Perioperative Complications After Carotid Artery Stenting: A Contemporary Experience From the University at Buffalo Neuroendovascular Surgery Team
Dumont, Travis M. MD*,‡; Wach, Michael M. BS‡; Mokin, Maxim MD, PhD*,‡; Sorkin, Grant C. MD*,‡; Snyder, Kenneth V. MD, PhD*,‡,§,‖; Hopkins, L. Nelson MD*,‡,§,‖,¶; Levy, Elad I. MD*,‡,§; Siddiqui, Adnan H. MD, PhD*,‡,§
*Department of Neurosurgery and Toshiba Stroke and Vascular Research Center, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York;
‡Department of Neurosurgery, Gates Vascular Institute, Kaleida Health, Buffalo, New York;
§Department of Radiology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York;
‖Department of Neurology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York;
¶Jacobs Institute, Buffalo, New York
Correspondence: Adnan H. Siddiqui, MD, PhD, University at Buffalo Neurosurgery, 100 High St, Suite B4, Buffalo New York 14203. E-mail: firstname.lastname@example.org
Received January 10, 2013
Accepted June 27, 2013
BACKGROUND: Technological advances have resulted in diminishing perioperative complications reported during carotid artery stenting (CAS) trials. Because trial experience lags behind technological advances, an understanding of the incidence of perioperative complications after CAS remains in flux.
OBJECTIVE: In this single-arm, observational study, a contemporary experience of CAS at a high-volume academic training center for neuroendovascular surgeons was reviewed to assess perioperative morbidity.
METHODS: A prospectively maintained database of all neuroendovascular procedures was queried for all CAS procedures performed for stenotic atherosclerotic disease between 2009 and 2011. Each case was assessed for major perioperative (30 day) adverse events, including new acute ischemic stroke, postoperative symptomatic intracranial hemorrhage, myocardial infarction (MI), and mortality.
RESULTS: A total of 474 patients were identified. Perioperative adverse events were noted in 13 patients (2.7%). These included 4 ischemic strokes, 4 intracranial hemorrhages, 3 MIs, and 5 deaths. Most perioperative events occurred in symptomatic patients (10 of 239 symptomatic patients with events, 4.2% event incidence), whereas these events occurred rarely in asymptomatic patients (3 of 235 asymptomatic patients with events, 1.3% event incidence).
CONCLUSION: In this retrospective analysis of consecutive patients treated with CAS, the perioperative incidence of stroke (0.9%), MI (0.6%), and death (1.1%) was favorable.
ABBREVIATIONS: CAS, carotid artery stenting
CEA, carotid endarterectomy
CREST, Carotid Revascularization Endarterectomy versus Stenting Trial
MI, myocardial infarction
NASCET, North American Symptomatic Carotid Endarterectomy Trial
NIHSS, National Institutes of Health Stroke scale
The use of carotid artery stenting (CAS) has increased since its inception.1 Recent trials have suggested that the perioperative morbidity of CAS is similar to that of carotid endarterectomy (CEA).2 Technological advances have resulted in diminished perioperative complications reported in CAS trials.3-6 The authors wish to share a contemporary experience of CAS at an academic training center for neuroendovascular surgeons to provide an understanding of procedure-related nuances and perioperative risk at a high-volume center. We compare this experience with that reported some years ago to highlight advances in technology and the effects of cumulative experience.
PATIENTS AND METHODS
Study Design, Setting, Population
After receiving approval from the University at Buffalo institutional review board, our prospectively maintained database of all neuroendovascular procedures was queried for all CAS procedures performed for stenotic atherosclerotic disease between January 2009 and December 2011. Because the intended focus of this retrospective review is on atherosclerotic disease, patients with complete occlusion of the extracranial internal carotid artery before the stenting procedure (n = 21) and patients with carotid dissection as an indication for stenting (n = 14) were excluded from the present analysis and have been reported separately.7,8
Each case was assessed for major perioperative (30 day) adverse events, including new acute ischemic stroke, postoperative symptomatic intracranial hemorrhage, myocardial infarction (MI), and mortality. Acute ischemic stroke was defined as any new, symptomatic thromboembolic event confirmed with radiographic imaging (for the purpose of this retrospective review, the official report from the attending radiologist was used to assess findings consistent with cerebral infarction) that resulted in permanent neurological deficit associated with an increase in the preoperative National Institutes of Health Stroke scale (NIHSS) score of at least 1 point for >24 hours. Postoperative symptomatic intracranial hemorrhage was defined as any intracranial hemorrhage not related to trauma in the distribution of the treated carotid artery that worsened the NIHSS score by at least 1 point, confirmed by radiographic imaging. For MI, the Universal Definition of Myocardial Infarction9 was applied. Perioperative mortality was defined as death occurring within 30 days of the CAS procedure.
