Influence of multiple stents on periprocedural stroke after carotid artery stenting in the Carotid Revascularization Endarterectomy versus Stent Trial (CREST)

BACKGROUND

In the Carotid Revascularization Endarterectomy versus Stent Trial (CREST), carotid artery atherosclerotic lesion length and nature of the lesions were important factors that predicted the observed difference in stroke rates between carotid endarterectomy and carotid artery stenting (CAS). Additional patient-related factors influencing CAS outcomes in CREST included age and symptomatic status. The importance of the operator's proficiency and its influence on periprocedural complications have not been well defined. We evaluated data from CREST to determine the impact of use of multiple stents, which we speculate may be related to technical proficiency.

METHODS

CREST includes CAS performed for symptomatic ≥50% carotid stenosis and asymptomatic ≥70% stenosis. Both symptomatic and asymptomatic patients were enrolled in the trial and in the lead-in registry. Data from patients enrolled in the CREST registry and randomized trial from 2000 to 2008 were reviewed for patient- and lesion-related characteristics along with number of stents deployed. The occurrence of 30-day stroke and demographic and clinical features were recorded. Odds ratios for 30-day stroke associated with the use of multiple stents were calculated in univariate analysis and on multivariable analysis after adjustment for demographics (age, sex, symptomatic status), lesion characteristics (length, ulceration, eccentric, percentage stenosis), and risk factors (diabetes, hypertension, dyslipidemia, and smoking).

RESULTS

The registry (n = 1531) and trial (n = 1121) enrolled 2652 patients undergoing CAS. The mean age was 69 years; 36% were women, and 38% were symptomatic. The mean diameter stenosis was 78%, and the mean lesion length was 18 mm (±standard deviation, 8 mm). Risk factors included hypertension (85%), diabetes (32%), dyslipidemia (84%), and smoking (23%). All patients received Acculink stents (Abbott Vascular, Abbott Park, Ill) that were 20, 30, or 40 mm in length (straight or tapered) and Accunet (Abbot Vascular) embolic protection when possible. Most patients received one stent (n = 2545), whereas 98 patients received two stents and 9 patients received three stents (P < .001) to treat the lesion. Patients receiving more than one stent were older (P = .01) but did not differ in other demographic or risk factors. Strokes occurred in 118 (4.5%) of all CAS procedures, in 102 (4%) with the use of one stent, and in 16 (15%) with the use of two or three stents. After adjustment for demographics, lesion characteristics, and risk factors, the use of more than one stent resulted in 2.90 odds (95% confidence interval, 1.49-5.64) for a stroke.

CONCLUSIONS

Although we know that lesion characteristics (length, ulceration) play an important role in CAS outcomes, in this early experience with carotid stenting, a significant and independent relationship existed between the number of stents used and procedural risk of CAS. We postulate that this was an indicator of the operator's inexperience with the procedure.

Periprocedural Stroke and Myocardial Infarction as Risks for Long-Term Mortality in CREST

BACKGROUND

The Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) previously reported increased mortality in patients who sustained a periprocedural stroke or cardiac event (myocardial infarction [MI] or biomarker only) in follow-up to 4 years. We now extend these observations to 10 years.

METHODS AND RESULTS

CREST is a randomized controlled trial designed to compare the outcomes of carotid stenting versus carotid endarterectomy. Proportional hazards models were used to assess the association between mortality and periprocedural stroke, MI, or biomarker-only events. For 10-year follow-up, patients with periprocedural stroke were at 1.74× the risk of death compared with those without stroke (adjusted hazard ratio [HR]=1.74; 95% CI, 1.21-2.50; P<0.003). This increased risk was driven by increased early (between 0 and 90 days) mortality (adjusted HR=14.41; 95% CI, 5.33-38.94; P<0.0001), with no significant increase in late (between 91 days and 10 years) mortality (adjusted HR=1.40; 95% CI, 0.93-2.10; P=0.11). Patients with a protocol MI were at 3.61× increased risk of death compared with those without MI (adjusted HR=3.61; 95% CI, 2.28-5.73; P<0.0001), with an increased hazard both early (adjusted HR=8.20; 95% CI, 1.86-36.2; P=0.006) and late (adjusted HR=3.40; 95% CI, 2.09-5.53; P<0.0001). Patients with a biomarker-only event were at 2.04× increased risk overall (adjusted HR=2.04; 95% CI, 1.09-3.84; P=0.03) than those without MI, with an increased early hazard (adjusted HR=8.44; 95% CI, 1.09-65.5; P=0.04) and a suggestive but nonsignificant association toward higher 91-day to 10-year risk (1.88; 95% CI, 0.97-3.64; P=0.062) contributing to the increased risk.

