Trainee Experience in Simulation-Based Education of Open Vascular Surgery.

BACKGROUND: Simulation continues to be an important adjunct to vascular surgery training, yet the optimal implementation of simulation to complement conventional surgical training continues to evolve. This study aims to find areas for improvement in current simulation-based training of open vascular skills by characterizing the experience of vascular trainees attending a national simulation-based course. METHOD: This was a survey study conducted at the simulation course of the Annual UCLA/SVS Symposium: A Comprehensive Review and Update of What's New in Vascular and Endovascular Surgery, a national vascular surgery meeting. The survey consisted of 17 questions and was administered on paper or electronically via the Audience Response System, before the start of the course. The survey assessed the participants' experience in formal training, simulation training, and comfort with open surgical procedures. RESULTS: Between 2013 and 2018, the survey was completed by 150 participants of which 65% were vascular fellows. Only 48% of the participants had formal training in suturing and surgical instruments. Most participants had formal training in basic vascular techniques and advanced vascular operations. In 71%, simulation was incorporated into basic technique training and 60% in open surgical training. Simulation training was most commonly utilized in learning anastomotic techniques and open abdominal aortic aneurysm repair. Simulation skills were deemed translatable to the operating room by 59% of participants. Most participants were comfortable performing open vascular procedures. However, 68% of participants were uncomfortable performing an abdominal aortic aneurysm repair. CONCLUSIONS: There continues to be a significant portion of trainees who do not undergo a simulation-based education. Current simulation training is being targeted to meet trainee needs in open vascular surgery, specifically open aneurysm repair. Nonetheless, trainees continue to have doubts regarding applicability of simulation-based skills to the operating theater. Further studies investigating access to simulation education as well as its translatability are needed.

Early Outcomes in the ROADSTER 2 Study of Transcarotid Artery Revascularization in Patients With Significant Carotid Artery Disease.

BACKGROUND AND PURPOSE: Transcarotid artery revascularization (TCAR) is comprised of carotid artery stent placement with cerebral protection via proximal carotid artery clamping and reversal of cerebral arterial flow. The aim of the present study was to evaluate the safety and efficacy of TCAR performed by a broad group of physicians with variable TCAR experience. METHODS: The ROADSTER 2 study is a prospective, open label, single arm, multicenter, postapproval registry for patients undergoing TCAR. Patients considered at high risk for complications from carotid endarterectomy with symptomatic stenosis ≥50% or asymptomatic stenosis ≥80% were included. The primary end point was procedural success, which encompassed technical success plus the absence of stroke, myocardial infarction, or death within the 30-day postoperative period. Secondary end points included technical success and individual/composite rates of stroke, death, and myocardial infarction (MI). All patients underwent independent neurological assessments before the procedure, within 24 hours, and at 30 days after TCAR. An independent clinical events committee adjudicated all major adverse events. RESULTS: Between 2015 and 2019, 692 patients (Intent to Treat Population) were enrolled at 43 sites. Sixty cases had major protocol violations, leaving 632 patients adhering to the Food and Drug Administration-approved protocol (per-protocol population). The majority (81.2%) of operators were TCAR naïve before study initiation. Patients underwent TCAR for neurological symptoms in 26% of cases, and all patients had high-risk factors for carotid endarterectomy (anatomic-related 44%; physiological 32%; both 24%). Technical success occurred in 99.7% of all cases. The primary end point of procedural success rate in the Intent to Treat population was 96.5% (per-protocol 97.9%). The early postoperative outcomes in the Intent to Treat population included stroke in 13 patients (1.9%), death in 3 patients (0.4%), and MI in 6 patients (0.9%). The composite 30-day stroke/death rate was 2.3%, and stroke/death/MI rate was 3.2%. In the per-protocol population, there were strokes in 4 patients (0.6%), death in one patient (0.2%), and MI in 6 patients (0.9%) leading to a composite 30-day stroke/death rate of 0.8% and stroke/death/MI rate of 1.7%. CONCLUSIONS: TCAR results in excellent early outcomes with high technical success combined with low rates of postprocedure stroke and death. These results were achieved by a majority of operators new to this technology at the start of the trial. Adherence to the study protocol and peri-procedural antiplatelet therapy optimizes outcomes. Longer-term follow-up data are needed to confirm these early outcomes. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02536378.

