Sriram S. Iyer

Elective Stenting of the Extracranial Carotid Arteries

OBJECTIVES In symptomatic and asymptomatic patients with significant carotid artery stenosis, surgical endarterectomy has been shown to be beneficial when compared with medical management. Carotid stenting is evolving as an alternative technique for treating such patients. This prospective study was designed to assess the feasibility and safety of carotid angioplasty and stenting. METHODS Fourteen patients (15 carotid arteries) with significant carotid artery stenosis were enrolled. These patients were in the age range 46 to 84 years (mean 60.9 +/- 7 years) and there were 12 males (86%). All of these patients were symptomatic with either TIA (n = 8) or stroke (n = 6). Wallstents were used in all the cases to stent the carotid arteries. One patient underwent bilateral carotid artery stenting. RESULTS Carotid angioplasty and stenting was successful in 13 out of 14 (92.8%) patients and 14 out of 15 (93.3%) carotid arteries, with reduction in mean (+/- SD) stenosis from 86 +/- 6% to 3 +/- 3%. There was one episode of minor stroke, no major stroke or death during the initial hospitalization. Another patient had a minor stroke with patent ipsilateral carotid artery (on repeat angiography) during the first 30 days after the procedure. This patient was also found to have asymptomatic thrombus formation in the contralateral carotid stent which resolved with intravenous anticoagulation. During a mean follow up of 6 +/- 2 months there has been no recurrence of symptoms. CONCLUSIONS Based upon our limited experience we believe that percutaneous carotid angioplasty with stenting is feasible with low periprocedural complication rate.

Immediate and Late Clinical Outcomes of Carotid Artery Stenting in Patients With Symptomatic and Asymptomatic Carotid Artery Stenosis

Background—Carotid stenting is a less invasive percutaneous procedure than carotid endarterectomy for the treatment of carotid stenosis. Reports suggest that it can be performed with periprocedural complication rates similar to those of carotid endarterectomy. The purpose of this study was to determine short- and long-term outcomes in the largest prospective cohort of carotid stenting patients. Methods and Results—This study followed 528 consecutive patients (604 hemispheres/arteries) undergoing carotid stenting. There was a 0.6% (n=3) fatal stroke rate and 1% (n=5) nonstroke death rate at 30 days. The major stroke rate was 1% (n=6), and the minor stroke rate was 4.8% (n=29). The overall 30-day stroke and death rate was 7.4% (n=43). Over the 5-year study period, the 30-day minor stroke rate improved from 7.1% (n=7) for the first year to 3.1% (n=5) for the fifth year (P<0.05 for trend). The best predictor of 30-day stroke and death was age ≥80 years. After the 30-day period, the incidence of fatal and nonf...

Effectiveness of Clopidogrel and Aspirin Versus Ticlopidine and Aspirin in Preventing Stent Thrombosis After Coronary Stent Implantation

BACKGROUND Ticlopidine has been shown to reduce the incidence of stent thrombosis compared with warfarin, but it may cause serious hematological side effects. Clopidogrel, a new thienopyridine derivative, may be a safe alternative to ticlopidine. The aim of this study was to compare the safety and efficacy of clopidogrel and aspirin with those of ticlopidine and aspirin in patients undergoing coronary stent implantation. METHODS AND RESULTS The population of this study consisted of 2 groups: patients who underwent coronary stenting and were treated with ticlopidine and aspirin (TA group, n=1406), and patients who underwent coronary stenting followed by treatment with clopidogrel and aspirin (CA group, n=283). At 1-month follow-up, there was no difference in stent thrombosis (1.5% versus 1.4%, P=1.0) or major adverse cardiac events (3.1% versus 2.4%, P=0. 85) between the TA and CA groups, respectively. The probability of any side effect (neutropenia, diarrhea, rash) was significantly higher in the TA group (10.6% versus 5.3%, P=0.006; relative risk, 0. 53; CI, 0.32 to 0.86). CONCLUSIONS These data suggest that clopidogrel may be an effective pharmacological regimen after coronary stent implantation. Furthermore, the simpler dosing regimen, the absence of neutropenia, and the lower frequency of other side effects make it a safe alternative to ticlopidine.

Predictors of Stroke Complicating Carotid Artery Stenting

BACKGROUND The evolving technique of carotid stenting is being evaluated as an alternative to endarterectomy. Identification of the factors that predispose a patient to neurological complications would facilitate further refinement of the technique and optimize patient selection. METHODS AND RESULTS We analyzed the impact of various clinical, morphological, and procedural determinants on the development of procedural strokes in 231 patients who underwent elective (primary) stenting of 271 extracranial carotid arteries. The mean age of the patients was 68.7+/-10 years, 165 (71%) were males, and 139 (60%) had symptoms attributed to the lesion treated. This series represented a high-risk subset with 164 patients (71%) having significant coronary artery disease, 91 (39%) having bilateral disease, and 28 (12%) having contralateral carotid occlusion. Of the treated vessels, 59 (22%) had prior carotid endarterectomy, 66 (24%) had ulcerated plaques, and 87 (32%) had calcified lesions. Only 37 treated vessels (14%) would have been eligible for inclusion in the North American Symptomatic Carotid Endarterectomy Trial (NASCET). There were 17 (6.2%) minor and 2 (0.7%) major strokes during and within 30 days of the procedure. NASCET-eligible patients had a low (2.7%) risk of procedural strokes after carotid stenting. The results of multivariate analysis revealed advanced age (P=.006) and presence of long or multiple stenoses (P=.006) as independent predictors of procedural strokes. CONCLUSIONS During this procedural developmental phase of carotid stenting, neurological complications were highly dependent on patient selection. Advanced age and long or multiple stenoses were independent predictors of procedural stroke.

