9. Prise en charge de la maladie artérielle carotidienne extracrânienne et de l’athérosclérose intracrânienne

L’endartériectomie carotidienne est une intervention chirurgicale destinée à enlever la plaque athérosclérotique de l’artère carotide interne proximale. Une intervention réussie réduit considérablement le risque de récidive d’AVC chez les patients ayant subi un AIT ou un AVC hémisphérique mineur qui présentent une sténose grave de la carotide interne ipsilatérale. Un décès ou un AVC grave est évité pour six patients présentant une sténose carotidienne symptomatique grave (de 70 à 99 %) traités par endartériectomie carotidienne, et un décès pour 22 patients atteints d’une sténose inférieure à 70 % (Rothwell 2004; Orrapin, et coll., 2017). Chez certains patients atteints d’une sténose carotidienne asymptomatique, l’EC fait passer le risque d’AVC d’environ 2 à 1 % par année. Une prise en charge médicale énergique obtient de meilleurs résultats que la pose d’une endoprothèse intracrânienne chez les patients présentant une sténose de 70 à 99 % d’une artère intracrânienne majeure.

Les personnes qui ont subi un AVC et leurs familles ont déclaré avoir reçu des informations minimales sur la sténose carotidienne, et souhaitent en savoir plus, car il s’agit d’un domaine qui ne figure pas souvent dans l’information générale sur les AVC.

1. Protocoles assurant un accès en temps opportun aux services diagnostiques permettant d’évaluer l’état des artères carotides.
2. Élaboration d’ententes et de processus d’accès rapide aux consultations chirurgicales, y compris des mécanismes d’aiguillage accéléré requis en vue d’une intervention carotidienne.
3. Vérification de la prise en charge de l’aiguillage au sein du système pour accroître l’observance des patients. Des mécanismes visant à accroître l’observance devraient être étudiés et évalués.

1. Proportion des patients ayant eu un AVC ou un AIT qui présentent une sténose carotidienne symptomatique modérée à grave (50 à 99 %) et qui subissent une revascularisation carotidienne après l’AVC ou AIT de référence (indicateur de qualité clé).
2. Proportion des patients ayant subi un AVC ou un AIT qui présentent une sténose carotidienne modérée à grave (50 à 99 %), et qui subissent une intervention de revascularisation carotidienne après l’AVC de référence dans les deux semaines suivant la première évaluation à l’hôpital ou à la clinique de prévention de l’AVC (indicateur de qualité clé).
3. Délai médian entre le début des symptômes de l’AVC ischémique ou de l’AIT de référence et la revascularisation de la carotide (jours, heures) (indicateur de qualité clé).
4. Proportion des patients ayant subi un AVC qui nécessitent une intervention sur l’artère carotide et qui subissent la chirurgie moins de deux semaines après l’AVC de référence.
5. Proportion des patients ayant subi un AVC qui présentent une sténose carotidienne modérée (50 à 69 %) et qui subissent une intervention sur l’artère carotide après l’AVC de référence.
6. Proportion des patients ayant subi un AVC qui présentent une sténose carotidienne légère (moins de 50 %) et qui subissent une intervention sur l’artère carotide après l’AVC de référence.
7. Proportion des patients ayant subi une EC et qui sont victimes d’un AVC périopératoire à l’hôpital, d’un infarctus aigu du myocarde ou qui décèdent.
8. Taux de mortalité intrahospitalier dans les 30 jours qui suivent une EC, et taux d’AVC selon le degré de sténose carotidienne.
9. Proportion des patients qui subissent une EC en moins de 2 semaines, de 2 à 4 semaines, de 2 semaines à 3 mois et de 3 à 6 mois après l’apparition des symptômes de l’AVC.
10. Proportion des patients en attente depuis plus de 3 mois d’une EC ou dont la chirurgie a été annulée à cause des longues listes d’attente. Proportion des patients qui subissent un autre AVC ou décèdent pendant qu’ils attendent une EC.

