemic lesion. Following CAS procedure,another DW- MRI was performed within 72 hours. The presence of new hyperintensity in the brain was interpreted as a sign of a new ischemic lesion after CAS Figore(3A&3B).

Statistical analysis:

Analysis was performed according to intension-to-treat principle. Data  were statistically  described as mean (±SD) or percentages and were compared using student t-test or Chi-square test as appropriate. A p­ value of less than 0.05 was considered significant. Data were collected and tabulated using Microsoft Excel version 7 (Microsoft Cooperation, NY, USA) and analyzed using SPSS for windows ( statistical package for the social science, version ll, SPSS,Inc, Chicago, IL, USA).

Fig.1: Colour duplex  ultrasound of left ca rotid arte ries showing:

A:Lef t i nternal ca rotid artery 80% stenosis (a rrow) with non-ulcerated  plaque.

8:High grade velocity (> 300 ml/second) denoting significant stenosis.

Fig. 2: Left internal carotid arterystenting.

A:Pre·stenting angiogram demonstratinginternal carotid artery stenosis more than 7001o (arrow). B:Stent deployed in the internal carotid artery (arrow).

C:Post stenting angiogram demonstrating successfulinternal carotid artery dilatation withno residualstenosis (arrow).

Results:

The demographic and clinical characreristics of patients are demonstrated in Table(l). They included cardiovascular risk factors with the

male gender, hypertension, diabetes mellitus, dyslipidaemia and coronary artery disease being the most common factors.

Table (1): Patients umographic and clinical charllderistics.

SD:standard deviation; n : number,· BMJ: body mass index.

Lesion characteristics of patients  at CDU examination before CAS procedure are detailed in  Table(2). They  included assessment of

ipsilateral carotid,  contralateral carotid  and vertebral arteries.

Table (2): Lesion characterisdcs at CDU before CAS.

n : number; CDU: colour duplex ultrasonography ; CAS : carotid artery stenting.

Out  of 15 patients who underwent CAS procedure, one patient (6.7%) died in the first post-  procedural day due to myocardial infarction. One patient (6.7%) developed stroke with clinically evident contralateral hemiplegia. CDU examination of the stented carotid artery of this patient revealed patent vessel while his DW-MRI showed a new  large volume hyperintense focus at  ipsilateral cerebral hemisphere. This patient improved within 4 weeks of conservative medical treatment. One patient (6.7%) got  post-procedural groin haematoma which resolved within 3 weeks of conservative treatment. New DW-MRI findings after CAS were found in 5 patients (33.3%). All of these fmdings  were in the ipsilateral cerebral hemisphere and related to the anterior cerebral  circulation. Four of these findings

were of a small lesion volwne with no clinical deficits, while only one of them was of a large lesion volwne  and presented clinically  with contralateral hemiplagia as mentioned before. There  was no correlation between the new DW-MRI findings and pre-intervension carotid artery stenosis degree or plaque morphology.

One  patient (6.7%) showed small haemorrhagic area in post CAS brain DW­ MRI related to the anterior cerebral circulation of ipsilateral hemisphere and was of no clinical neurologic deficits. Clinical results and DW­ MRI  brain  findings following CAS  are summarized in Table(3).

Stented carotid arteries of the remaining 14 survived patients remained patent with no new neurologic deficits up to one year of follow up following CAS.

Fig.3:New diffusion weighted magnetic resonance imaging(DW-MRI} brain lesions after CAS. A:large volume lesion (arrow) presented with contra lateralhemiplegia.

B:Small volumelesions (arrows) which were asymptomatic.

Table (3): Clinical results and DW- MRI brain findings after CAS.

DiJK:ussion:

The purpose of treating a stenosis of the

carotid artery is to prevent stroke and to otherwise redu.ce1he risk of cerebral ischemia. At present, CEA and CAS are accepted as major1herapeutic methods.Nevertheless, CAS has become anattractive1IW:ment for patients because of shorter hospital stays, and the avoidance of general anaesthesia, surgical incision, and the riskof cranial nerve irgwy.9,12

The results of CAS have rapidly improved overtime, and recent controlled series show very low post procedural complication rates comparing  favorably  with  CEA.tl,l3,14

However, the superiority of the endovascular approach still needs to be evidenced and seveml randomized studies are in progress.ll,t s This study represented our early experience

in using CAS as a therapeuticoption furcarotid artery stenosis.Our data showed death rate of