Preoperative case details were reviewed, including symptomatology, demographic data (age and sex), concomitants of carotid artery stenosis (hypertension, hypercholesterolemia, diabetes mellitus, and history of cigarette smoking), neurological examination (NIHSS score), and anatomic lesion characteristics of plaque ulceration and degree of stenosis. Stenosis was separated into 10-degree intervals of severity, measured by North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria10 as 50% to 59%, 60% to 69%, 70% to 79%, 80% to 89%, and 90% to 99%.
At our center, carotid stenting procedures are performed with the patient under conscious sedation and with the use of biplane fluoroscopy. Embolic protection was used in all cases performed during the study period. Difficult cases are frequently discussed preoperatively at a multidisciplinary neurovascular conference where treatment plans (including CAS vs CEA vs medical therapy, method of embolic protection, and specific stent device) are determined. Pre-stent angioplasty is rarely performed and, when done, is limited to cases in which the stenosis is so severe that the nondeployed stent may not be readily passed through the lesion without undue force. Post-stenting angioplasty is generally performed with an angioplasty balloon sized to the diameter of the nondiseased internal carotid artery for asymptomatic patients and undersized (by 0.5-1.0 mm) to the nondiseased internal carotid artery for symptomatic patients in an effort to limit plaque emboli. In cases where intraluminal thrombus after stenting is suspected, we test stent architecture postangioplasty to confirm no plaque extrusion by using intravascular ultrasound imaging. We perform aspiration from the internal carotid artery in all cases of proximal protection and selectively in cases of distal protection.
Postoperative care for all patients includes telemetry, with frequent (every 1-2 hours) neurological assessments. Postoperative laboratory testing includes cardiac enzyme analysis (creatinine kinase, creatinine kinase-MB, troponin I) obtained initially 0 to 4 hours postoperatively, followed by at least 2 additional assessments in 8-hour intervals. An electrocardiogram is performed postoperatively and compared with a preoperative study. Carotid Doppler ultrasonography ipsilateral to the stent is performed to assess for improvement in flow velocity in comparison with the preoperative study. Additional diagnostic study is performed on a case-by-case basis as required. Follow-up is arranged approximately 30 days postoperatively for neurological assessment and screening Doppler ultrasonography of the treated vessel. Further follow-up is determined on a case-by-case basis, but, in general, we recommend that patients return for follow-up at 3 and 6 months with Doppler ultrasonography and annual screening thereafter.
For this study, perioperative complications are reported as a percentage for the entire cohort, and further dichotomized for symptomatic and asymptomatic patients. Basic statistical analysis was performed with GraphPad Prism (version 6.0; GraphPad Software, San Diego, California).
Descriptive and Outcome Data
A total of 480 cases of carotid revascularization were planned. In 6 cases, planned CAS procedures were aborted for the following reasons: no acceptable femoral or radial artery access (2 cases), nonnavigable aortic arch (3 cases), and inability to cross the internal carotid artery lesion with a microwire (1 case). These cases are not included in the present analysis. Clinical characteristics for the 474 analyzed cases are summarized in Table 1. By a small margin, most patients were symptomatic (239 [50.4%], vs 235 [49.6%] asymptomatic). Perioperative complications were noted in 2.7% of patients (n = 13) and included 4 ischemic strokes (0.9%), 4 intracranial hemorrhages (0.9%), 3 MIs (0.6%), and 5 deaths (1.1%). Most perioperative events occurred in symptomatic patients (10 patients with events, 4.2% event incidence in symptomatic patients), whereas these events in asymptomatic patients were rare (3 patients with events, 1.3% event incidence). The incidence of perioperative events was significantly greater in symptomatic patients than in asymptomatic patients (P = 0.047, Fisher exact). Perioperative events are summarized in Table 2. Transient ischemic attacks were noted in 5 patients, including 3 in symptomatic and 2 in asymptomatic patients.
One ischemic stroke in a patient with symptomatic carotid stenosis resulted in major morbidity, the other 3 strokes caused an increase of <4 NIHSS points. All intracranial hemorrhages were symptomatic and resulted in morbidity (including neurological deficit) and prolonged hospitalization. Perioperative MIs were generally mild, but all resulted in prolongation of hospitalization. In 1 patient with asymptomatic carotid stenosis, complications related to a perioperative MI resulted in the patient's death. Case details for the 5 patients who did not survive 30 days after CAS are summarized in Table 3.