Clinical competence statement of the Society for Vascular Surgery on training and credentialing for transcarotid artery revascularization.

As the practice of medicine grows in complexity, the process of defining the expertise required for the competent execution of specific procedures has also become complex. The Society for Vascular Surgery therefore constituted a task force to provide informed recommendations on the knowledge, technical skills, resources, and infrastructure required to obtain and to maintain privileges for the safe and effective performance of transcarotid artery revascularization (TCAR). The TCAR procedure is being adopted rapidly, and it is therefore important that informed guidance be available expeditiously. Formal training in the pathophysiology and diagnosis of carotid occlusive disease and all management options is essential. Appropriate diagnostic, imaging, endovascular, surgical, and monitoring infrastructure is required, as are resources to maintain quality control. Credentialing and privileging require a combination of both open surgical and endovascular skills. As such, physicians must have hospital privileges to perform carotid endarterectomy. They should attend an appropriate program for education and simulated training in TCAR. In addition, physicians must have performed ≥25 endovascular procedures as the primary operator using low-profile rapid-exchange platforms plus ≥5 TCAR procedures as the primary operator (pathway 1); or they may have acquired ≥25 endovascular procedures as the primary operator using low-profile rapid-exchange platforms and a supplement of 5 TCAR procedures under proctored guidance if they have not performed sufficient TCAR procedures (pathway 2); or a team of two physicians can collaborate, combining the endovascular and surgical requirements plus at least 5 TCAR procedures under proctored guidance (pathway 3).

Endovascular stenting of supra-aortic lesions using a transcarotid retrograde approach and flow reversal: A multicenter case series.

OBJECTIVE: Endovascular treatment has largely replaced open reconstruction of proximal brachiocephalic and left common carotid ostial arterial stenoses. The objective of this study was to report the technical feasibility and safety of a flow-based embolic protection system in stenting of single and tandem stenotic lesions of supra-aortic arch vessels. METHODS: All cases used flow-based neuroprotection by the ENROUTE Transcarotid Neuroprotection System (Silk Road Medical, Sunnyvale, Calif). Case specifics, such as the stents used, the details of flow-based neuroprotection, the order in which lesions were treated, and the case-specific exceptions, are detailed in the body of the publication. The primary end point of this study was the occurrence of stroke or transient ischemic attack. RESULTS: Sixteen patients (12 women) with an average age of 68 years (range, 54-83 years) underwent endovascular stenting to treat single (11 patients) or tandem (5 patients) stenotic lesions of supra-aortic arch vessels. A total of 21 lesions were treated: 7 in the innominate artery, 1 in the right common carotid artery, 8 in the left common carotid artery, and 5 in the internal carotid artery (tandem cases). Eleven patients (69%) were symptomatic, and the stenoses of the five asymptomatic patients were identified during routine workup for comorbidities. Technical success was obtained in all cases. There were no strokes or transient ischemic attacks during the 30 days after the procedure. Minor complications included a minor wound dehiscence that healed secondarily without sequelae and a hematoma at the neck incision that resolved spontaneously without further intervention. CONCLUSIONS: The use of a transcarotid retrograde approach with flow-based neuroprotection is technically feasible for the endovascular stenting of single and tandem stenotic lesions of the supra-aortic arch vessels. These data further support the advantages of a transcarotid approach and flow-based neuroprotection to minimize the risk of intraoperative complications and embolic events during and after the procedure.

Duration of asymptomatic status and outcomes following carotid endarterectomy and carotid artery stenting in the Carotid Revascularization Endarterectomy vs Stenting Trial.