CONCLUSIONS

In the CREST trial, patients with periprocedural events demonstrate a substantial increase in future mortality to 10 years. For stroke, this risk is largely confined to an early time frame while periprocedural MI or biomarker-only events confer a continuous increased mortality for 10 years. Strategies to reduce periprocedural events and to optimize the evaluation and management of patients with cardiac events should be considered in efforts to reduce not only early but also long-term mortality.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov . Unique identifier: NCT00004732.

Carotid revascularization and medical management for asymptomatic carotid stenosis - Hemodynamics (CREST-H): Study design and rationale

RATIONALE

For patients with asymptomatic high-grade carotid stenosis, clinical investigations have focused on preventing cerebral infarction, yet stenosis that reduces cerebral blood flow may independently impair cognition. Whether revascularization of a hemodynamically significant carotid stenosis can alter the course of cognitive decline has never been investigated in the context of a randomized clinical trial.

HYPOTHESIS

Among patients randomized in the Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis (CREST-2) trials, the magnitude of treatment differences (revascularization versus medical management alone) with regard to cognition will differ between those with flow impairment compared to those without flow impairment.

SAMPLE SIZE

We will enroll approximately 500 patients from CREST-2, of which we anticipate 100 will have hemodynamic impairment. We estimate 93% power to detect a clinically meaningful treatment difference of 0.5 SD.

METHODS AND DESIGN

We will use perfusion-weighted magnetic resonance imaging to stratify by hemodynamic status. Linear regression will compare treatment differences, controlling for baseline cognitive status, age, depression, prior cerebral infarcts, silent infarction, white matter hyperintensity volume, and cerebral microbleeds.

STUDY OUTCOMES

The primary outcome is change in cognition at one year. Secondary outcomes include silent infarction, change in white matter hyperintensity volume, number of cerebral microbleeds, and cortical thickness over one year.

DISCUSSION

If cognitive impairment can be shown to be reversible by revascularization, then we can redefine "symptomatic carotid stenosis" to include cognitive impairment and identify a new population of patients likely to benefit from revascularization.

TRIAL REGISTRATION

US National Institutes of Health (NIH) clinicaltrials.gov NCT03121209.

Pathophysiology of venous ulceration

Our understanding of the pathophysiologic process of venous ulceration has dramatically increased during the past two decades because of dedicated, venous-specific basic science research. Currently, the mechanisms regulating venous ulceration are a combination of macroscopic and microscopic pathologic processes. Macroscopic alterations refer to pathologic processes related to varicose vein formation, vein wall architecture, and cellular abnormalities that impair venous function. These processes are primarily caused by genetic factors that lead to the destruction of normal vein wall architecture and venous hypertension. Venous hypertension causes a chronic inflammatory response that over time can cause venous ulceration. The inciting inflammatory injury is chronic extravasation of macromolecules and red blood cell degradation products and iron overload. Chronic inflammation causes white blood cell extravasation into the dermis with secretion of numerous proinflammatory cytokines. These cytokines transform the phenotype of fibroblasts to a contractile phenotype that increases tension in the dermis. In addition, iron overload keeps macrophages in an M1 phenotype, which leads to tissue destruction instead of dermal repair. Current surgical and medical therapies are primarily directed at eliminating venous hypertension and promoting venous ulcer wound healing. Despite advances in our understanding of venous ulcer formation and healing, ulcers still take an average of 6 months to heal, and ulcer recurrence rates at 5 years are >58%. To improve the care of patients with venous ulcers, we need to further our understanding of the underlying pathologic events that lead to ulcer formation, prevent healing, and decrease ulcer-free recurrence intervals.

Report of the Society for Vascular Surgery and the American Venous Forum on the July 20, 2016 meeting of the Medicare Evidence Development and Coverage Advisory Committee panel on lower extremity chronic venous disease

On July 20, 2016, a Medicare Evidence Development and Coverage Advisory Committee panel assessed the benefits and risks of currently used lower extremity chronic venous disease (CVD) treatments and their effects on health outcome of the American adult population. The main purpose of the meeting was to advise the Centers for Medicare & Medicaid Services on coverage determination for interventions used for treatment of CVD. A systematic review of the Agency for Healthcare Research and Quality was presented, followed by lectures of invited experts and a public hearing of representatives of professional societies and the industry. After discussing critical issues, the panel voted for key questions. This report summarizes the presented evidence to support recommendations of the Society for Vascular Surgery/American Venous Forum coalition and the presentations on selected discussion topics. These included important venous disease evidence gaps that have not been sufficiently addressed, venous disease treatment disparities and how they may affect the health outcomes of Medicare beneficiaries, and mechanisms that might be supported by the Centers for Medicare & Medicaid Services to improve the evidence base to optimize the care of patients with lower extremity CVD.

