The Egyptian Journal of Neurology, Psychiatry and Neurosurgery

ORIGINAL ARTICLE
Year
: 2016  |  Volume : 53  |  Issue : 4  |  Page : 211--218

Carotid artery stenting in high-risk patients: a single-center experience


Mohamed K Elewa 
 Department of Neurology, Ain Shams University Hospitals, Ain Shams University, Cairo, Egypt

Correspondence Address:
Mohamed K Elewa
Department of Neurology, Ain Shams University Hospitals, Ain Shams University, 38 El-Abbasia, Cairo 11566
Egypt

Abstract

Background Carotid artery stenting (CAS) is a valid alternative to carotid endarterectomy in selected patients. Periprocedural risk of complications is the main determinant for CAS validity. Certain patients’ features may increase the risk of complication. Purpose To assess the management and outcome of the CAS in high-risk patient population. Patients and methods Clinical, treatment, and outcome variables of consecutive high-risk CAS candidates between January 2011 and June 2016 in one center were analyzed. Results Among 29 patients, 21 patients had successful CAS, and only one (3.45%) patient had minor periprocedural stroke. In total, six (20.69%) patients were shifted to carotid endarterectomy, and two (6.90%) patients were managed with medical treatment. Regression analysis showed that bovine arch was independent predictor of CAS infeasibility (P=0.006). The mean follow-up duration was 21.38±15 months. Follow-up duration passed uneventfully. Conclusion CAS in high-risk patients appears to be technically safe. The adverse outcome in high-risk patients is low and accepted. The morbidity and mortality is avoidable with better patient selection and the avoidance of aggressive manipulation whenever possible. CAS should be avoided in patients with certain anatomic risk factors such as type III arch and bovine arch.



How to cite this article:
Elewa MK. Carotid artery stenting in high-risk patients: a single-center experience.Egypt J Neurol Psychiatry Neurosurg 2016;53:211-218


How to cite this URL:
Elewa MK. Carotid artery stenting in high-risk patients: a single-center experience. Egypt J Neurol Psychiatry Neurosurg [serial online] 2016 [cited 2017 Dec 12 ];53:211-218
Available from: http://www.ejnpn.eg.net/text.asp?2016/53/4/211/202380


Full Text

 Introduction



The role of carotid artery stenting (CAS) in the treatment of patient with significant carotid artery stenosis is growing. The outcome of CAS should be defined with respect to standard carotid endarterectomy (CEA), particularly in low surgical risk patients and high CAS risk patients. The identification of the outcome of high CAS risk patients could improve decision making regarding patient selection. Periprocedural risk of CAS is influenced by patient, device, technique, and operator-related factors. Several clinical and anatomic aspects (other than surgical CEA risk factors) have been stated for increased periprocedural CAS risk in literature, including octogenarians [1],[2],[3], difficult anatomy, type II or III aortic arch and bovine arch, tortuous common carotid artery (CCA), angulated Internal Carotid Artery (ICA) origin, angulated distal ICA and tandem intracranial stenosis [4],[5],[6],[7],[8], some lesion characterestics (subtotal occlusion, long lesions ≥15 mm, ostial centered lesions, and calcified lesions) [8],[9],[10], and contralateral carotid occlusion [6]. Our purpose in the current study is to assess the management and outcome of the CAS in the high-risk patient population.

 Patients and methods



A retrospective review of patients who were candidate for CAS procedures between January 2011 and June 2016 in Suez insurance hospital was performed. Study is retrospective so ethical approval is usually not required as according to Egyptian law the patients acceptance of admission includes a consent to retrospective use of their anonymous data. Eligibility criteria included patients with symptomatic carotid stenosis of greater than or equal to 50% measured by angiography in combination with at least one of the high-risk criteria for CAS according to the literature: age greater than or equal to 80, type II aortic arch, type III aortic arch, bovine aortic arch, tortuous CCA, angulated ICA origin, angulated distal ICA, subtotal occlusion (99% stenosis), long lesions (≥15 mm), concentric calcification, ostial centered lesions, and contralateral carotid occlusion or significant stenosis. All patients had carotid duplex ultrasound assessment, including spectral Doppler, color flow, and gray scale, before the intervention (as a screening tool for the candidates). Brain MRI included diffusion-weighted imaging, T1-weighted imaging, T2-weighted imaging, fluid-attenuated inversion recovery imaging, T2*-weighted gradient-echo imaging, and magnetic resonance angiography (time of flight) before the intervention (as a part of the preoperative assessment). A clinical and neurological examination with assessment by modified Rankin Scale (mRS) was performed before and after the intervention and during the follow-up.