Proximal embolic protection was used in 48 cases, including 36 symptomatic and 12 asymptomatic patients. No perioperative stroke, MI, or death occurred in this subset of patients; however, 1 of 5 Transient ischemic attacks and 2 of 4 intracranial hemorrhages for the entire series occurred in this subset of patients. The incidence of perioperative intracranial hemorrhage with use of proximal embolic protection (4.2%) was more frequent but not significantly different than that for patients treated with distal embolic protection (0.5% incidence of intracranial hemorrhage); P = 0.0528, Fisher exact. Use of proximal embolic protection became more frequent during this series (2009: 5 cases, 4% of case volume; 2010: 9 cases, 6% of case volume; 2012: 34 cases, 18% of case volume). Intravascular ultrasonography was used in 72 cases, although its use changed the management in only 1 case, which has been previously reported.11
Key Results and Interpretation
In our experience, perioperative risk of major adverse events was low (2.7%). The importance of the frequency of and familiarity with CAS procedures at our facility cannot be minimized. Most patients were enrolled in ongoing trials and were treated with carotid stenting owing to anatomic or physiological high-risk criteria for CEA. Embolic protection was used in all cases. Carotid stenting was performed in all patients by surgeons trained to perform both CEA and CAS. It is interesting that the perioperative complication rate in this cohort was less than that reported from the same center in an earlier report.12 This decrease in morbidity is coincident with increasing experience, an ongoing evolution of technology, and consistent with trial data and nationwide data sampling.1
The rate of perioperative stroke, MI, or death (2.1% total; 4.2% for symptomatic patients; 1.3% for asymptomatic patients) was lower than that noted in the most recent large randomized trial for carotid revascularization (in the Carotid Revascularization Endarterectomy vs Stenting Trial [CREST],2 6.7% and 5.4% risk of stroke, death, or MI after CAS and CEA for symptomatic patients, respectively; and 3.5% and 3.6% risk of stroke, death, or MI after CAS and CEA for asymptomatic patients, respectively). Additionally, the rates of stroke or death in our series of 3.0% for symptomatic patients and 0.9% for asymptomatic patients were lower than reported in CREST for CAS (symptomatic 6.0%, asymptomatic 2.5%) and historical CEA trials for symptomatic patients (5.8% in NASCET10) and asymptomatic patients (2.3% in Asymptomatic Carotid Atherosclerosis Study13) and comparable to the CREST CEA cohort (symptomatic CEA 3.2%; and asymptomatic CEA 1.4%).
The trend toward an increased incidence of symptomatic intracranial hemorrhage in patients treated with proximal embolic protection in our series is difficult to explain. This may be related to intraoperative hypoperfusion when the common carotid artery is occluded with balloon inflation or subsequent luxury perfusion after the balloon is deflated, but it is most likely attributed to chance. This finding may merit further study, although the incidence of cerebral hemorrhage in prospective registries with proximal embolic protection was low (0%14–0.8%15). That no periprocedural ischemic stroke occurred with proximal embolic protection is the primary reason for its increasing use throughout this series.
These results reflect outcomes following CAS in a large patient cohort treated at a high-volume center by surgeons experienced in both CEA and CAS. Surgeons at lower-volume centers may experience a higher rate of complications.16 The experience presented here suggests that perioperative risk may be stratified based on the patient's symptomatology. More importantly, we have detailed the procedural nuances that have been incorporated into our CAS repertoire over the years and reflect the improved outcomes noted in this large series compared with previous data. These prominently include the use of proximal protection for symptomatic cases, limited angioplasty pre-stenting, use of intravascular ultrasound, and aggressive aspiration at the end of the procedure.
