Rationale and status of randomized controlled clinical trials in carotid artery stenting

National trends in carotid artery revascularization surgery

Object

Several randomized trials have emerged with conflicting data on the overall safety of carotid artery stenting (CAS) in comparison with carotid endarterectomy (CEA). The authors hypothesize that changes in national trends correspond to publication of randomized trials, including an increase in utilization of CAS after publication of trials favorable to CAS (for example, Carotid and Vertebral Artery Transluminal Angioplasty Study [CAVATAS] and Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy [SAPPHIRE]) and decrease in utilization of CAS after publication of trials favorable to CEA (for example, Endarterectomy versus Stenting in Patients with Symptomatic Severe Carotid Stenosis [EVA3-S] and Stent-Supported Percutaneous Angioplasty of the Carotid Artery versus Endarterectomy [SPACE]).

Methods

The Nationwide Inpatient Sample was obtained for the years 1998–2008. Individual cases were isolated for principal diagnosis of unilateral or bilateral carotid artery stenosis or occlusion undergoing CEA or CAS. The percentage of CAS for all carotid revascularization procedures was calculated for each year. Perioperative inpatient morbidity, including stroke or death, were calculated and compared.

Results

The percentage of patients undergoing CAS increased yearly from the start of the observed period to the end, with the exception of a decrease in 2007. The peak utilization of CAS for carotid artery revascularization procedures was 15% of all cases in 2006. The stroke or death rate was consistent at 5% among all patients undergoing CEA for all years, while the incidence of stroke or death decreased among patients undergoing CAS from 9% in 1998 to 5% in 2008.

Conclusions

The practice of CAS in the US is expanding, from less than 3% of all carotid artery revascularization procedures to 13% in 2008. The utilization of CAS was seen to correlate with publication of randomized trials. Utilization nearly doubled in 2005 after publication of the CAS-favorable SAPPHIRE in 2004, and decreased by 22% after publication of the CEA-favorable EVA-3S and SPACE in 2007. With the publication of Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST), the authors predict a resultant increase in the rate of CAS for carotid artery disease in the upcoming years.

[CT diagnostics of carotid artery stenosis]

CT angiography can be used to evaluate carotid artery stenosis with high diagnostic safety. In contrast to the gold standard digital subtraction angiography (DSA) it is a non-invasive procedure which yields information regarding the degree of stenosis as well as information about plaque morphology. Due to multiple reconstruction planes in 3 levels in maximum intensity projections (MIP) and the possibility to perform volume rendering (VR) reconstruction more information about the extent of carotid disease can be acquired. Due to the bolus tracking technique optimum contrast medium enhancement of the carotid artery with simultaneous minimization of venous artifacts is possible.

Percutaneous transluminal angioplasty for atherosclerotic stenoses of intracranial vessels

SUMMARY

To study the efficacy and long-term outcome of percutaneous transluminal angioplasty (PTA) with/without stent placement for intracranial atherosclerotic stenoses, we reviewed our treated cases retrospectively. Between May 1992 and October 2003, PTA with/without stents was performed in 64 intracranial and skull base vessels in 62 patients, including 24 middle cerebral arteries, 16 internal carotid arteries, 13 vertebral arteries, and 11 basilar arteries. PTA was technically successful in 55 vessels (86%). However, four vessels (6%) failed to achieve satisfactory dilatation. We encountered five periprocedural strokes as symptomatic complications, for a mortality rate of 4.7% and a morbidity rate of 3.1%. All the patients with stent placements survived angioplasty without any complication. In the clinical follow-up available for one week to 11.5 years (mean, 4.7 years), there were three strokes related to the treated vessels. The annual stroke rate in the affected territory was estimated at 1.2% per year. According to these results, PTA for intracranial atherosclerotic stenoses seems to be a beneficial therapy for immediate anatomical results and long-term stroke prevention. Stent-assisted PTA could help patients achieve successful dilatation and avoid complications.

Training for Carotid Intervention: Preparing the Next Generation

BACKGROUND

Carotid interventions are performed to reduce the cumulative risk of stroke. The success of the procedure is dependent upon maintaining low operative risk. This article reviews the current state of training for both carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAS).

METHODS

Medline searches were performed to identify articles with the combination of the following key words: carotid, endarterectomy, stent, training, assessment and simulation. Manual searches of the reference lists and related papers was conducted.