Technique of intervention and periprocedural management

Concomitant therapy

Before CAS, all patients were treated with 150-mg acetylsalicylic acid and received a loading dose of 450-mg clopidogrel, if they were not already taking clopidogrel. After CAS, patients were kept on a daily dose of 150-mg acetylsalicylic acid and 75-mg clopidogrel for 4 weeks. Thereafter, only aspirin was given. During the procedure, 100 U/kg of heparin was given for anticoagulation. Before balloon inflation, 0.5-mg atropine was administered to all patients.

Description of the procedure

All cases were performed via the femoral approach. A guide catheter or long sheath was advanced to the CCA. The culprit lesion was visualized in at least two different projections before and after the procedure. The intracranial circulation was visualized in all patients before and after the procedure.

Embolic protection devices

In all patients, a distal embolic protection devices (EPD) was used. We used SpiderFx embolic protection system (ev3 Endovascular Inc., Plymouth, Minnesota, USA).

Carotid stenting

All lesions were treated with self-expandable nitinol stents. The stents were 30–40 mm in length, and the stent diameter ranged from 6 to 10 mm (either tapered or straight). We used Protégé RX Carotid Stent (ev3 Endovascular Inc.). In tight, subocclusive carotid stenosis, predilation was done using low-profile (2–3 mm in diameter) 0.014-inch wire compatible balloons. After stent placement, postdilatation was done using (3.5-5 mm in diameter) balloons. At the end of the procedure, the arterial introducer was removed, and hemostasis was accomplished by manual compression.

Outcome measures and data analysis

All collected patients data either clinical or angiographical were retrospectively revised. Based on these data, patients were included in the study once they had one or more high-risk features for CAS: octogenarian, difficult anatomy (type II or III aortic arch, bovine arch, tortuous CCA defined as vessel kinking of more than 60°, angulated ICA defined as vessel kinking of more than 60°, and tandem intracranial stenosis), some lesion characteristics (subtotal occlusion=99% stenosis, long lesions ≥15 mm, ostial centered lesions, and calcified lesions), and contralateral carotid occlusion or significant stenosis. Technical success was defined as successful treatment of the stenosis with residual stenosis of less than or equal to 30%. Neurologic outcome was evaluated both at the end of the procedure, before discharge, and during follow-up visits in outpatient clinic (monthly for 6 months and yearly thereafter).

The occurrence of neurological, cardiovascular, and puncture-related complications and death was assessed. Neurological complications were classified as one of the following: minor stroke, new neurological deficit with mRS less than or equal to 2 [11], major stroke, new neurological deficit with mRS greater than or equal to 3, transient ischemic attack (TIA), and new neurological deficit that resolves completely within 24 h.

Data were analyzed using statistical program for the social science (IBM SPSS advanced statistics version 20; SPSS Inc., Chicago, IL). Quantitative data were expressed as mean±SD, median, and interquartile range. Qualitative data were expressed as frequency and percentage. The following tests were used: Wilcoxon’s test of significance was used when comparing between related samples in nonparametric data and Binary logistic regression analysis when assisting the anatomic variables which can affect CAS feasibility. In all tests, P-value less than 0.05 was considered significant, P-value less than 0.001 was considered highly significant, and P-value grater than 0.05 was considered insignificant.

 Results



Most of the patients were males. The mean age was 66.31±8.23 years (range: 53–83 years), with 13.8% of the study population older than 80 years. All the patients were symptomatic (defined as amaurosis fugax, TIA, minor stroke, or major stroke) with median mRS of 2 ([Table 1]).{Table 1}

All patients underwent diagnostic digital subtraction cerebral angiography before CAS ([Table 2]). Anatomical difficulties were found in 21 (72.41%) patients.{Table 2}

Of 29 patients eligible for CAS, 21 (72.41%) CAS procedures were done successfully for 21 patients. In total, six (20.69%) patients were shifted to CEA, and two (6.90%) patients were managed with medical treatment. Technical success was achieved in all 21 (100%) complete procedures. Only one (3.45%) patient developed minor stroke (dysarthria and facial paresis) immediately after the procedure, which later improved completely within 2 days ([Table 3]).{Table 3}

The mean follow-up duration was 21.38±15 months. The range of the follow-up period was 3–60 months. Follow-up duration passed uneventfully ([Table 4]).{Table 4}

Patients showed significant change in their mRS at the last follow-up (P=0.003) ([Table 5]).{Table 5}

Regression analysis showed that bovine arch was an independent anatomical predictor of CAS infeasibility ([Table 6]).{Table 6}

 Discussion



CAS is a valid alternative to CEA in selected patients (patients with high risk for CEA). Among CAS candidates, some have high-risk criteria for CAS, which could raise the possibility of adverse outcome. The current study includes patient population with clinical and angioanatomical high-risk criteria for CAS in an attempt to describe their management, decision making, and outcome. The selected high-risk criteria for CAS were based on the previous published literatures.