Notes sur la mesure des indicateurs

• Le délai devrait être mesuré à partir de la date de l’apparition des symptômes de l’AVC confirmée par le patient ou un témoin jusqu’à la date exacte de l’intervention chirurgicale.
• L’heure et la date de l’apparition des symptômes de l’AVC sont celles signalées par le patient ou par un témoin fiable au moment de l’épisode.
• L’analyse devrait être stratifiée par « patients recevant une endoprothèse carotidienne » et « patients subissant une EC », par degré de la sténose et par sténose symptomatique ou asymptomatique.
• Sources de données pour la chirurgie : notes chirurgicales, notes du personnel infirmier et résumés produits au moment du congé.
• Dans certains cas, il peut être plus pertinent et approprié de mesurer le délai entre le premier contact avec les soins médicaux et l’intervention chirurgicale. Ce cas se présente par exemple lorsque le patient était à l’étranger au moment de l’AVC et a choisi de revenir au pays avant d’obtenir une intervention médicale définitive. Il importe donc de préciser la nature du moment à partir duquel le délai de traitement ou d’intervention est calculé.

Renseignements destinés aux dispensateurs de soins de santé

• Recommandations canadiennes pour les pratiques optimales de soins de l’AVC – Gestion des AVC aigus, imagerie neurovasculaire
• Questions et réponses du NINDS relativement à l’endartériectomie carotidienne (en anglais seulement)
• University of Oxford, Medical Sciences Division – Outil de sténose carotidienne. Risque à 1 an et 5 ans d’AVC ischémique ipsilatéral prédit par le modèle (en anglais seulement)

Informations destinées au patient

• Cœur + AVC – Liste de vérification après un AVC
• Cœur + AVC – Votre cheminement après un AVC 
• Cœur + AVC – Soutien en ligne et par les pairs
• Cœur + AVC – Athérosclérose
• National Heart, Lung and Blood Institute (en anglais)

Management of Extracranial Carotid Artery Disease and Intracranial Atherosclerosis Evidence Table and Reference List 

Table 9:  Risk of recurrent stroke among patients with carotid stenosis ≥50% and recent stroke awaiting carotid endarterectomy or carotid stenting.

Carotid Endarterectomy

Carotid endarterectomy (CEA) has been shown to be beneficial for preventing stroke recurrence in patients who have sustained a minor stroke or TIA with ipsilateral high-grade carotid stenosis.  There are three large trials comparing endarterectomy for symptomatic stenosis with best medical treatment in such patients: The North American Symptomatic Carotid Endarterectomy Trial (NASCET, 1991), the European Carotid Surgery Trial (ECST, 1998) and the Veterans Affairs Trial (Mayberg et al. 1991). The results of these three trials were pooled in a Cochrane review (Rerkasem & Rothwell 2011).  The risk of any stroke or operative death at 5-years in patients with severe stenosis (70–99%) was significantly reduced in patients in the CEA group (RR=0.53, 0.42-0.67, p<0.0001, NNT=6) with an associated absolute risk reduction of 16.0%. For patients with moderate stenosis (50-69%) the risk was also reduced (RR=0.77, 0.63- 0.94, p=0.001, NNT=22). For patients with mild stenosis, there was no benefit of treatment. Perioperative death or stroke incidence was 7.0% (95% CI 6.2 to 8.0). The greatest benefit of treatment was found in men, patients aged 75 years or over, and patients randomised within two weeks after their last ischaemic event. 