Carotid stenting with distal protection in high surgical risk patients: the BEACH trial 30 day results.

Background: The BEACH trial evaluated the outcomes of carotid artery stent placement with distal emboli protection, using the Carotid Wallstent® and the FilterWire EX®/EZTM, in patients at high surgical risk for carotid endarterectomy (CEA). Methods: We enrolled 747 patients at high surgical risk for CEA due to prespecified anatomical criteria and/or medical comorbidities. The trial included both symptomatic (>50% carotid artery stenosis) as well as asymptomatic (>80% carotid artery stenosis) high surgical risk patients. Three groups of patients were included in the trial. The Roll‐in (R) group (n = 189/747, [25%]) included up to nine patients per site for familiarization of the device and protocol; the Pivotal (P) group (n = 480/747, [65%]) was intended for presentation to the FDA for consideration of device approval; and a Bilateral (B) registry group (n = 78/747, [10%]) was included because of the need to treat patients with bilateral carotid artery disease. In the 480 Pivotal patients, anatomic criteria represented the most frequent high‐risk surgical category for enrollment (58.8%), followed by prior CEA (34.2%), multivessel (≥2) coronary artery disease (21.7%), and contralateral carotid occlusion (18.1%). Results: The technical success rate for stent deployment and FilterWire EX/EZ deployment and retrieval was 98.2%. The mean postprocedure angiographic diameter stenosis in the Pivotal group was reduced to 10.8%, while the overall procedure success rate (<50% residual diameter stenosis) after stent deployment was 98%. The 30 day composite major adverse event (MAE) rate for the entire cohort of 747 patients (i.e. inclusive of all 3 groups) was 5.8% (all death = 1.5%, all stroke = 4.4%, and all myocardial infarction (MI) = 1.0%). In subgroup analysis, there was no significant difference in the MAE rate between the three groups (P = 5.8%, R = 6.9%, B = 2.6%, P = 0.42). Conclusion: The similarity in periprocedural event rates for the Pivotal and Roll‐in groups suggests a flat learning curve for experienced operators using this carotid stent system. The similarity in event rates for the Bilateral group, when compared with the Roll‐in and Pivotal groups, suggests that staged sequential treatment of bilateral stenoses may be performed at the same risk as for unilateral lesions. The 30‐day safety of this stent and distal emboli protection system is encouraging and compares favorably with other carotid stent trials in high surgical risk patients.

Angioplasty and Stenting for Restenosis After Carotid Endarterectomy Initial Experience

BACKGROUND AND PURPOSE Endarterectomy for recurrent carotid stenosis after endarterectomy has a significantly higher complication rate than the original operation. Angioplasty and stenting may offer a useful alternative treatment for these patients. METHODS Between September 1994 and April 1996, 22 patients had 25 carotid arteries treated with angioplasty and stenting for postendarterectomy restenosis. All patients had an independent neurological examination and National Institutes of Health Stroke Scale evaluation before and after the procedure. Patients were treated with aspirin and ticlopidine. All patients were requested to return at 6 months for follow-up angiography. The mean patient age was 69 +/- 7 years, and the mean elapsed time from endarterectomy was 73 +/- 69 months. Seventy-seven percent of the patients were symptomatic. RESULTS Mean stenosis was reduced from 79 +/- 13% before the procedure to 1.8 +/- 3.6% after stenting. One patient had a minor stroke, for a complication rate of 4% per treated artery. In the eight patients who returned for 6-month angiography, mean stenosis was 19.4 +/- 4.4% and restenosis (> or = 50% stenosis) did not occur. CONCLUSIONS In a small series, angioplasty and stenting appear to be safe and well tolerated for the treatment of postendarterectomy restenosis.