In the current study, CAS under distal EPD for the presumed high risk for CAS candidates seems to be safe and within the accepted complication rate (periprocedural risk=3.45%). The European and the American guidelines require periprocedural death or stroke rates to be less than 6% in symptomatic patients [12],[13]. The lower rate of complication in our patient population is explained by the use of distal EPD (filter) in all cases. The use of such devices was repeatedly shown to prevent ipsilateral cerebral thromboembolism and subsequent strokes caused by the detachment of particles from carotid plaque during CAS [14],[15]. A systematic review demonstrated a risk reduction in adverse events amounting to 40% during CAS with the use of distal protection devices [16]. Another factor that may contributes in our low complication rate is the low threshold for procedural abortion and the avoidance of aggressive manipulations in some cases with unfavorable anatomy, literally type III and bovine arch; of six (20.69%) patients shifted to CEA for anatomical factors, five (17.24%) patients had anatomically unfavorable arch type (two cases with type III arch and three cases with bovine arch+left-sided lesion). Type of arch was found to contribute to higher stroke rates in six of the seven studies [6],[7],[8]. Wimmer et al. [8] reported that types II and III arches were predictors of stroke following carotid stenting, whereas Werner et al. [7] found the same with bovine arches. Dumont et al. [19] demonstrated that unfavorable arch anatomy, namely a target vessel taking an acute angle off the arch, was a predictor of perioperative stroke risk. In fact, in certain studies, type III aortic arch was contraindicated for CAS [20].

Our observations regarding anatomical high-risk criteria state that certain anatomical factors may hinder CAS feasibility. Bovine arch was found to be a significant predictor (P=0.006) of CAS infeasibility (only one case underwent technically successful CAS of the four cases) ([Table 6]). Type III arch was associated also with CAS infeasibility but was not found to be significant owing to lack of power (only two cases, and both were shifted to CEA). Type II arch was associated with technical difficulty, but all cases were done successfully without complications (three cases). The Carotid Revascularization Endarterectomy versus Stenting Trial 2 (CREST-2) study will compare outcomes in asymptomatic carotid stenosis patients randomized to best medical treatment (BMT) versus CEA plus BMT versus CAS plus BMT, and patients will be excluded from undergoing CAS if they have a type III arch, severely angled or tortuous innominate artery or CCA, or a severely calcified aortic arch [21]. This goes in the same direction with our findings.

In the current study, certain anatomical characteristics [tortuous CCA, angulated ICA origin, angulated distal ICA, and subtotal occlusion (99% stenosis)] and contralateral carotid occlusion or stenosis were associated with technical difficulties, but they did not affect CAS feasibility or outcome.

Tortuous carotid is found on ∼16% of cerebral angiograms [22], which is similar to the rate of 17.24% found in our patient population. Carotid tortuosity represents a challenge in patients undergoing CAS. Myouchin reported that among 31 symptomatic and asymptomatic carotid artery stenosis patients, successful stenting was not possible in two (6.5%) patients because of severe carotid tortuosity (angles of 60° and 73°) [23]. Faggioli et al. [4] and Fanous et al. [24] found that tortuosity of the CCA and proximal ICA were correlated with both technical failure and increased risk of complications. Tortuous carotid prevents safe passage of distal EPD [25]. Severe tortuosity of the carotid artery was found to be an independent predictor of difficult retrieval for distal EPD [26]. Moreover, the periprocedural risk significantly increased in a study of 262 patients with symptomatic carotid artery stenosis when the angulation between the ICA and the CCA exceeded 60° [27]. Similarly, the stroke risk was correlated with severe tortuosity of the CCA and significant angulation of the ICA origin in an unselected population of 751 patients who underwent 833 CAS procedures [7]. In fact, several authors were forced to abort CAS procedures secondary to severe ICA tortuosity [28],[29],[30].

Despite the presence of difficult distal landing zones (distal ICA tortuosity) in seven (24.14%) patients, which provided technical intraprocedural challenges, all had eventual successful deployment and retrieval of distal EPD, and none of our patients required ICA flow reversal. An anatomically difficult distal landing zone not only makes deployment of protection devices more difficult but also makes the retrieval of these devices more challenging [24],[26]. Reimers et al. [31] reported that the distal EPD could not be advanced beyond the lesion in 10 patients owing to high degree of distal ICA tortuosity and lesion severity in a series of 753 patients who underwent 808 CAS procedures. Fanous et al. [24] reported that despite the successful deployment and retrieval of distal EPD in all cases, the presence of hostile anatomy for the deployment of distal EPD was correlated with increased periprocedural risk among 221 symptomatic patients who underwent CAS.