The use of CEA for asymptomatic carotid artery disease is more controversial, given that it is a lower-risk condition. Significant improvements have been made in the medical management of stroke risk factors during the previous 20 years, including the use of statins, antihypertensive agents, and antiplatelets or anticoagulants. Using data from the Asymptomatic Carotid Emboli Study (ACES), which included 477 patients with at least 70% carotid stenosis and no symptoms in the carotid artery territory for at least the previous 2 years, the use of antiplatelet and antihypertensive agents were both significant independent predictors of lower stroke risk or TIA at the end of the follow-up period (King et al. 2013).  There are three large trials that have evaluated the risks and benefits of CEA in the asymptomatic group. The Asymptomatic Carotid Atherosclerosis Study (ACAS) Group, the MRC [Medical Research Council] Asymptomatic Carotid Surgery Trial (ACST) Collaborative Trial and the Veterans Affairs Trial. The results of these trials were pooled in a Cochrane review (Chambers & Donnan 2008). Median duration of follow-up ranged from 2.7-4.0 years. Although the risk of perioperative stroke death was higher in the CEA group (3.0% vs. 0.46%, RR= 6.49, 95% CI 2.53-16.61, p<0.0001), CEA was associated with significant reductions in the risk of perioperative stroke or death or subsequent ipsilateral stroke, (RR=0.71, 95% CI 0.55-0.90, p= 0.0051) as well as stroke or death or any subsequent stroke (RR= 0.69, 95% CI 0.57- 0.83, p<0.0001). The greatest benefits were evident in men and younger patients. There were insufficient data to determine whether increasing degree of stenosis was associated with increasing benefit from surgery. In 10-year follow-up of ACST (Halliday et al. 2010) in which patients were randomized to receive immediate treatment vs. delayed, immediate CEA was associated with a reduced occurrence of stroke at both 5 and 10 years (6.4% vs. 11.8%, p<0.0001 and 10.8% vs. 16.9%, p<0.0001, respectively). The authors concluded that despite a 3% perioperative stroke or death rate, CEA for asymptomatic carotid stenosis reduced the risk of ipsilateral stroke, and any stroke, by approximately 30% over three years, while acknowledging that the absolute risk reduction with carotid endarterectomy is small (1%/year).

Carotid Artery Stenting vs. Best Medical Management

Carotid-artery angioplasty with stenting emerged (CAS) has emerged as an alternative to carotid endarterectomy in patients at high risk for complications for endarterectomy such as contralateral occlusion, advanced age or severe coronary artery disease. The percutaneous approach also avoids the risks of general anesthesia and the local complications of neck hematoma, infection, cervical strain and cranial nerve damage associated with endarterectomy and requires a shorter recovery period. Several large trials assessing the safety and effectiveness of CAS (without the use of embolic protection devices) have been conducted. 

The Stenting and Aggressive Medical Management for Preventing Stroke in Intracranial Stenosis (SAMMPRIS) trial, was the first large open-label clinical trial that randomly assigned patients who had a recent transient ischemic attack or stroke attributed to severe stenosis to receive aggressive medical management alone or aggressive medical management plus percutaneous transluminal angioplasty with stenting (PTAS), using the Wingspan stent system (Chimowitz et al. 2011).  The primary end point was stroke or death within 30 days after enrollment or after a revascularization procedure for the qualifying lesion during the follow-up period or stroke in the territory of the qualifying artery beyond 30 days.  Enrollment was stopped after 451 patients were enrolled because there was a significant increase in the number of patients in the PTAS group had a primary outcome event (20.5% vs. 11.5%, p=0.009). There was also an increased number of patients in the PTAS group who experienced any stroke during the study period (22.3% vs. 14.1%, p=0.03). In the final results (Derdeyn et al. 2014), after a median duration of follow-up period of 32.4 months, fewer patients in the medical group had a primary endpoint event (15% vs. 23%) and the cumulative probability of the primary endpoints was significantly smaller in the medical group (p=0.0252).  A similar trial, Vitesse Stent Ischemic Therapy (VISSIT) was halted after the recruitment of 112 patients, when the negative results from the SAMMPRIS trial became available (Zaidat et al. 2015). Among patients who had been randomized up to that point, the 1-year primary outcome occurred significantly more frequently in patients in the stenting group (36.2% vs. 15.1%, mean difference=21.1%, 95% CI 5.4-36.8%, p=0.02). The risk of stroke recurrence (but not TIA) within one year was also significantly higher in the stenting group (34.5 vs. 9.4%, mean difference 25.1%, 95% CI 10.5-39.6%, p=0.003). More recently, the SPACE-2 trail (Reiff et al. 2019), reported there were no deaths or myocardial infarctions (MI) in any of the study groups (best medical management, CEA and CAS) within 30 days, or in ipsilateral stroke at one year.

