Servier – Phlebolymphology

Risk stratification methods for asymptomatic carotid plaques.
S. Kakkos

The incidence of stroke, in patients with asymptomatic carotid artery stenosis >60% randomized to the medical arm of the ACAS (Asymptomatic Carotid Atherosclerosis Study) and ACST (Asymptomatic Carotid Surgery Trial) studies, has been shown to be 2% per year, while in the surgical arm, carotid endarterectomy, in carefully selected patients, reduces the risk of stroke to 1% per year. Therefore, 100 surgeries are needed to prevent one stroke in one year, so up to 94% of the interventions may not benefit the patient. Additionally, the improving results of the current medical therapy have further challenged the need for intervention in asymptomatic carotid stenosis. Therefore, it is imperative to be able to identify the patients at high risk for cerebral ischemic events. Subsequently, it has found that factors associated with a high risk of stroke include clinical characteristics (hypertension, age over 70, male sex, history of contralateral neurological symptoms, and hypercholesterolemia), stenosis characteristics (increasing severity of carotid stenosis, progression of carotid stenosis over time, and contralateral carotid artery occlusion), and plaque characteristics (plaque ulceration, unstable carotid plaque morphology [based on ultrasound], plaque echolucency, discrete echogenic plaque components, low gray-scale median, large plaque area, discrete white areas, and juxtaluminal black areas). However, the decision to intervene should be based not only on risk stratification alone, but also on the anatomical characteristics of the stenosis, patient fitness for surgery and expected survival, the perioperative stroke and death rate of the surgeon, and the willingness to take the small short-term risk of surgery for a possible greater long-term benefit. The ACSRS study (Asymptomatic Carotid Stenosis and Risk of Stroke) has reported that the severity of stenosis and the neurological history of the contralateral carotid and ultrasonic plaque features are independent powerful predictors of plaque instability and future stroke (Kakkos S et al. J Vasc Surg. 2014;59(4):956-967). These plaque features include the presence of juxtaluminal black areas and discrete white areas. High-risk groups with an annual 4% to 10% risk of stroke and a low-risk group (<1% annual risk) were identified. The latter group can be spared from carotid intervention and efforts concentrated toward aggressive medical management and patient follow-up.

The author concluded his talk suggesting, for the near future, a more common use of software for ultrasound image analysis, as this can provide not only the percentage of a carotid stenosis, but also its annual stroke risk.

CEA versus CAS: the latest RCT evidence.
L. Bonati

Randomized controlled trials (ICSS [International Carotid Stenting Study]; EVA-3S [Endarterectomy Versus Angioplasty in Patients With Symptomatic Severe Carotid Stenosis]; SPACE [Stent-Protected Angioplasty versus Carotid Endarterectomy]; and CREST [Carotid Revascularization Endarterectomy versus Stenting Trial]) consistently demonstrated a higher risk of periprocedural nondisabling stroke with stenting than endarterectomy for treatment of symptomatic carotid stenosis. However, several factors differentially modify the periprocedural risks of the two treatments: an excess stroke risk with stenting over endarterectomy has most consistently been demonstrated for elderly patients, and more recently, patients with cerebral white matter disease and possibly those treated early after the initial cerebrovascular event. In addition, operator and procedure-related risk factors have been identified for stenting: periprocedural stroke risk is higher for stents with open-cell than closed-cell design and decreases with higher current volume of procedures performed by the operator. The clinical relevance of silent periprocedural complications is increasingly recognized: elevation of heart enzymes without other symptoms or signs of myocardial infarction, which is more common after endarterectomy, increases long-term mortality. Silent brain infarction on the other hand, which is more common in stenting, appears to increase the risk of recurrent clinically manifest cerebrovascular events in the short-term. Long-term follow-up to 10 years after randomization in the ICSS trial reveals equal efficacy of stenting and endarterectomy in preventing fatal or disabling stroke, the trial’s primary outcome measure, and shows no difference in patients’ functional ability between the two procedures. There is also no difference in long-term risk of severe restenosis or occlusion of the carotid artery after completed treatment between the two arms. The author concluded that the choice between the two procedures in treating patients with symptomatic carotid stenosis is therefore best guided by factors influencing periprocedural risks, like age, white matter disease, open-cell stents, and low case volume for carotid artery stenting.

CEA. Shunting and contralateral carotid occlusion: never, always, or in selected cases?
J. Cronenwett

The author started by placing some questions regarding carotid endarterectomy (CEA) in the setting of contralateral carotid occlusion (CCO). Is the stroke rate higher during CEA? Are shunts required more frequently? Should a shunt be placed in all patients with CCO?