BACKGROUND: Most carotid revascularization studies define asymptomatic as symptom-free for more than 180 days; however, it is unknown if intervention carries similar risk among those currently asymptomatic but with previous symptoms (PS) vs those who were always asymptomatic (AA). METHODS: We compared the periprocedural and 4-year risks of PS vs AA patients in the Carotid Revascularization Endarterectomy vs Stenting Trial (CREST) randomized to carotid endarterectomy (CEA) or carotid artery stenting (CAS)/angioplasty. Proportional hazards models adjusting for age, sex, and treatment were used to assess the risk of periprocedural stroke and/or death (S+D; any S+D during periprocedural period), stroke and death at 4 years (any S+D within the periprocedural period and ipsilateral stroke out to 4 years) and the primary end point at 4 years (any stroke, death, and myocardial infarction within the periprocedural period and ipsilateral stroke out to 4 years). Analysis was performed pooling the CEA-treated and CAS-treated patients, and separately for each treatment. RESULTS: Of 1181 asymptomatic patients randomized in CREST, 1104 (93%) were AA and 77 (7%) were PS. There was no difference in risk when comparing the AA and PS cohorts in the pooled CAS+CEA population for periprocedural S+D (2.0% vs 1.3%), S+D at 4 years (3.6% vs 3.2%), or the primary end point (5.2% vs 5.8%). There were also no differences among those assigned to CEA (periprocedural S+D, 1.5% vs 0%; S+D at 4 years, 2.7% vs 0%; or primary end point, 5.1% vs 2.4%) or CAS (periprocedural S+D, 2.5% vs 2.8%; S+D at 4 years, 4.4% vs 6.9%; or primary end point, 5.3% vs 9.8%) when analyzed separately. CONCLUSIONS: In CREST, only a small minority of asymptomatic patients had previous ipsilateral symptoms. The outcomes of periprocedural S+D, periprocedural S+D, and ipsilateral stroke up to 4 years, and the primary end point did not differ for AA patients compared with PS patients.

Temporary Reversal of Blood Flow During Transcarotid Artery Revascularization Does Not Change Brain Electrical Activity in Lead-In Cases of the ROADSTER 1 Multicenter Trial.

PURPOSE: To evaluate any intraoperative electroencephalographic (EEG) changes accompanying reversed flow with the ENROUTE Transcarotid Neuroprotection System during transcarotid artery revascularization (TCAR). METHODS: A post hoc analysis was performed of the first 81 consecutive lead-in patients (mean age 72.8±8 years; 61 men) enrolled in the ROADSTER 1 trial at 5 participating institutions. All patients had high-grade carotid artery stenosis [53 (59.3%) left sided; 12 (14.8%) contralateral occlusions] and high-risk criteria for carotid endarterectomy. A third had symptoms of either stroke (13, 16.0%) or transient ischemic attack (14, 17.3%). This subset of early patients underwent EEG monitoring to detect any cerebral changes during reversed flow as an added safety measure mandated by the ROADSTER 1 trial protocol. RESULTS: Mean flow reversal time was 12.9±8.2 minutes. The goal mean arterial pressure during reversed flow was 100 mm Hg, but 7 (8.6%) patients suffered hypotension. One (1.2%) patient had slight EEG changes secondary to blood pressure fluctuation; these resolved with blood pressure elevation. No other EEG changes were noted. One (1.2%) patient had a postoperative stroke and another (1.2%) had postoperative myocardial infarction (MI), leading to 2.5% 30-day stroke/death/MI rate. CONCLUSION: Temporary reversal of blood flow during TCAR is a safe maneuver and does not cause cerebral ischemia in the vast majority of patients, including those with contralateral carotid occlusion. Carotid stenting performed with reversed blood flow mitigates cerebral embolization and periprocedural stroke without concern for brain ischemia.