Carotid Artery Stenting vs. Carotid Endarterectomy

The risk of periprocedural death and stroke have been shown to be higher following CAS procedures compared with CEA. Zhang et al. (2015) included the results from 35 studies comparing CEA and CAS. Overall, the risk of the primary outcome (stroke or death within 30 days) was significantly higher with CAS (RR=1.51, 95% CI 1.32-1.74, p<0.001). The risk of any stroke or death did not differ significantly between groups at 2 or 3-year follow-up; however, the risk was significantly increased at 4- and 10-years’ follow-up for CAS-treated patients (RR=1.24, 95% CI 1.04-1.46, p=0.01 and RR=2.27, 95% CI 1.39-3.71, p=0.001, respectively). Brott et al. (2019) included the results from 4 RCTs (EVA-3S, SPACE, ICSS and CREST), and reported the risk of stroke or death was increased significantly during the periprocedural and post-procedural periods in the CAS group (11.4% vs. 8.3%; HR=1·45, 95% CI 1·20 to 1·75). The risk difference in the outcome of stroke or death between CEA and CAS favoured the CEA group at 1 year (3.1%), 3 years (2.8%), 5 years (3.0%), 7 years (3.7%) and 9 years (4.1%) after randomization. A recent Cochrane review (Müller et al. 2020) included the results of 22 trials of patients with symptomatic stenosis, who had experienced a minor stroke, those with asymptomatic stenosis or both asymptomatic and symptomatic carotid stenosis. The treatment contrasts included any CEA procedure vs. any endovascular technique (primarily stenting +/- protection devices). Among patients with symptomatic stenosis, stenting was associated with a higher risk of death or any stroke within 30 days of treatment (OR=1.70, 95% CI 1.31- 2.19). In pre-planned subgroup analysis, using data from 6 trials, the risk of periprocedural death or stroke did not differ significantly between stenting and CEA in patients <70 years (OR=1.11, 95% CI 0.74 to 1.64), but was significantly higher in patients ≥70 years treated with stenting (OR=2.23, 95% CI 1.61 to 3.08). The risk of death or any stroke between randomization and 30 days after treatment or ipsilateral stroke until the end of follow-up was also higher in the stenting group.  Among patients with asymptomatic stenosis, the risk of death or any stroke within 30 days of treatment was also significantly higher in those who received a stenting procedure compared with CEA (RR=1.72 95% CI 1.00 to 2.97), while there was no significant difference between groups for the other primary or secondary outcomes. The authors suggested that for patients with symptomatic stenosis, the combined procedural safety and long-term efficacy profile favours CEA, while in patients with asymptomatic carotid stenosis, there may be a small increase in the risk of stroke or death within 30 days of treatment associated with stenting, but further trials are necessary to provide additional data.

The Stent-Supported Percutaneous Angioplasty of the Carotid Artery versus Endarterectomy (SPACE) Trial included 1,200 patients, with symptomatic carotid artery stenosis, who had experienced TIA or moderate stroke within 180 days and with severe carotid artery stenosis (≥ 50% according to NASCET) (Ringleb et al. 2006). Patients were randomized to receive CAS (27% used embolic protection devices) or CEA after a median delay of 4-5 days. The trial was stopped prematurely due to concerns regarding funding and futility. There were no differences between groups on either any of the primary outcomes of 30-day ipsilateral stroke or death, or any of the secondary outcomes (disabling stroke or death from any cause within 30 days, disabling stroke, or procedural failures).