Changes in Function After a 6-Month Walking Intervention in Patients With Intermittent Claudication Who Are Obese or Nonobese

BACKGROUND AND PURPOSE

Both obesity and peripheral artery disease (PAD) limit function and may work additively to reduce mobility. The purpose of this study was to compare the effects of a 6-month, center-based walking program on mobility function between adults who are weight-stable obese and nonobese with PAD.

METHODS

This is a secondary data analysis of 2 combined studies taken from previous work. Fifty-three adults with PAD and intermittent claudication participated in 6 months of treadmill training or standard of care. Patients were divided into 4 groups for analyses: exercise nonobese (Ex), exercise obese (ExO), standard-of-care nonobese (SC), and standard-of-care obese (SCO). Mobility was assessed by a standardized treadmill test to measure claudication onset time (COT) and peak walking time (PWT) as well as the distance walked during a 6-minute walk distance (6MWD) test.

RESULTS

There was a significant (P < .001) interaction (intervention × obesity) effect on 6MWD, wherein both exercise groups improved (Ex = 7%, ExO = 16%; P < .02), the SC group did not change (0.9%; P > .05), and the SCO group tended to decline (-18%; P = .06). Both exercise intervention groups significantly improved COT (Ex = 92%, ExO = 102%; P < .01) and PWT (Ex = 54%, ExO = 103%; P < .001). There was no change (P > .05) in either standard-of-care group.

CONCLUSIONS

Individuals who are obese and nonobese with PAD made similar improvements after a 6-month, center-based walking program. However, patients who are obese with PAD and do not exercise may be susceptible to greater declines in mobility. Exercise may be particularly important in patients who are obese with PAD to avoid declines in mobility.

The Society for Vascular Surgery practice guidelines on follow-up after vascular surgery arterial procedures

Although follow-up after open surgical and endovascular procedures is generally regarded as an important part of the care provided by vascular surgeons, there are no detailed or comprehensive guidelines that specify the optimal approaches with regard to testing methods, indications for reintervention, and follow-up intervals. To provide guidance to the vascular surgeon, the Clinical Practice Council of the Society for Vascular Surgery appointed an expert panel and a methodologist to review the current clinical evidence and to develop recommendations for follow-up after vascular surgery procedures. For those procedures for which high-quality evidence was not available, recommendations were based on observational studies, committee consensus, and indirect evidence. Recognizing that there are numerous published reports on the role of duplex ultrasound for surveillance of infrainguinal vein bypass grafts, the Society commissioned a systematic review and meta-analysis on this topic. The panel classified the strength of each recommendation and the corresponding quality of evidence on the basis of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system: recommendations were graded either strong or weak, and the quality of evidence was graded high, moderate, or low. The resulting recommendations represent a wide variety of open surgical and endovascular procedures involving the extracranial carotid artery, thoracic and abdominal aorta, mesenteric and renal arteries, and lower extremity arterial revascularization. The panel also identified many areas in which there was a lack of high-quality evidence to support their recommendations. This suggests that there are opportunities for further clinical research on testing methods, threshold criteria, and the role of surveillance as well as on the modes of failure and indications for reintervention after vascular surgery procedures.

Abstract TP137: Relationship Between Risk Factor Control and Physician Specialty in the CREST2 Trial

Background: In CREST2, intensive medical management of subjects’ vascular risk factors is overseen by the site Principal Investigator (PI) and implemented by a designated Medical Management Physician (MMP) and coordinator. These physicians have different specialties and experience with risk factor management. We sought to determine the relationship between risk factor control and PI and MMP specialty.

Methods: Data on 613 patients with at least 1 follow-up visit from 105 CREST2 sites were used for these analyses. CREST2 sites were categorized based on both PI specialty and MMP specialty. Specialty of the site-designated primary MMP was used for sites with more than one MMP. We compared the percentage of patients in target at last follow-up visit for the primary risk factors, LDL < 70 mg/dL and SBP <140 mm Hg, among PI specialties and MMP specialties, using the chi-square test.

Results: The table shows the number of patients by PI and MMP specialty, as well as their control of SBP and LDL. There were no significant differences in control of SBP or LDL by PI specialty. There was a trend toward an association between LDL control and MMP specialty, with higher rates of LDL control at sites with Internal Medicine MMP specialists and lower rates of control with Vascular Surgery MMPs. SBP control rates were not significantly different across MMP specialties.