RESULTS

Training and assessment for CEA and CAS follows the traditional apprenticeship model. There is no formal training protocol or objective means of assessment for either carotid endarterectomy or stenting. Models and simulators to allow for training and assessment away from the operative theatre have been developed, and exist for both CEA and CAS.

CONCLUSION

The technology exists to allow for both training and assessment of competency to take place in a controlled and objective environment for both CEA and CAS. The use of simulation needs to be robustly evaluated and assessed to both complement and augment existing training programs to ensure that the highest standards of care are maintained for treatment of carotid territory disease. Objective competency based training and assessment is no longer unattainable. Simulators augment this process and without them operative exposure is sporadic and crisis management infrequent.

Patient selection for carotid stenting versus endarterectomy: A systematic review

Carotid artery stenting has emerged as an alternative to carotid endarterectomy for the treatment of severe extracranial carotid stenosis in patients with anatomic or clinical factors that increase their risk of complications with surgery, yet there remains a substantial amount of variability and uncertainty in clinical practice in the referral of patients for stenting vs endarterectomy. By undertaking a thorough review of the literature, we sought to better define which subsets of patients with "high-risk" features would be likely to preferentially benefit from carotid stenting or carotid endarterectomy. Although only a single randomized trial comparing the outcomes of carotid stenting with distal protection and endarterectomy has been completed, a wealth of observational data was reviewed. Relative to endarterectomy, the results of carotid stenting seem favorable in the setting of several anatomic conditions that render surgery technically difficult, such as restenosis after prior endarterectomy, prior radical neck surgery, and previous radiation therapy involving the neck. The results of stenting are also favorable among patients with severe concomitant cardiac disease. Carotid endarterectomy, alternatively, seems to represent the procedure of choice among patients 80 years of age or older in the absence of other high-risk features. Overall, existing data support the concept that carotid stenting and endarterectomy represent complementary rather than competing modes of therapy. Pending the availability of randomized trial data to help guide procedural selection, which is likely many years away, an objective understanding of existing data is valuable to help select the optimal mode of revascularization therapy for patients with severe carotid artery disease who are at heightened surgical risk.

Cerebral protection devices for use during carotid artery angioplasty with stenting: A health technology assessment

Objectives:This study sought to examine the safety, efficacy, and economic implications of the use of cerebral protection devices during carotid artery angioplasty and stenting (CAS) in high-risk patients with severe carotid artery disease (CAD).

Methods:A comprehensive search for peer- and non–peer-reviewed studies that compared carotid endarterectomy (CEA) or CAS without cerebral protection to CAS with cerebral protection and appeared in the English language literature between January 1990 and January 2005 was completed. Information from studies identified was extracted using a common data abstraction form and then critically appraised against published quality assessment criteria.

Results:Of the eight studies found, six provided information on technical or procedural success rates, with values ranging from 95.6 percent to 100 percent. Three of the four studies comparing groups of patients who received CAS with cerebral protection with those who received only CAS reported a non-statistically significantly higher 30-day incidence of death and stroke (major or minor) in the latter group. None of the three studies comparing CAS with cerebral protection to CEA demonstrated a statistically significant difference in the 30-day incidence of death, major stroke, or myocardial infarction between treatment groups. No economic analyses were found.

Conclusions:In high-risk patients with severe CAD, the evidence suggests that CAS with cerebral protection may offer a safe and efficacious alternative to CEA, reducing the risk of embolic peri-procedural complications associated with CAS to acceptable levels.

Rapid measurement of S-100B serum protein levels by Elecsys S100 immunoassay in patients undergoing carotid artery stenting or endarterectomy

OBJECTIVES

This study was designed to apply the rapid Elecsys S100 immunoassay for real-time measurement of S100 protein serum levels indicating acute brain damage in patients undergoing carotid artery stenting (CAS) or endarterectomy (CEA).

DESIGN AND METHODS

Data of 14 CAS patients were compared to those of 43 CEA and 14 control patients undergoing coronary angiography (CA). S100 serum levels were measured by the full-automatic Elecsys S100 immunoassay and compared to those obtained by the well-established LIA-mat S100 system.

RESULTS

In contrast to CAS and CA patients, median S100 serum levels of CEA patients significantly increased to 0.24 ng/mL before declamping, but subsequently returned to baseline. Three CEA patients with neurological deficits showed sustained elevated S100 levels 6 h after extubation. Absolute S100 values were not significantly different between the two methods. Bland-Altman plot analyses displayed a good agreement, mostly indicating slightly smaller values applying the Elecsys S100 system.