Carotid revascularization and medical management for asymptomatic carotid stenosis: Protocol of the CREST-2 clinical trials.

Rationale Trials conducted decades ago demonstrated that carotid endarterectomy by skilled surgeons reduced stroke risk in asymptomatic patients. Developments in carotid stenting and improvements in medical prevention of stroke caused by atherothrombotic disease challenge understanding of the benefits of revascularization. Aim Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trial (CREST-2) will test whether carotid endarterectomy or carotid stenting plus contemporary intensive medical therapy is superior to intensive medical therapy alone in the primary prevention of stroke in patients with high-grade asymptomatic carotid stenosis. Methods and design CREST-2 is two multicenter randomized trials of revascularization plus intensive medical therapy versus intensive medical therapy alone. One trial randomizes patients to carotid endarterectomy plus intensive medical therapy versus intensive medical therapy alone; the other, to carotid stenting plus intensive medical therapy versus intensive medical therapy alone. The risk factor targets of centrally directed intensive medical therapy are LDL cholesterol <70 mg/dl and systolic blood pressure <140 mmHg. Study outcomes The primary outcome is the composite of stroke and death within 44 days following randomization and stroke ipsilateral to the target vessel thereafter, up to four years. Change in cognition and differences in major and minor stroke are secondary outcomes. Sample size Enrollment of 1240 patients in each trial provides 85% power to detect a treatment difference if the event rate in the intensive medical therapy alone arm is 4.8% higher or 2.8% lower than an anticipated 3.6% rate in the revascularization arm. Discussion Management of asymptomatic carotid stenosis requires contemporary randomized trials to address whether carotid endarterectomy or carotid stenting plus intensive medical therapy is superior in preventing stroke beyond intensive medical therapy alone. Whether carotid endarterectomy or carotid stenting has favorable effects on cognition will also be tested. Trial registration United States National Institutes of Health Clinicaltrials.gov NCT02089217.

Direct Cervical Carotid Angioplasty with Flow Reversal: A Single-Center Report from the Roadster Trial.

BACKGROUND: Carotid stent and/or angioplasty (CAS) via the transfemoral route with distal protection carries twice the risk of stroke and/or death when compared with carotid endarterectomy (CEA) in multiple randomized trials. Potential causes for this include disadvantaged aortic arch anatomy and the need to traverse the lesion to place a distal protection device. This report describes the technique and our experience with direct CAS using flow reversal for embolic protection. METHODS: University of California at Los Angeles (UCLA) division of Vascular and Endovascular surgery was a participant in the multi-institutional Roadster Trial of high-risk patients. We are reporting on our experience with 8 patients who met high-risk criteria. Using a small supraclavicular cutdown, the Michi sheath from Silk Road Medical was inserted into the common carotid artery. This provides a working channel for internal CAS as well as a side port to reverse and divert blood flow to the femoral vein, for embolic protection. All patients qualified as medically high risk because of a combination of factors including advanced age, smoking history, hypertension, diabetes, coronary artery disease, or hostile neck anatomy. RESULTS: All 8 patients had 3 or more risk factors including age >75 years (6 of 8), smoking (6 of 8), hypertension (7 of 8), overt coronary artery disease (4 of 8), diabetes (2 of 8), and chronic obstructive pulmonary disease (1 of 8). All stenoses were in the 80-99% category, and all were asymptomatic. All patients tolerated temporary clamping with flow reversal with no electroencephalogram changes. There were no deaths, strokes, transient ischemic attacks, or myocardial infarctions. All patients were discharged on the first postoperative day. Follow-up ranged from 7 to 21 months. One patient developed in-stent restenosis (asymptomatic). CONCLUSIONS: Direct CAS with flow reversal appears to be a safe, less invasive alternative to CEA.

Recognition and Surgical Techniques for Management of Nonrecurrent Laryngeal Nerve during Carotid Endarterectomy.

