Stroke is the third leading cause of death in the western world. With the presentation of the preliminary results of the Asymptomatic Carotid Stenosis and Risk of Stroke (ACSRS) study and the SAPPHIRE trial at the American Heart Association meeting, two questions emerged: Is there a mandate for intervention for patients with asymptomatic carotid stenoses? Is carotid endarterectomy (CEA) still the gold standard treatment to reduce stroke?
Asymptomatic carotid stenoses
From meta-analysis (by Benavente et al), there is evidence that carotid endarterectomy in patients with severe asymptomatic carotid stenosis is seen to reduce the incidence of stroke. However, a minimum of 100 operations needs to be performed to prevent one stroke per year. This means that surgeons are operating unnecessarily on many patients, with over 50% of the CEA procedures performed on asymptomatic patients according to reported series. At present, they are unlikely to change their practice. What is needed is the identification of the subset of those who are at high risk (>4% stroke incidence pa). Even more important is to identify those at low risk (<1% pa) and spare them from an unnecessary operation that carries an inherent mortality and morbidity risk.
The objectives of the ACSRS study were several: Firstly, to identify a subgroup of patients with asymptomatic carotid stenosis at risk of ipsilateral stroke greater than 4% pa. Secondly, to identify a subgroup of patients with a risk of ipsilateral stroke less than 1% pa. Thirdly, to identify and standardise non-invasive tests or combinations of such tests and appropriate criteria that can achieve the first and second objectives.
It seems clear that there are other factors other than the degree of stenosis that is important for the prognosis and that echolucent carotid plaque is more dangerous. However, the evidence that high-risk sub-groups can be identified based on plaque morphology comes from cross-sectional studies using subjective imaging methods rather than longitudinal studies. For instance, a recent prospective study carried out in Denmark failed to identify via plaque-type whether to do surgery in asymptomatic patients.
At the American Heart Association meeting Andrew Nicolaides, the scientific co-ordinator of the ACSRS study, presented its data. 1,058 individuals with asymptomatic carotid stenosis (50-99% ECST) were admitted into the ACSRS natural history study. So far follow-up has been between 0.5 and 5 years. Stenosis was 50-69% in 178 and 70-99% in 870 patients. There have been 267 (25%) cardiovascular events including 81 (7.6%) cardiovascular deaths and 135 (12.7%) cerebrovascular events of which 94 (8.8%) were ipsilateral (AF=21, TIAs=36, strokes=37). Using a Cox proportional hazard model, the degree of stenosis (50-69%, 70-89%, 90-99%) (p=0.04), type of plaque (Geroulakos classification: 1-5, p=0.001), duration of hypertension in years (p=0.002) and clinical recruitment (medical or surgical, p=0.008) were independent predictors of risk for ipsilateral stroke. The type of plaque was a stronger predictor than the degree of stenosis.
Nicolaides said that according to the Asymptomatic Carotid Atherosclerosis Study (ACAS) criteria (stenosis NACSET > 60% or ECST > 77%) 612 (58%) of the 1,058 patients should have been considered for CEA. “On the basis of our [ACSRS] model only 210 (20%) (upper quintile) could be identified as having a five-year cumulative stroke rate of 21% (4.2% per year) and could be considered for CEA. The remaining had a five-year cumulative stroke rate of less than 3.3% (<0.6% per year) (log-rank, p< 0.01). Thus, using the new criteria, only six operations need to be performed to prevent one stroke in five years and two-thirds of patients at low risk can be spared from an unnecessary operation.
This finding implies that two-thirds of procedures could be avoided. The impact of this would be to cut the number of asymptomatic carotid endarterectomies in the US from 90,000 to 30,000, saving the health care services approximately $1 billion per year.
Armed with these data Giorgio Biasi will argue that there is a mandate for intervention for patients with asymptomatic carotid stenoses at the 25th Charing Cross Symposium next year and that “the automatic exclusion from a surgical programme of an asymptomatic patient, would not be entirely ethical and to his/her clinical interest.