Critical stenosis (>85%) was previously considered by some authors as a contraindication for CAS [20],[32]. Earlier, critical stenosis was technically challenging, as it impeded the safe advancement of distal EPD [25],[29]. With improvement of the available endovascular devices, stenting of such lesion is no more challenging except for subtotal occlusion (99% stenosis). Subtotal occlusion was associated with increased perioperative risk [9],[24]. In the current study, 10 (34.48%) patients had subtotal occlusion, and all had technically successful CAS without any complications ([Figure 1]) except for one patient who was sent for surgery because of absence of clear lumen compatible with safe stenting. This was associated with well-developed vasavasorum crossing the lesion ([Figure 2]).{Figure 1}{Figure 2}

Subtotal occlusion with well-developed vasavasorum crossing the lesion.

Extensive calcification either concentric carotid calcification or aortic arch calcification was associated with increased perioperative risk [24],[32],[33],[34],[35]. They were considered a contraindication for CAS in certain studies [9],[20],[36]. In our study, calcified lesions were found in seven (24.14%) patients. Extensive aortic arch calcification was found in three (10.34%) patients.

Octogenarians in the current study represents 13.8% of the studied patient population (three patients) ([Figure 3]). Fortunately they have favorable angioanatomical characteristics, and we did not face any problem while treating them. The previous observations suggest that increased age may be associated with technical failure and higher rate of complications after CAS procedures [1],[37],[38],[39]. The Carotid Revascularization Endarterectomy versus Stent Trial (CREST) trial reported a periprocedural stroke and death rate of 12% among octogenarians compared with 3.23% for nonoctogenarians [1]. Kastrup et al. [40] also reported a combined stroke and death rate of 10% for symptomatic patients greater than 75 years old. This is compared with a rate of less than 3% stroke and death in patients greater than 75 years old. Interestingly, it has been suggested that complex vascular anatomy is more common in the elderly and that when correcting for complex anatomy, old age was no longer a predictor for poor outcome [30],[33],[41],[42]. This explains the reason of favorable outcome of our octogenarian patients.{Figure 3}

Our decisions were influenced by the special nature of the stenotic lesion in three cases. The first case was of a 53-years-old female patient who was hypertensive and diabetic. She presented with recurrent hemispheric TIA. The carotid duplex showed left-sided high-grade stenosis. Her diagnostic cerebral angiography (DCA) revealed long stenotic lesion (string sign) with areas of aneurysmal dilatation affecting the left ICA from the carotid bulb till the petrous segment secondary to spontaneous dissection ([Figure 4]). Fair collaterals were seen from the left posterior communicating artery. This patient was treated medically with oral anticoagulation plus control of risk factors, with no more ischemic events during follow-up for 6 months. The second case was of a 61-year-old female patient. She had diabetes and chronic liver disease (Child A). She presented with recurrent hemispheric TIAs. Her DCA showed hypoplastic ICA (CT skull base showed smaller ipsilateral carotid canal in comparison with the other side) with 50% circumferential stenosis with multiple significant intracranial tandem lesions ([Figure 5]). There were fair collaterals from the posterior communicating artery. She was treated medically with double antiplatelet therapy (clopedogril 75+ASA 150) plus aggressive control of risk factors, with no more ischemic events during follow-up of 3 years. The third was a 77-year-old diabetic hypertensive female patient. She presented with ischemic stroke. Her DCA showed subtotal occlusion of the left ICA with no clear stenotic lumen with well-developed vasavasorum crossing the lesion ([Figure 2]). This was associated with extensive calcification of the lesion and the arch. The procedure was aborted, and the patient was sent to a vascular surgeon for opinion. We believe that understanding the nature of the lesion and the multidisciplinary approach are seldom important for better decision making. The conservative attitude is always an option when the risk exceeds benefit.{Figure 4}{Figure 5}

 Conclusion



From the previous data, we can conclude that CAS in high-risk patients appears to be technically safe. The outcome of high-risk patients is accepted. The morbidity and mortality is avoidable with better patient selection and the avoidance of aggressive manipulation whenever possible. CAS should be avoided in patients with certain anatomic risk factors type III arch and left-sided lesions with bovine arch. A large prospective study to definitively evaluate the effect of high-risk factors on CAS feasibility and outcome is needed. Several limitations should be considered before generalization of our results. The retrospective nature and the potential patient selection and treatment bias.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interests.

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