CONCLUSIONS

The Elecsys S100 system appears to be suitable for rapid real-time detection of neurological deficits in patients undergoing CAS and CEA. Persistent elevations of Elecsys S100 levels during CEA were associated with prolonged neurological disorders, whereas transient increases seem to represent impaired blood-brain barrier integrity without neurological deficits.

Feasibility Trial of Carotid Stenting With and Without an Embolus Protection Device

PURPOSE

To evaluate the feasibility of stenting and cerebral protection in patients with carotid bifurcation disease.

METHODS

Carotid stenting with self-expanding nitinol stents was evaluated in 261 patients (157 men; mean age 70.9+/-9.7 years, range 41-90) treated at 33 clinical sites. Among these patients, 141 (54.3%) were symptomatic, and 71 (27.2%) had postendarterectomy restenotic lesions. An embolus protection device became available in the latter third of the study. The primary endpoint of the study was the 30-day composite occurrence of major adverse clinical events (all deaths, strokes, or myocardial infarctions [MI]). At 1 year, the endpoint included all deaths, strokes, or MIs at 30 days, plus all deaths or ipsilateral strokes between 31 days and 1 year.

RESULTS

SMART stents were placed in 147 (56%) patients and Precise stents in 107 (41%); 7 (3%) patients were treated with non-study stents. Lesion success, defined as <30% postprocedural residual stenosis, was achieved in 249 (95%). An AngioGuard filter was used in 85 patients; of 90 filters employed, 78 (87%) were successfully deployed and retrieved. Visible material was noted in 42 (54%) retrieved filters. One (0.4%) stent thrombosis occurred at <30 days, and no restenotic lesions >80% were noted in up to 1 year of follow-up. At 30 days, stroke occurred in 16 (6.1%) patients, MI in 1 (0.4%), and 2 (0.8%) patients died. The 30-day rate of stroke, MI, or death was 6.9%. Major ipsilateral stroke occurred in 4 (1.5%) patients between 0 and 30 days; no new major ipsilateral strokes were noted up to 1 year. By Kaplan-Meier analysis, the 1-year risk of stroke, MI, or death was 10.9%+/-2.0%. The 1-year risk of major ipsilateral stroke was significantly lower in patients treated with embolus protection devices (0.0% versus 2.3%, p=0.05).

CONCLUSIONS

The use of nitinol self-expanding stents in the carotid position appears to be a safe and efficacious alternative for the treatment of carotid bifurcation disease. The addition of embolus protection devices may diminish the risk of postprocedural major ipsilateral strokes.

Transcervical Approach With Protective Flow Reversal for Carotid Angioplasty and Stenting

PURPOSE

To report our initial experience using a transcervical approach for carotid angioplasty/stenting (CAS) that employs internal carotid artery (ICA) flow reversal for neuroprotection.

METHODS

Seventeen patients (15 men; mean age 65 years, range 49-77) with significant carotid stenosis (mean 88%, 8 symptomatic) were treated with protected transcervical CAS. Eleven patients were considered at high risk for carotid endarterectomy; 8 were also considered high risk for transfemoral access (unfavorable aortic arch anatomy or advanced aortoiliac occlusive disease). Anesthesia was based on patient and anesthesiologist preferences. The approach consisted of a 2-cm cutdown over the common carotid artery and placement of a 9-F sheath. ICA flow was reversed and shunted into the jugular vein during the carotid intervention.

RESULTS

Access and carotid stenting were successful in all cases. Thirteen procedures were performed under general and 4 under local anesthesia. Mean flow reversal time was 34+/-4 minutes (25 minutes in the last 7 cases). The patients tolerated the procedure well and had no neurological events. Four (23%) patients had significant oozing from the operative site; 2 developed small neck hematomas that were treated conservatively. All patients were discharged on the first postoperative day. There were no deaths, changes in neurological status, or restenosis over a mean follow-up of 12 months (range 1-24).

CONCLUSIONS

Our initial experience demonstrates that a transcervical approach is a viable alternative for CAS. The procedure can be performed safely, with good initial clinical outcomes. The approach allows carotid flow reversal and emboli protection without introducing neuroprotection devices. The method appears best suited for patients at high risk for endarterectomy and transfemoral access.