Even though the stroke rate was higher for CEA with CCO in the NASCET trial (North American Symptomatic Carotid Endarterectomy Trial), in the ACAS trial (Asymptomatic Carotid Atherosclerosis Study), it was not, and multiple smaller studies showed different outcomes. Meanwhile, a meta-analysis published in 2013, gathering 25 726 patients (Antoniou GA et al. J Vasc Surg. 2013;57:1134-1145), verified that the stroke rate is actually 1.5 to 1.7 times higher for CEA with CCO, with important variations in shunt use between local and general anesthesia. A recent study showed that shunt requirement had an odds ratio of 4.3 in the CCO setting (Pennekamp CW et al. Eur J Vasc Endovasc Surg. 2013;46:631-637).

Subsequently, he presented his study that investigated the association between surgeon practice pattern in shunt placement and 30-day stroke/death in patients undergoing CEA with CCO. Among 6379 primary isolated CEAs performed in the Vascular Study Group of New England (VSGNE) between 2002 and 2009, 353 patients were identified who underwent CEA in the setting of a CCO. They examined 30-day riskadjusted stroke or death rate across the reason for shunt placement (no shunt, shunt placed routinely, and a shunt placed for an indication) as well as 2 distinct surgeon practice patterns in shunt placement (surgeons who selectively utilize a shunt (0% to 95% of their CEAs), or routinely utilize a shunt (>95% of their CEAs). Of 353 patients with CCO, 33% underwent CEA without a shunt, 49% underwent CEA using a shunt placed routinely, and 18% had a shunt placed for a specific indication. There were no significant differences in rates of 30-day stroke or death across the categories for the reason for shunt use (3.4%, no shunt; 4.0%, routine shunt; 4.8%, shunt for indication; P=0.891). However, across surgeon practice pattern in shunt use, the risk of 30-day stroke or death was higher for surgeons who selectively placed shunts and lower for surgeons who routinely placed shunts (5.6%, selective; 1.5%, routine; P=0.05). Stroke/ death rates were lowest when individual surgeons’ intraoperative decisions reflected their usual pattern of practice: 1.5% stroke/death rate when “routine” surgeons placed a shunt, 3.4% when “selective” surgeons did not place a shunt, and 7.6% stroke/death rate for “selective” surgeons who placed a shunt (P=0.05 for trend; Goodney PP et al. J Vasc Surg. 2012;55:61-71).

The author concluded that shunt use for CCO during CEA is associated with fewer complications, but only if the surgeon uses a shunt as part of his or her routine practice during all CEAs under general anesthesia. When local anesthesia is applied, a shunt should only be placed for neurologic deficit.

CAS. My favorite stent is…?
M. Bosiers

In an endovascular treatment, the plaque is being contained by a stent and not removed as in carotid endarterectomy. At the end of the procedure, after removal of the embolic protection device (EPD), the stent is the only protector.

In this context, scaffolding (ie, plaque containment) is perhaps the most important feature of a carotid stent and an open-cell design allows higher prolapse of the plaque, especially in tortuous curvature (“fish scaling”). As a result, open-cell stents are significantly more prone to induce new ipsilateral lesions than closed-cell stents (Schnaudigel S et al. Stroke. 2008;39:1911-1919). For this reason, the Wallstent (Boston Scientific) and the Xact stent (Abbott Vascular) are good candidates for the treatment of (mainly symptomatic) carotid lesions because of their high scaffolding characteristics.

The choice of the stent is also determined by the arterial anatomy and the morphology of the lesion. Due to this reason, the conformability, vessel wall adaptability, and radial force are also important factors for the choice of an ideal carotid stent. Conformability is a significant feature to maintain the original anatomy. In fact, a rigid stent may cause a distal kinking. The ability to adapt to the vessel wall is also quite relevant, especially when the difference in diameter between common and internal carotid artery is high. Additionally, a carotid stent needs to have sufficient radial force to be able to resist elastic recoil and radial crush, but excessive radial force may promote intimal hyperplasia or cause plaque disruption in vulnerable lesions.

Meanwhile, new developments in carotid stent technology must combine the high scaffolding characteristics with an ideal conformability, vessel wall adaptability, and radial force. The need for flexible, maximally scaffolding stents that have the potential for reducing the late emboli, is obligatory to revive the carotid artery stenting procedure. In this context, two new stents are in the pipeline: the Terumo Roadsaver and the Gore carotid stent.

As these new devices appear to be promising tools for the treatment of carotid artery disease, the favorite stent for the author is not on the market yet.