6.7% following CAS. The initial results of

international carotid stenting studyiS,showed death rate of 4% which is lower than that of our study, but of no statistical significance. Other studies reported death rates about (2.1

-5.2%) following CAS.l3,16,17

Our study showed a stroke rate of 6.7% after CAS. Hakan and coworkersl8 reported a stroke rate of 5.4% following CAS which is comparable to our results, while the international carotid stenting studylS reported a stroke rate of 4% which appears tobe lower than that of our findings but of no statistical significance. Initially, post CAS neurological complication rates as high as 10% were reporfed.9 which are significantly higher than that of our results. However,recent controlled series reported stroke rates about (2.1-2.8%) following CAS,11,13,16,17whichare significantly lower than that of our study. This could be explained by the few numbers of cases inour series and that was our early experience.

New DW-MRI brain lesions were found in

33.3% of our patients following CAS, 80% of which was asymptomatic with no additional neurologic deficits. Lacroix and colleagues19 found new DW-MRI brain lesions of 42.6% of patients after CAS, 76.9% of which were asymptomatic, a similar result of our findings. Hakan and coworkers18 reported post-CAS new DW-MRI brain lesions of27% of patients, a comparable result to our findings. However, only 57% of these findings were asymptomatic which are lower than that of our results. Furthermore, Loublad and co-author20 observed past CAS new DW-MRI brain finding in 21% of patients, 50%  of which remained asymptomatic. Our data showed that all of the new DW-MRI lesions were located in the ipsilateral cerebral hemisphere and related to anterior cerebral circulation denoting that all emboli was originating from ipsilateral carotid arteries. However, other studies18,19 reported that some of these new DW-MRI lesion were located at contralateral cerebral hemisphere or related to posterior cerebral circulation denoting that some of emboli was originating from the aortic arch and stated that even the introduction of a guide-wire or catheter into the aortic arch may be deleterious.

There are several reasons why microemboli cause clinically silent lesions or none at all. The total number of emboli and the size and location of DW-MRI lesions seem to be important in determining whether brain lesions become symptomatic or not.21,22 This is true when reviewing our results, we found a DW­ MRI lesion of large volume symptomatic while those of small volume were asymptomatic, a finding reported by others.18,19 No one knows the true clinical  significance of cerebral ischemia that is not associated  with over neurologic symptoms. Heyer and colleagues23 did cognitive testing and found no correlation between DW-MRI findings and neurocognitive dysfunction after CEA. However, long term risks of these silent brain lesions following CAS remain to be determined, a recommendation of other studies)8,19 In our study, stented carotid arteries of the survived patients remained patent  with no new neurologic deficits up to one year of follow up after  CAS. However, we did  not test neurocognitive  functions for those patients

with silent new DW-MRI brain findings following CAS.

Technical failures in our study occurred in

11.7% of the attempted patients for CAS. These patients were scheduled for CEA and were excluded from final results of the study. Technical failure  did not affect the pre­ intervension neurological status  of  these patients.

We know that we have some limitations in our study. This trial is not controlled and is nonrandomized as we tried to select carotid lesions more feasible for CAS especially in our early cases. Also, there were few numbers of cases in our series, 15 cases in about 3.5 years, which reflects poor referral  from neurologists and the belief of people in such community to received medical treatment rather than undergoing such a risky procedure, in their opinion.

Conclusion:

Our early  experience in using  CAS  in

treatment of symptomatic carotid artery stenosis is promising. CAS seems to be effective and relatively safe therapeutic option in the short and intermediate terms. However, long term risks remain to be determined. As with other new procedures, it is hoped that with increasing experience, we will be able to better identify patients likely to benefit from the procedure, become more comfortable at catheter manipulation and thereby reduce incidence of technical failures and complications  of the procedure.

References:

1- Zuromskis T, Wettrholm R, Lindgvist JF, et al: Prevalence of micro-embolic symptomatic high grade carotid artery disease: A transcranial doppler study. Eur JVase Endovasc Surg 2008; 35:534-540.

2- Gasparis AP, Ricotta L, Cuadra SA, et al: High-risk carotid endarterectomy: Fact or fiction.  J Vase Surg  2003;  37: 40-46.

3- Rothwell PM, Wrlow CP: Prediction of benefit  from carotid endarterectomy in individual patients: Risk-modeling study. Lancet 1999; 353: 2105-2110.

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Carotid Surgery Trial : Interim results for