We are increasingly using proximal embolic protection strategies with flow arrest or flow reversal in symptomatic patients. In addition, we tend to use a closed-cell stent design for symptomatic patients and are less aggressive with post-stent balloon angioplasty, routinely undersizing the balloon by up to 1 mm from the distal nominal internal carotid artery diameter. In patients with suspected coronary artery disease, we are similarly underinflating the carotid artery post-stenting to avoid rebound hypotension, which is the principal trigger for post-stenting MI. The use of intravascular ultrasound to assess for intraluminal thrombus has not yielded a high rate of findings that have changed management; however, it may play a role in the diagnosis of intraluminal thrombus after stenting as a low-risk and high-reward supplementary safeguard in protection against thromboembolism.11,17
Our death rate of 1.1%, although comparable to reported results (CAS 0.7%, CEA 0.3% in CREST2), is high because of our early intervention (within 7 days of symptomatic event) in patients with major ischemic strokes (NIHSS 7-11). We have adopted this strategy because there is significant evidence that earlier intervention is more protective for recurrent events.18 Although we did not increase the ischemic burden post-CAS, 3 of 5 deaths were in patients who did not significantly improve and died of complications related to the presenting event.
As is well recognized, our experience is consistent with perioperative risk stratified on the basis of the patient's symptomatology. We expect the decline in CAS-related perioperative complications to continue as proximal protection strategies, particularly for symptomatic and high-embolic-risk asymptomatic patients, become more prevalent. Judicious use of post-stent angioplasty is critical in preventing periprocedural MIs and embolic release from plaque. We hope that this experience and the strategies discussed will be of assistance to surgeons during planning for interventions for carotid artery disease that require revascularization procedures.
This case series is limited by its retrospective nature and self-reporting of complications. The combination of these limitations may cause an underreporting of the incidence of perioperative complications, because patients experiencing complications after discharge may present to another treatment facility or may be lost to follow-up. Furthermore, stroke-free survival beyond the perioperative 30-day window would be valuable information for comparison with trial data, but is beyond the scope of this retrospective project.
In this retrospective analysis of consecutive patients treated with CAS, the perioperative incidence of stroke (0.9%), MI (0.6%), and death (1.1%) was favorable.
Drs Dumont and Sorkin and Michael M. Wach report no financial relationships. Dr Hopkins receives grant/research support from Toshiba; serves as a consultant to Abbott, Boston Scientific, Cordis, Micrus, and Silk Road; holds financial interests in AccessClosure, Augmenix, Boston Scientific, Claret Medical, Endomation, Micrus, and Valor Medical; holds a board/trustee/officer position with Access Closure and Claret Medical; serves on Abbott Vascular's speakers' bureau; and has received honoraria from Bard, Boston Scientific, Cleveland Clinic, Complete Conference Management, Cordis, Memorial Health Care System, and the Society for Cardiovascular Angiography and Interventions (SCAI). Dr Levy receives research grant support (principal investigator: Stent-Assisted Recanalization in acute Ischemic Stroke, SARIS), other research support (devices), and honoraria from Boston Scientific and research support from Codman & Shurtleff, Inc and ev3/Covidien Vascular Therapies; has ownership interests in Intratech Medical Ltd. and Mynx/Access Closure; serves as a consultant on the board of Scientific Advisors to Codman & Shurtleff, Inc; serves as a consultant per project and/or per hour for Codman & Shurtleff, Inc, ev3/Covidien Vascular Therapies, and TheraSyn Sensors, Inc; and receives fees for carotid stent training from Abbott Vascular and ev3/Covidien Vascular Therapies. Dr Levy receives no consulting salary arrangements. All consulting is per project and/or per hour. Dr Mokin has received an educational grant from Toshiba Medical System Corporation. Dr Siddiqui has received research grants from the National Institutes of Health (co-investigator: NINDS 1R01NS064592-01A1, Hemodynamic induction of pathologic remodeling leading to intracranial aneurysms) and the University at Buffalo (Research Development Award) (neither grant is related to the present work); holds financial interests in Hotspur, Intratech Medical, StimSox, Valor Medical and Blockade Medical; serves as a consultant to Codman & Shurtleff, Inc, Concentric Medical, Covidien Vascular Therapies, GuidePoint Global Consulting, Penumbra, Inc, Stryker Neurovascular and Pulsar Vascular; belongs to the speakers' bureaus of Codman & Shurtleff, Inc and Genentech; serves on National Steering Committees for Penumbra, Inc 3D Separator Trial and Covidien SWIFT PRIME Trial; serves on an advisory board for Codman & Shurtleff and Covidien Vascular Therapies; and has received honoraria from American Association of Neurological Surgeons' courses, Annual Peripheral Angioplasty and All That Jazz Course, Penumbra, Inc, and from Abbott Vascular and Codman & Shurtleff, Inc for training other neurointerventionists in carotid stenting and for training physicians in endovascular stenting for aneurysms. Dr Siddiqui receives no consulting salary arrangements. All consulting is per project and/or per hour. Dr Snyder serves as a consultant to, a member of the speakers' bureau, and has received honoraria from Toshiba. He serves as a member of the speakers' bureau for and has received honoraria from ev3/Covidien Vascular Therapies and The Stroke Group (consultants to the healthcare industry, Littleton, CO). (Boston Scientific's neurovascular business has been acquired by Stryker.)