The Asymptomatic Carotid Trial (ACT 1) (Rosenfield et al. 2016), a noninferiority trial was stopped early due to slow enrolment. While the protocol aimed to recruit 1,658 patients, data from only 328 patients were available for follow-up assessment at 5 years. At one year, the occurrence of the primary outcome (composite of death, stroke, or myocardial infarction within 30 days of the procedure or ipsilateral stroke within 1 year of the procedure) was 3.8% for stenting group compared with 3.4% for CEA group. The threshold of a 3%-point difference for inferiority was not exceeded (upper 95% CI for difference was 2.27%), suggesting that CAS was not inferior to endarterectomy. Survival from 30 days to 5 years was not significantly different between groups (87.1% stenting group vs. 89.4% CEA group, p=0.21). 

The International Carotid Stenting Study (ICSS) trial enrolled 1,713 patients >40 years, with symptomatic carotid artery stenosis ≥50% using the NASCET criteria (Ederle et al. 2010). Between randomization and 120 days, stenting was associated with an increased risk of stroke, death or procedural myocardial infarction, (8.5% vs. 5.2%, HR=1.69, 95% CI 1.16-2.45, p=0.006) any stroke (7.7% vs. 4.1%, HR=1.92, 95% CI 1.27-2.89, p=0.002), any stroke or death (8.5% vs. 4.7%, HR=1.86, 95% CI 1.26-2.74, p=0.001) and all-cause mortality (2.3% vs. 0.8%, HR=2.76, 95% CI 1.16-6.56, p=0.017).  In the long-term study analysis Bonati et al. (2015) reported that after a median duration of 4.2 years the risk of any stroke was significantly increased in the stenting group (HR=1.71, 95% CI 1.28 -2.3, p=0.0003), while stenting was not associated with an increased risk of fatal or disabling stroke (HR=1.06, 95% CI 0.72-1.57, p=0.77). There was also a significantly increased risk of the outcome of periprocedural stroke/procedural death or ipsilateral stroke during follow-up (HR=1.72, 95% CI 1.24-2.39, p=0.001).). In both the per protocol and intention-to-treat analyses, the cumulative 5-year stroke risk was significantly higher in the stenting group (HR=1.53, 95% CI 1.02-2.31 and HR=1.71, 95% CI 1.28-2.30, respectively), while the 5-year risk of fatal or disabling stroke was not increased. The distribution of modified Rankin Scores was similar between groups.  

The Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) trial included 2,502 patients with asymptomatic or symptomatic carotid artery stenosis who had experienced a minor stroke or TIA within the previous 180 days (Brott et al. 2010). The primary end point was the composite of any stroke, myocardial infarction, or death during the peri-procedural period or ipsilateral stroke within four years after randomization. There was no significant difference in the estimated four-year rates of the primary end point between groups (7.2% vs. 6.8%); however, the 4-year rate of stroke or death was higher in the stenting group (6.4% vs. 4.7%, HR=1.50, 95% CI 1.05-2.15, p=0.03).  During the periprocedural period, there was a significantly increased risk of stroke or death associated with stenting, but no difference in risk for stroke, death or MI between treatment conditions from 31 days to end of follow-up. After the 30-day, periprocedural period, incidence of ipsilateral stroke was similarly low in both groups (2.0 vs. 2.4%, p=0.85). At 10 years, there was no significant difference between groups in the risk of the primary outcome, which included stroke, death or MI (HR=1.10, 95% CI 0.83-1.44, p=0.51), or in the risk of stroke between groups (HR=0.99, 95% CI 0.64-1.52) (Brott et al. 2016).