The presence of a nonrecurrent laryngeal nerve (NRLN) during carotid endarterectomy (CEA) may significantly limit the exposure of the surgical field during this operation. Although its reported incidence is rare, NRLN typically overlies the carotid bifurcation and failure to recognize this anatomic variation increases the risk of NRLN injury. A retrospective chart review of all patients who underwent CEA for hemodynamically significant extracranial carotid stenosis between January 2005 and December 2014 was performed. All patients with NRLN encountered intraoperatively were identified. Clinical outcomes, surgical techniques, and complications were reviewed and reported. Four left-sided NRLN were identified and 4 were right sided. No cranial nerve deficits or injuries occurred after CEA in patients where NRLN was encountered. Two distinct surgical techniques were used to manage patients with NRLN and they are discussed in detail.

Long-Term Results of Stenting versus Endarterectomy for Carotid-Artery Stenosis.

BACKGROUND: In the Carotid Revascularization Endarterectomy versus Stenting Trial, we found no significant difference between the stenting group and the endarterectomy group with respect to the primary composite end point of stroke, myocardial infarction, or death during the periprocedural period or any subsequent ipsilateral stroke during 4 years of follow-up. We now extend the results to 10 years. METHODS: Among patients with carotid-artery stenosis who had been randomly assigned to stenting or endarterectomy, we evaluated outcomes every 6 months for up to 10 years at 117 centers. In addition to assessing the primary composite end point, we assessed the primary end point for the long-term extension study, which was ipsilateral stroke after the periprocedural period. RESULTS: Among 2502 patients, there was no significant difference in the rate of the primary composite end point between the stenting group (11.8%; 95% confidence interval [CI], 9.1 to 14.8) and the endarterectomy group (9.9%; 95% CI, 7.9 to 12.2) over 10 years of follow-up (hazard ratio, 1.10; 95% CI, 0.83 to 1.44). With respect to the primary long-term end point, postprocedural ipsilateral stroke over the 10-year follow-up occurred in 6.9% (95% CI, 4.4 to 9.7) of the patients in the stenting group and in 5.6% (95% CI, 3.7 to 7.6) of those in the endarterectomy group; the rates did not differ significantly between the groups (hazard ratio, 0.99; 95% CI, 0.64 to 1.52). No significant between-group differences with respect to either end point were detected when symptomatic patients and asymptomatic patients were analyzed separately. CONCLUSIONS: Over 10 years of follow-up, we did not find a significant difference between patients who underwent stenting and those who underwent endarterectomy with respect to the risk of periprocedural stroke, myocardial infarction, or death and subsequent ipsilateral stroke. The rate of postprocedural ipsilateral stroke also did not differ between groups. (Funded by the National Institutes of Health and Abbott Vascular Solutions; CREST ClinicalTrials.gov number, NCT00004732.).

Carotid angiographic characteristics in the CREST trial were major contributors to periprocedural stroke and death differences between carotid artery stenting and carotid endarterectomy.

OBJECTIVE: The Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) demonstrated a higher periprocedural stroke and death (S+D) rate among patients randomized to carotid artery stenting (CAS) than to carotid endarterectomy (CEA). Herein, we seek factors that affect the CAS-CEA treatment differences and potentially to identify a subgroup of patients for whom CAS and CEA have equivalent periprocedural S+D risk. METHODS: Patient and arterial characteristics were assessed as effect modifiers of the CAS-CEA treatment difference in 2502 patients by the addition of factor-by-treatment interaction terms to a logistic regression model. RESULTS: Lesion length and lesions that were contiguous or were sequential and noncontiguous extending remote from the bulb were identified as influencing the CAS-to-CEA S+D treatment difference. For those with longer lesion length (≥12.85 mm), the risk of CAS was higher than that of CEA (odds ratio [OR], 3.42; 95% confidence interval [CI], 1.19-9.78). Among patients with sequential or remote lesions extending beyond the bulb, the risk for S+D was higher for CAS relative to CEA (OR, 9.01; 95% CI, 1.20-67.8). For the 37% of patients with lesions that were both short and contiguous, the odds of S+D in those treated with CAS was nonsignificantly 28% lower than for CEA (OR, 0.72; 95% CI, 0.21-2.46). CONCLUSIONS: The higher S+D risk for those treated with CAS appears to be largely isolated to those with longer lesion length and/or those with sequential and remote lesions. In the absence of those lesion characteristics, CAS appears to be as safe as CEA with regard to periprocedural risk of S+D.

