Consensus statement: Carotid Endarterectomy and Angioplasty

1.   Carotid endarterectomy (CEA) has been shown in two major trials (ECST and NASCET) to reduce the risk of stroke in patients with carotid territory TIA or non-disabling ischaemic stroke in the previous 6 months and a severe stenosis of the ipsilateral carotid artery. However, the trial results were not consistent for moderate stenosis, although this may have been due to differences between the trials in the method of measurement of the degree of stenosis and in the definition of outcomes. The individual patient data from these trials and a third trial (VA 309) have now been pooled, normalising for these differences. The NASCET method of measuring stenosis was used in the pooled analysis and is used below.

2.   The benefit of CEA increases with the degree of stenosis, and is substantial for 70-99% stenosis of the symptomatic carotid artery (Grade A evidence): six patients were needed to treat to prevent one ipsilateral stroke (NNT=6; 95% CI 5-9) or any stroke or surgical death (NNT=6; 95% CI 5-10).

3.   The benefit from CEA is lower in patients with 50-69% stenosis than for severe stenosis (grade A evidence); twenty-four patients were needed to treat to prevent one ipislateral ischaemic stroke (NNT=24; 95% CI 13-50), or fourteen to prevent one stroke of any origin, including surgical death (NNT=14; 95% CI 9-35).

      There is no benefit for patients with 30-49% stenosis and surgery is harmful for patients with <30% stenosis (grade A evidence).

 4.  Patients with carotid TIA or non disabling stroke require urgent investigation. This should include history, neurological and cardiovascular examination and imaging of the carotid arteries. CT or MR brain imaging should be done at least in cases with cerebral symptoms but may be omitted for patients with only ocular symptoms. (Results based on post hoc analysis).

 5. The benefit from CEA is highly dependent on time since the presenting symptom. The absolute risk reduction from CEA is reduced by half if surgery is delayed beyond 2 weeks and further reduced by half if it is delayed beyond 4 weeks. (Results based on post hoc analysis).

 6. Other variables in addition to the degree of stenosis and time may be useful in the selection of patients for surgery. This is particularly important for patients with 50-69% stenosis. In patients with 70-99% stenosis benefit is present for all subgroups. In patients with 50-69% stenosis the following variables may influence the benefit of surgery: sex, age, stroke vs. cerebral or ocular TIA and plaque morphology.

     Studies have suggested that other variables may influence the outcome e.g. ultrasonographic composition and morphology of the plaque. Present evidence is at best Grade C and needs to be confirmed.

7.   Although trial evidence is based on catheter angiography, most centres now use duplex ultrasonography in the diagnosis of carotid artery stenosis. Ultrasonographic duplex technique measures the degree of stenosis based on flow velocity with high accuracy, which is improved by a low Doppler angle (<50^o). The degree of stenosis has to be determined by angle specific peak systolic velocity cut off points (see Table 2).

      A repeat ultrasound examination is strongly recommended immediately (the day before surgery) prior to surgery to exclude carotid occlusion and also as part of a quality control.

8.  Surgery is effective for asymptomatic stenosis (Grade A evidence), but the absolute benefit is less than for severe symptomatic stenosis (NNT = 20 at five years for any stroke or surgical death; 95% CI=14-50) according to ACAS.  The large ACST-trial has confirmed the findings of ACAS.: In asymptomatic patients up to the age of 75, immediate CEA halves stroke risk within 5 years from 11.8% to 6.4% (net gain/absolute risk reduction 5.4%, 95% CI 3.0-7.8; p<0.0001; inclusive of 3% perioperative risk). However, before more exact calculations of NNT and health economic implications can be done, 10-year follow-up is necessary to determine if surgery is worthwhile in the long term, particularly in women where there is less information than for men.

           Additional analyses are urgently needed to identify those      

           subgroups of patients with the highest benefit from CEA, greater than the

           average risk for stroke without surgery (2% stroke/year).

 9.    Surgery should be restricted to centres at which the practice and complication rates are regularly monitored by surgeons and neurologists/ stroke physicians, and at which complication rates of surgery are lower or at least comparable to those found in the clinical trials demonstrating efficacy. Monitoring should be prospective and independent of the surgeon involved and should be done with consideration of  the applied indications for surgery and the resulting  case mix at each centre.

10. Carotid angioplasty with or without stenting (CAS) has not yet been properly compared with CEA in terms of safety, effectiveness and durability. Two studies (CAVATAS and SAPPHIRE) were inconclusive of carotid angioplasty vs CEA in both asymptomatic and symptomatic patients The results of other ongoing studies must be awaited before recommending routine carotid angioplasty.

Abbreviations:

ACAS, Asymptomatic carotid atherosclerosis study

ACST, Asymptomatic carotid surgery trial

CAS, Carotid artery stenting

CEA, carotid endarterectomy

TIA, transient ischaemic attack

ECST, European Carotid Surgery Trial

NASCET, North American Symptomatic Carotid Endarterectomy Trial

NNT, number needed to treat

CI, confidence interval

ICA, internal carotid artery

TCD, transcranial doppler

CT,computer tomography

MR, magnetic resonance

PSV Peak systolic velocity

Table 1. Comparison between degree of stenosis for the two large trials

Table 2. Cut-off points for high-grade (>80% ECST; > 70% NASCET) carotid stenosis with regard to insonation angle.