Carotid stenting gets a double boost
Also presented at the American Heart Association meeting were the 30-day interim findings for the SAPPHIRE study (a clinical investigation of Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy).
Of the 307 patients in the randomised arm of the study, 156 received Cordis’Precise nitinol self-expanding stent – in combination with the Angioguard or Angioguard XP Emboli Capture Guidewire. The remaining 151 patients underwent CEA. At 30-day follow up, the major adverse event (defined as death, stroke or myocardial infarction) rate for the randomised stented group was 5.8% versus 12.6% for the endarterectomy-treated patients, a statistically significant improvement.
Jay Yadav, Director of Peripheral and Carotid Interventions at the Cleveland Clinic Foundation and SAPPHIRE trial investigator, said: “While these results are preliminary, the 30-day data are a good barometer of long-term results. Most procedure-related adverse events in carotid artery intervention occur within this timeframe.
In addition to the randomised group, the SAPPHIRE study enrolled 409 patients into a stent registry. These were patients who required treatment but were determined by their multidisciplinary treatment team, which included at least one vascular surgeon, not to qualify for CEA.
Shortly after the American Heart Association, Giorgio Biasi presented the final results of the ICAROS Study (Imaging in Carotid Angioplasty and Risk of Stroke). The purpose of the study was to see whether it is possible to reduce the neurological complications of carotid stenting by correlating the risk of embolization with the echographic characteristics of the carotid plaque on the basis of a duplex scan.
Over 400 patients from 12 centres were entered into the study and there were neurological complications in 6.6% of patients. Biasi reported that 71.4% of the complications occurred in cases with the duplex scan with a Grey Scale Median assessment (GSM) of less than 25 (very soft echolucent plaque) and embolic particles were collected in only 15% of cases in patients with a GSM of greater than 25.
The conclusion of the ICAROS study was the need to look at the GSM of the plaque as well as the more conventional parameters such as the degree of stenosis or symptoms before deciding to carry out carotid stenting. Carotid stenting gets a double boost
Also presented at the American Heart Association meeting were the 30-day interim findings for the SAPPHIRE study (a clinical investigation of Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy).
Of the 307 patients in the randomised arm of the study, 156 received Cordis’Precise nitinol self-expanding stent – in combination with the Angioguard or Angioguard XP Emboli Capture Guidewire. The remaining 151 patients underwent CEA. At 30-day follow up, the major adverse event (defined as death, stroke or myocardial infarction) rate for the randomised stented group was 5.8% versus 12.6% for the endarterectomy-treated patients, a statistically significant improvement.
Jay Yadav, Director of Peripheral and Carotid Interventions at the Cleveland Clinic Foundation and SAPPHIRE trial investigator, said: “While these results are preliminary, the 30-day data are a good barometer of long-term results. Most procedure-related adverse events in carotid artery intervention occur within this timeframe.
In addition to the randomised group, the SAPPHIRE study enrolled 409 patients into a stent registry. These were patients who required treatment but were determined by their multidisciplinary treatment team, which included at least one vascular surgeon, not to qualify for CEA.
Shortly after the American Heart Association, Giorgio Biasi presented the final results of the ICAROS Study (Imaging in Carotid Angioplasty and Risk of Stroke). The purpose of the study was to see whether it is possible to reduce the neurological complications of carotid stenting by correlating the risk of embolization with the echographic characteristics of the carotid plaque on the basis of a duplex scan.
Over 400 patients from 12 centres were entered into the study and there were neurological complications in 6.6% of patients. Biasi reported that 71.4% of the complications occurred in cases with the duplex scan with a Grey Scale Median assessment (GSM) of less than 25 (very soft echolucent plaque) and embolic particles were collected in only 15% of cases in patients with a GSM of greater than 25.
The conclusion of the ICAROS study was the need to look at the GSM of the plaque as well as the more conventional parameters such as the degree of stenosis or symptoms before deciding to carry out carotid stenting.