Conclusions: In this early analysis of risk factor control in the CREST2 study, site PI and MMP specialty did not have a significant effect on LDL and SBP during follow-up. This suggests that protocol care pathways are generalizable to diverse physicians.

Abstract TP135: Control of Vascular Risk Factors at Baseline in CREST-2

Rationale: Asymptomatic carotid stenosis is commonly seen in medical practice. CREST-2 is a pair of concurrent two-arm multi-site randomized trials of intensive medical management versus intensive medical management in combination with revascularization by endarterectomy or stenting. It is not known how often patients entering the trials have opportunities for further risk factor reduction at study entry and whether these opportunities vary across trial centers.

Methods: Baseline data on 683 patients from 109 clinical sites were used for these analyses. We determined the rates of control at baseline for systolic blood pressure (SBP), defined as <140 mmHg (or ≥140 with >15mmHg orthostatic drop), and low density lipoprotein (LDL), defined as <70 mg/dl. We then tested differences in these baseline control rates by site-related characteristics, including site type, StrokeNet site vs. not, specialty of site Principal Investigator (PI), type of hospital, central vs local IRB, type of research team and whether site is enrolling in one or both trials. P-value <0.05 was considered significant.

Results: At baseline, the mean SBP was 140.4±20.5 mmHg, but only 62% of participants were in target. The mean LDL at baseline was 83.7±36.9, mg/dl, with 42% in target. None of the site characteristics were associated with a higher level of control for SBP at baseline. The only characteristic associated with having a higher level of LDL control was sites enrolling in only the CAS trial (57%) compared to those enrolling in the CEA only (24%) or in both trials (42%) (p=0.02).

Conclusions: Opportunities to improve on risk factors are common among CREST-2 participants, but site characteristics did not predict the likelihood of being at goal for SBP while sites enrolling in only the CAS trial had a higher level of LDL control.

Carotid Endarterectomy and Carotid Artery Stenting in the US Medicare Population, 1999-2014

IMPORTANCE

Carotid endarterectomy and carotid artery stenting are the leading approaches to revascularization for carotid stenosis, yet contemporary data on trends in rates and outcomes are limited.

OBJECTIVE

To describe US national trends in performance and outcomes of carotid endarterectomy and stenting among Medicare beneficiaries from 1999 to 2014.

DESIGN, SETTING, AND PARTICIPANTS

Serial cross-sectional analysis of Medicare fee-for-service beneficiaries aged 65 years or older from 1999 to 2014 using the Medicare Inpatient and Denominator files. Spatial mixed models adjusted for age, sex, and race were fit to calculate county-specific risk-standardized revascularization rates. Mixed models were fit to assess trends in outcomes after adjustment for demographics, comorbidities, and symptomatic status.

EXPOSURES

Carotid endarterectomy and carotid artery stenting.

MAIN OUTCOMES AND MEASURES

Revascularization rates per 100 000 beneficiary-years of fee-for-service enrollment, in-hospital mortality, 30-day stroke or death, 30-day stroke, myocardial infarction, or death, 30-day all-cause mortality, and 1-year stroke.

RESULTS

During the study, 937 111 unique patients underwent carotid endarterectomy (mean age, 75.8 years; 43% women) and 231 077 underwent carotid artery stenting (mean age, 75.4 years; 49% women). There were 81 306 patients who underwent endarterectomy in 1999 and 36 325 in 2014; national rates per 100 000 beneficiary-years decreased from 298 in 1999-2000 to 128 in 2013-2014 (P < .001). The number of patients who underwent stenting ranged from 10 416 in 1999 to 22 865 in 2006 (an increase per 100 000 beneficiary-years from 40 in 1999-2000 to 75 in 2005-2006; P < .001); by 2014, there were 10 208 patients who underwent stenting and the rate decreased to 38 per 100 000 beneficiary-years (P < .001). Outcomes improved over time despite increases in vascular risk factors (eg, hypertension prevalence increased from 67% to 81% among patients who underwent endarterectomy and from 61% to 70% among patients who underwent stenting) and the proportion of symptomatic patients (all P < .001). There were adjusted annual decreases in 30-day ischemic stroke or death of 2.90% (95% CI, 2.63% to 3.18%) among patients who underwent endarterectomy and 1.13% (95% CI, 0.71% to 1.54%) among patients who underwent stenting; an absolute decrease from 1999 to 2014 was observed for endarterectomy (1.4%; 95% CI, 1.2% to 1.5%) but not stenting (-0.1%; 95% CI, -0.5% to 0.4%). Rates for 1-year ischemic stroke decreased after endarterectomy (absolute decrease, 3.5% [95% CI, 3.2% to 3.7%]; adjusted annual decrease, 2.17% [95% CI, 2.00% to 2.34%]) and stenting (absolute decrease, 1.6% [95% CI, 1.2% to 2.1%]; adjusted annual decrease, 1.86% [95% CI, 1.45%-2.26%]). Additional improvements were noted for in-hospital mortality, 30-day stroke, myocardial infarction, or death, and 30-day all-cause mortality as well as within demographic subgroups.