Timing of Revascularization Procedures

When indicated, revascularization procedures should be performed as soon as possible following minor stroke or TIA; ideally, within 14 days. Without these procedures, the risk of recurrent events is high. Johansson et al. (2013) reported the overall frequency of ipsilateral ischemic stroke recurrence before CEA was 18.6% in the ANSYSCAP study. The frequency of ipsilateral ischemic stroke recurrence was 5.2% within two-days, 7.9% within 7days, and 11.2% within 14 days of the presenting event. Johansson et al. (2016) included 377 patients with symptomatic carotid stenosis (50-99%), who were eligible for CEA or CAS. Of these, 51 patients had an ipsilateral ischemic stroke or retinal artery occlusion within 90 days. The percentage of patients who experienced recurrent events increased with time of delay from event to procedure (1 day, 2.7%; 3 days, 6.6%; 14 days, 11.5%; 30 days, 13.7% and 90 days: 18.8%). The pattern of results was similar for the outcome of disabling or fatal stroke.

Hospital and Operator Volumes

Increasing experience of an operator or hospital has been shown to reduce the number of adverse events. Poorthuis et al. (2019) included the results of 87 studies examining the association between operator or hospital volumes and outcomes after carotid revascularization procedures. The risk of the primary outcome (procedural death or stroke within 90 days) was significantly lower among high-volume operators following both CEA and CAS procedures (CEA: unadjusted RR=0.59, 95% CI 0.42–0.83; 9 cohorts and CAS: unadjusted RR=0.50, 95% CI 0.32–0.79; 1 cohort), although there was wide variability in the descriptions of low and high-volume operators.

Cervical Artery Dissection

While the incidence of cervical artery dissections (CeAD) is relatively low, estimated to be between 2.6 to 2.9 per 100,000, CeAD is over-represented among persons less than 45 years (Weimar et al. 2010). Given the increased risk of recurrent stroke associated with CeAD, treatment with either antiplatelets or anticoagulants for at least 3 months is recommended. Based on the results of the Cervical Artery Dissection in Stroke (CADISS) Study (Markus et al. 2015), treatment with either agent appears to be equally effective for the prevention of recurrent stroke. In this trial, 250 patients with extracranial carotid or vertebral artery dissection were randomized, within 7 days of the event, to receive antiplatelet agents (dipyridamole, aspirin or clopidogrel, alone or in combination) or anticoagulant therapy (UFH, LMWH, followed by warfarin, with a target INR of 2-3), for the study duration. At the end of 3 months, the frequency of the primary outcome (stroke or death), was similar between groups. There were 4 recurrent strokes (3 antiplatelet vs. 1 anticoagulant) and no deaths in either group. There was a single case of major bleeding in the anticoagulant group. At one year (Markus et al. 2019), the risks of ipsilateral stroke, ipsilateral stroke or TIA, any stroke or TIA, or any stroke or death were similar between groups in both the intention-to-treat and per-protocol analyses. Among 181 patients who had MRI or CTA imaging performed at baseline and repeated at 3 months, there was no difference in the presence of residual narrowing or occlusion between those receiving antiplatelet therapy (n = 56 of 92) vs those receiving anticoagulant therapy (n = 53 of 89) (p = .97).

Similar findings were reported in a meta-analysis including the results of 34 non-randomized studies examining the same treatment contrast (Menon et al. 2008). There were 13/185 (7.0%) in the antiplatelet group and 17/447 (3.8%) in the anticoagulant group who suffered a TIA or stroke. The risk difference between groups was not significant (5%, 95% CI -1% to 11%, p = 0.11). The use of novel oral anticoagulants (NOAC) for the prevention of recurrent stroke following CAD has not been well studied. There are no RCTs to date. In a retrospective study (Caprio et al. 2014) including 149 patients with CAD, who were prescribed antithrombotic medication at hospital discharge, there were 2 recurrent strokes during a median of 7.5 months follow-up in the NOAC group compared with one each in the anticoagulant (AC) and antiplatelet (AP) groups. There were significantly fewer major hemorrhagic events in the NOAC group (0 vs. 8 [AC] and 1 (AP], p=0.034).