The Role of Carotid Endarterectomy in the Endovascular Era

OBJECTIVE

Carotid artery angioplasty and stenting (CAS) has been proposed as an alternative to surgery for patients with high-grade symptomatic carotid disease. The purpose of this study was to determine the proportion of patients that were suitable for each type of intervention and to analyse the reasons that precluded stenting.

MATERIALS AND METHODS

This was a prospective observational study. All patients considered for intervention for carotid artery disease during an 18-month period were analysed. The management decision was recorded, as were the reasons for unsuitability for stenting.

RESULTS

Two hundred and sixty-eight patients' data were analysed, 224 had complete records. Forty-seven patients did not require intervention and received best medical treatment alone. One hundred and seventy-seven patients required intervention, 113 were suitable for stenting and 64 were not. In 51 patients stenting was preferred. Sixty-two patients were suitable for either stent or surgery. Sixty-four patients were unsuitable for stenting. Carotid tortuosity and proximal disease accounted for 70% of this group.

CONCLUSIONS

Current enthusiasm for carotid stenting might well be supported by the results of ongoing randomised-controlled clinical trials. However, this study highlights a significant proportion (64/177; 36%) of our patients is presently unsuitable for stenting. The common technical difficulties and limitations of stenting encountered in our unit are related predominantly to carotid anatomy.

[Diagnostic evaluation of carotid artery stenoses with multislice CT angiography. Review of the literature and results of a pilot study]

BACKGROUND

The accurate evaluation of carotid artery stenoses is important for therapeutic decision making. Catheter digital subtraction angiography (DSA) still represents the gold standard, while the advent of multislice CT (MSCT) has led to improved temporal and spatial resolutions of CTA.

MATERIAL AND METHODS

In a pilot study, we investigated 14 diseased vessels in 9 symptomatic patients (7m, 2f; mean age 60.7+/-10,9 years) comparing biplanar DSA with standardized 16-slice MS-CTA. The degree of stenosis was evaluated in a consensus reading following modified NASCET criteria.

RESULTS

DSA demonstrated 4 occlusions, 5 high-grade stenoses (>70%) and 5 lower-grade stenoses (<70%). One dissecting, infrapetrous stenosis was not adequately quantified by CTA due to a close topographic relation to the skull base. In the carotid bifurcation (n=13), an excellent correlation was demonstrated between DSA and CTA with a correlation coefficient of 0.99.

CONCLUSION

MS-CTA has a good diagnostic potential in the evaluation of carotid artery stenoses. Larger studies will need to demonstrate the relative diagnostic value for different subtypes of stenosis and for different reader experience levels.

Technical challenges in a program of carotid artery stenting

OBJECTIVES

Successful carotid artery stenting (CAS) involves gaining access to the common carotid artery, characterizing and crossing the lesion, deploying an anti-embolic device and stent, and retrieving the anti-embolic device. These steps are critical determinants of the complexity of the procedure. The frequency with which technical challenges are encountered during CAS is ill-defined. The purpose of this investigation was to review the incidence and types of technical challenges encountered during CAS and determine their effect on outcome.

METHODS

Data were prospectively collected for 194 consecutive CAS procedures (177 patients) and separated into group 1, standard CAS technique, and group 2, procedures with technical challenges requiring modifications to the technique. Technical challenges were defined as difficult femoral arterial access (aortoiliac occlusive disease), complex aortic arch anatomy (elongated or bovine arch, deep takeoff of the innominate artery, tandem stenoses (CCA, innominate artery), difficult internal carotid artery anatomy (tortuosity, high-grade stenosis), and circumferential internal carotid artery calcification. The incidence of technical challenges, types of technical modifications required, and effect on outcomes were determined.

RESULTS

Fifty technically challenging situations (26%) were encountered in 194 CAS procedures (group 2), which required advanced technical skills. Standard methods were used in the other 144 procedures (group 1, 74%). No significant differences in 30-day stroke and death rates were noted between the groups (group 1, 3.1%; group 2, 2.0%; P = .564).

CONCLUSIONS

Twenty-six percent of the procedures required a modification in the standard technique for successful CAS. Circumferential calcification and severe tortuosity continue to be relative contraindications to CAS. Recognition of these technical challenges and increasing facility with the methods to manage them will enable expanded use of CAS without increased morbidity and mortality.