The authors thank Debra J. Zimmer for editorial assistance.
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The authors provide a single center retrospective review of the outcomes of 474 patients undergoing carotid artery stenting over the span of 2 years from 2009 to 2011. They treated nearly an even amount of symptomatic (50.4%) and asymptomatic (49.6%) patients. They found an overall complication rate of 2.7% including ischemic stroke (0.9%), intracranial hemorrhage (0.9%), myocardial infarction (0.6%), and death (1.1%). There was a significant difference between the overall complication rates between symptomatic (4.2%) vs asymptomatic (1.3%) patients. The authors reported that these complication rates are lower compared to the most recent randomized controlled trial, the CREST study. During the course of the study there was an increasing use of proximal embolic protection devices and intravascular ultrasound. There was a statistically non-significant trend towards increased rate of intracranial hemorrhage, and decreased rate of stroke/TIA with the use of a proximal protection device. While the overall complication rates were lower compared to the CREST trial, the mortality rates were slightly higher, which the authors attribute to their protocol of early intervention (within 7 days) after initial major ischemic stroke (NIHSS 7-11). If that is the case they might reconsider this protocol especially in patients with disabling or large strokes. While several studies do show the benefit of early revascularization in symptomatic lesions, this is only shown in patients with small of non-disabling stroke. AHA guidelines for acute stroke reflect that revascularization within days of a large or disabling is high risk.1 However it is unlikely that this alone can attribute to the higher mortality rates seen because 2 out of the 5 mortalities were from the asymptomatic group. While there continues to be technological and procedural advances in the field of carotid stenting which reduces the associated risk of morbidity & mortality, our medical treatments also continue to improve. A concerning point to this review is the amount of asymptomatic patients treated when recent studies suggest maximal medical therapy may be equitable to any intervention. At this point what is needed is another randomized trial comparing maximal medical therapy, carotid artery stenting with embolic protection devices, and carotid endarterectomy in order to see if the recent advances in medical therapy and stenting have been able to improve the outcomes to the point that justifies changing the standard of care.
Johanna T. Fifi
New York, New York
1. Jauch EC, Saver JL, Adams HP, et al.. Guidelines for the early management of patients with acute ischemic stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2013;44(3):870–947. View Full Text | PubMed | CrossRef Cited Here... |
The authors present a single center retrospective analysis of 474 patients treated with carotid artery stenting (CAS) between 2009 and 2011. Two hundred and thirty nine patients were symptomatic, 235 patients were asymptomatic. Patients with carotid artery dissection or chronic occlusions were excluded. The overall major adverse event rate including ICH during the 30 day perioperative procedure rate was 2.7%. The breakdown for the overall major adverse event (MAE) rate including ICH was 4.2% for symptomatic patients and 1.3% for asymptomatic patients respectively. Even though the authors do not present long term data and the study design is limited by its retrospective nature, the data suggest further improvement of the CAS procedure in comparison to the perioperative CREST data. In CREST, the 30 day MAE rate was 6.7% for symptomatic patients and 3.5% for asymptomatic patients treated with CAS. The authors suggest that improved technique with strict application of embolic protection for every case, either proximal or distal, as well as better patient selection in a multidisciplinary consensus conference are key factors in improving outcomes. I congratulate the authors to their good results and review. I believe the article is timely, as criticism and skepticism towards carotid stenting, particularly in asymptomatic patients, persists among our colleagues in the post CREST era.
Marvin Darkwah Oppong
In patients with carotid stenosis, what is the approximate 4-year rate of serious adverse events (stroke, myocardial infarction, death) undergoing carotid artery stenting or carotid endarterectomy?
What is the main factor that makes stroke centers that treat a high volume of patients with carotid stenting or endarterectomy have better outcome than low volume centers?
A) Increased operator experience
B) Reduced ambulance travel time
C) Increased community education
D) Better availability of IV thrombolytics
E) Reduced rate of patient comorbidities
According to the American Heart Association, patients with symptomatic carotid stenosis should undergo carotid revascularization (CAS or CEA) if noninvasive imaging demonstrates narrowing of the ipsilateral internal carotid artery by at least what percent?
Carotid stenosis; Carotid stenting; Complications
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