Issues to Be Addressed and Hopefully Resolved in the Carotid Revascularization Endarterectomy Versus Stenting Trial 2.

The superiority of carotid endarterectomy (CEA) plus best medical treatment (BMT) over BMT alone for the management of patients with asymptomatic carotid stenosis is based on randomized controlled trials that recruited patients up to 30 years ago. Best medical treatment has improved considerably since that time with respect to stroke prevention. Furthermore, a new carotid intervention has emerged during the last 2 decades and has gradually become established, that is, carotid artery stenting (CAS). Consequently, the efficacy of current BMT alone needs to be compared not only with CEA plus BMT but also with CAS plus BMT to determine which strategy achieves the optimal stroke prevention rates. This article highlights the purpose of the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) 2 and discusses the issues that CREST-2 will hopefully provide answers to.

Temporal Changes in Periprocedural Events in the Carotid Revascularization Endarterectomy Versus Stenting Trial.

BACKGROUND AND PURPOSE: Post-hoc, we hypothesized that over the recruitment period of the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST), increasing experience and improved patient selection with carotid stenting, and to a lesser extent, carotid endarterectomy would contribute to lower periprocedural event rates. METHODS: Three study periods with approximately the same number of patients were defined to span recruitment. Composite and individual rates of periprocedural stroke, myocardial infarction, and death rate were calculated separately by treatment assignment (carotid stenting/carotid endarterectomy). Temporal changes in unadjusted event rates, and rates after adjustment for temporal changes in patient characteristics, were assessed. RESULTS: For patients randomized to carotid stenting, there was no significant temporal change in the unadjusted composite rates that declined from 6.2% in the first period, to 4.9% in the second, and 4.6% in the third (P=0.28). Adjustment for patient characteristics attenuated the rates to 6.0%, 5.9%, and 5.6% (P=0.85). For carotid endarterectomy-randomized patients, both the composite and the combined stroke and death outcome decreased between periods 1 and 2 and then increased in period 3. CONCLUSIONS: The hypothesized temporal reduction of stroke+death events for carotid stenting-treated patients was not observed. Further adjustment for changes in patient characteristics between periods, including the addition of asymptomatic patients and a >50% decrease in proportion of octogenarians enrolled, resulted in practically identical rates. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00004732.

Effect of patching on reducing restenosis in the carotid revascularization endarterectomy versus stenting trial.

BACKGROUND AND PURPOSE: The purpose is to determine whether patching during carotid endarterectomy (CEA) affects the perioperative and long-term risks of restenosis, stroke, death, and myocardial infarction as compared with primary closure. METHODS: We identified all patients who were randomized and underwent CEA in Carotid Revascularization Endarterectomy versus Stenting Trial. CEA patients who received a patch were compared with patients who underwent CEA with primary closure without a patch. We compared periprocedural and 4-year event rates, 2-year restenosis rates, and rates of reoperation between the 2 groups. We further analyzed results by surgeon specialty. RESULTS: There were 1151 patients who underwent CEA (753 [65%] with patch and 329 [29%] with primary closure). We excluded 44 patients who underwent eversion CEA and 25 patients missing CEA data (5%). Patch use differed by surgeon specialty: 89% of vascular surgeons, 6% of neurosurgeons, and 76% of thoracic surgeons patched. Comparing patients who received a patch versus those who did not, there was a significant reduction in the 2-year risk of restenosis, and this persisted after adjustment by surgeon specialty (hazard ratio, 0.35; 95% confidence interval, 0.16-0.74; P=0.006). There were no significant differences in the rates of periprocedural stroke and death (hazard ratio, 1.58; 95% confidence interval, 0.33-7.58; P=0.57), in immediate reoperation (hazard ratio, 0.6; 95% confidence interval, 0.16-2.27; P=0.45), or in the 4-year risk of ipsilateral stroke (hazard ratio, 1.23; 95% confidence interval, 0.42-3.63; P=0.71). CONCLUSIONS: Patch closure in CEA is associated with reduction in restenosis although it is not associated with improved clinical outcomes. Thus, more widespread use of patching should be considered to improve long-term durability. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00004732.