Multicenter evaluation of carotid artery stenting with a filter protection system

OBJECTIVES The aim of this study was to evaluate the feasibility and safety of carotid artery stenting (CAS) with a filter protection system. BACKGROUND Neurologic events linked to the embolization of particulate matter to the cerebral circulation may complicate CAS. Strategies designed to capture embolic particles during carotid intervention are being evaluated for their efficacy in reducing the risk of these events. METHODS Between September 1999 and July 2001, a total of 162 patients (164 hemispheres) underwent CAS with filter protection (NeuroShield, MedNova Ltd., Galway, Ireland) according to prospective protocols evaluating the filter system at three institutions. RESULTS Angiographic success was achieved in 162 of the procedures (99%) and filter placement was successful in 154 (94%) procedures. Carotid access was unsuccessful in two cases (1%) and filter placement in eight cases (5%). Of the latter, five procedures were completed with no protection and three were completed using alternative protection devices. On an intention-to-treat basis, the overall combined 30-day rate of all-stroke and death was 2% (four events: two minor strokes and two deaths). This includes one minor stroke in a patient with failed filter placement and CAS completed without protection. There was one cardiac arrhythmic death and one death from hyperperfusion-related intracerebral hemorrhage. There were no major embolic strokes. CONCLUSIONS Carotid artery stenting with filter protection is technically feasible and safe. Early clinical outcomes appear to be favorable and need to be confirmed in a larger comparative study.

Efficacy of a filter device in the prevention of embolic events during carotid angioplasty and stenting: An ex vivo analysis

OBJECTIVE Although percutaneous angioplasty and stenting (PTAS) of carotid bifurcation lesions is feasible and appropriate for surgically inaccessible lesions, its general role and comparative value remain unclarified. Moreover, the acceptance of carotid PTAS has been limited by its potential for producing embolic debris. This study used an ex vivo model to evaluate the efficacy of a novel filter device to entrap emboli during PTAS of human carotid plaques. METHODS Eight carotid bifurcation plaques were obtained from patients who underwent carotid endarterectomy for high-grade atherosclerotic stenosis (>90%). The mean age of the patients was 63 years, and six patients were symptomatic. Each plaque was encased with polytetrafluoroethylene material to simulate adventitia and was connected to a perfusion circuit, which provided continuous flow through the plaque. The filter device consisted of an expandable polymeric membrane with multiple micro pores that was attached to the distal end of a 0.014-in wire with a shapeable tip. This filter was encased in a delivery catheter. With fluoroscopic guidance, the filter wire was passed through the stenosis and the delivery catheter was then retracted to open the filter to capture particles released into the distal internal carotid artery. PTAS with a self-expandable stent then was carried out over the filter wire. The particles released during the initial filter passage, those captured in the filter, and those that flowed through or around the filter (missed) were collected and analyzed with light microscopy. RESULTS Filter deployment, PTAS, and filter retrieval were achieved successfully with each lesion. Because the filter has a low crossing profile, it passed through the stenoses smoothly and only produced occasional small particles. PTAS improved the angiographic stenosis from 96.2% +/- 3.7% to 1.3% +/- 1.6%. The mean number and the maximum size of the particles that were released during initial filter passage, missed, and captured by the filter device were 3.1 and 500 microm, 2.8 and 360 microm, 20.1 and 1100 microm, respectively. Most of the particles and those of large size were released during PTAS. The filter captured 88% of these particles. CONCLUSION These study results show that this filter device, at least in this model, did not add complexity to the interventional procedure itself. Furthermore, the filter may markedly decrease embolic events during carotid PTAS and expand the indications for this procedure.

Realizing the Potential of Carotid Artery Stenting Proposed Paradigms for Patient Selection and Procedural Technique

Carotid artery stenting, compared with carotid endarterectomy, is emerging as an effective and less invasive method of revascularization for extracranial carotid artery stenosis. Carotid stenting is established as the treatment of choice for certain high-risk patient subsets, and ongoing clinical trials are evaluating this method across a broader clinical spectrum, including asymptomatic patients. For carotid stenting to reach its full potential, an acceptable risk of periprocedural complications, particularly in low-risk patients, must be ensured (the “3% rule”). The present article provides an in-depth review of carotid stenting, with special emphasis on the process of risk stratification pertaining to clinical, anatomic, and procedural considerations necessary to optimize procedural safety and patient outcomes.

Safety, efficacy, and durability of carotid artery stenting for restenosis following carotid endarterectomy: a multicenter study.

Purpose: To present the results of a multicenter registry established to collect data on carotid stent procedures in patients with restenosis following carotid endarterectomy. Methods: The procedural details, outcomes, and late follow-up results were collected from 14 centers in the United States. Thirty-day and late stroke and death rates were analyzed. Results: Three hundred and thirty-eight patients (201 men; 71 ± 8 years) underwent carotid stenting in 358 arteries. The average duration from carotid endarterectomy was 5.5 ± 7.3 years. Sixty-one percent of the patients were asymptomatic. The overall 30-day stroke and death rate was 3.7%. The minor stroke rate was 1.7% (6/358), and the major nonfatal stroke rate was 0.8% (3/358). The fatal stroke rate was 0.3% (1/358), and the nonstroke-related death rate was 0.9% (3/338). There was 1 (0.3%) fatal and 1 (0.3%) nonfatal stroke during the follow-up period. The overall 3-year rate of freedom from all fatal and nonfatal strokes was 96% ± 1% (±SE). Conclusions: Carotid artery stenting can be performed in patients with restenosis following carotid endarterectomy with 30-day complication rates comparable to those of most published studies on repeat carotid endarterectomy. Results of late follow-up suggest that this technique is durable and efficacious.