Guidelines for the primary prevention of stroke: a statement for healthcare professionals from the American Heart Association/American Stroke Association.

The aim of this updated statement is to provide comprehensive and timely evidence-based recommendations on the prevention of stroke among individuals who have not previously experienced a stroke or transient ischemic attack. Evidence-based recommendations are included for the control of risk factors, interventional approaches to atherosclerotic disease of the cervicocephalic circulation, and antithrombotic treatments for preventing thrombotic and thromboembolic stroke. Further recommendations are provided for genetic and pharmacogenetic testing and for the prevention of stroke in a variety of other specific circumstances, including sickle cell disease and patent foramen ovale.

Agreement between site-reported and ultrasound core laboratory results for duplex ultrasound velocity measurements in the Carotid Revascularization Endarterectomy versus Stenting Trial.

OBJECTIVE: Patients in the Carotid Revascularization Endarterectomy vs Stenting Trial (CREST) had duplex ultrasound (DU) scans prior to treatment and during follow-up to document the severity of carotid disease and the anatomic outcome of carotid endarterectomy (CEA) or carotid artery stenting (CAS). An ultrasound core laboratory (UCL) reviewed DU data from the clinical sites. This analysis was done to determine the agreement between site-reported and UCL-verified DU velocity measurements. METHODS: Clinical site DU worksheets, B-mode images, and Doppler velocity waveforms for the treated carotid arteries were reviewed at the UCL. The highest internal carotid artery peak systolic velocity (PSV) and associated Doppler angle were verified. If the angle was misaligned by >3 degrees, it was remeasured at the UCL and the PSV was recalculated. Agreement for PSV was defined as site-reported PSV within ± 5% of UCL-verified PSV. Transcription errors were corrected by the UCL but were not considered as disagreements. Follow-up analysis was limited to patients who received the assigned treatment. RESULTS: The UCL reviewed 1702 prior-to-treatment and 1743 12-month follow-up DU scans (873 CEA, 870 CAS) from 111 clinical sites. Site-reported and UCL-verified PSV agreed in 1124 (66%) of the prior-to-treatment scans and 1200 (69%) of the follow-up scans. In those cases with a disagreement, Doppler angle accounted for disagreement in 339 (59%) of the prior-to-treatment scans and 277 (51%) of the follow-up scans. Based on a threshold PSV for ≥ 70% stenosis of ≥ 230 cm/s on the prior-to-treatment scans and ≥ 300 cm/s on the follow-up scans, UCL review resulted in reclassification of stenosis severity in 75 (4.4%) of the prior-to-treatment scans and 13 (0.75%) of the follow-up scans. There is evidence that the proportion of reclassification at follow-up was greater for CAS (10 scans; 1.2%) than for CEA (three scans; 0.34%) (P = .057). CONCLUSIONS: There was a high rate of agreement between site-reported and UCL-verified DU results in CREST, and UCL review was associated with a low rate of stenosis reclassification. However, angle alignment errors were quite common and prompted recalculation of velocity in 20% of prior-to-treatment scans and 18% of follow-up scans. The use of a UCL provides a uniform process for DU interpretation and can identify sources of error and suggest technical improvements for future studies.