CONCLUSIONS AND RELEVANCE

Among fee-for-service Medicare beneficiaries, the performance of carotid endarterectomy declined from 1999 to 2014, whereas the performance of carotid artery stenting increased until 2006 and then declined from 2007 to 2014. Outcomes improved despite increases in vascular risk factors.

Clinical relevance of the modified physical performance test versus the short physical performance battery for detecting mobility impairments in older men with peripheral arterial disease

PURPOSE

The study is to compare the Modified Physical Performance Test (MPPT) and Short Physical Performance Battery (SPPB) as metrics of mobility and function in older men with peripheral arterial disease (PAD).

MATERIALS AND METHODS

A total of 51 men (55-87 years) with PAD underwent functional testing including the SPPB, MPPT, Walking Impairment Questionnaire (WIQ), stair ascent, and 6-min walk distance. Individuals were grouped according to SPPB and MPPT scores as not limited on either, limited only on the MPPT, or limited on both.

RESULTS

The MPPT identified a higher proportion of patients as being functionally limited than the SPPB (p < 0.001). Men identified as limited only by the MPPT, and not the SPPB, were subsequently confirmed to have lower function on all measures compared to those not identified as limited by either the SPPB or the MPPT (p < 0.02).

CONCLUSIONS

These findings suggest the MPPT is an appropriate measure to identify early declines in men with PAD and may identify global disability better than SPPB. Implications for rehabilitation Individuals with peripheral arterial disease have low activity levels and are at risk for a loss of independence and global disability. Early detection of decline in mobility and global function would allow for interventions before large changes in ambulatory ability or a loss of functional independence occur. This study shows the Modified Physical Performance Test may be an appropriate test to identify early decline in function in men with peripheral arterial disease.

Factors Associated With Time to Site Activation, Randomization, and Enrollment Performance in a Stroke Prevention Trial

BACKGROUND AND PURPOSE

Multicenter clinical trials attempt to select sites that can move rapidly to randomization and enroll sufficient numbers of patients. However, there are few assessments of the success of site selection.

METHODS

In the CREST-2 (Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trials), we assess factors associated with the time between site selection and authorization to randomize, the time between authorization to randomize and the first randomization, and the average number of randomizations per site per month. Potential factors included characteristics of the site, specialty of the principal investigator, and site type.

RESULTS

For 147 sites, the median time between site selection to authorization to randomize was 9.9 months (interquartile range, 7.7, 12.4), and factors associated with early site activation were not identified. The median time between authorization to randomize and a randomization was 4.6 months (interquartile range, 2.6, 10.5). Sites with authorization to randomize in only the carotid endarterectomy study were slower to randomize, and other factors examined were not significantly associated with time-to-randomization. The recruitment rate was 0.26 (95% confidence interval, 0.23-0.28) patients per site per month. By univariate analysis, factors associated with faster recruitment were authorization to randomize in both trials, principal investigator specialties of interventional radiology and cardiology, pre-trial reported performance >50 carotid angioplasty and stenting procedures per year, status in the top half of recruitment in the CREST trial, and classification as a private health facility. Participation in StrokeNet was associated with slower recruitment as compared with the non-StrokeNet sites.

CONCLUSIONS

Overall, selection of sites with high enrollment rates will likely require customization to align the sites selected to the factor under study in the trial.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02089217.

Transcervical Carotid Artery Stenting Using a Prosthetic Arterial Conduit: Case Series of a Novel Surgical Technique

We present a series of 4 patients with carotid restenosis following carotid endarterectomy (CEA) who underwent transcervical carotid artery stenting (CAS) using a novel prosthetic conduit technique. The patients were high risk for repeat CEA (short and obese necks) and had contraindications to transfemoral CAS (bovine arch, prior dissection). CAS was thus performed via a transcervical approach with a polytetrafluoroethylene conduit anastomosed to the proximal common carotid artery. The addition of a conduit allowed stent placement via a secure, stable platform. All patients recovered from their procedure without incident and are free from restenosis at follow-up.

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.

Imaging of high-risk carotid plaques: ultrasound

Duplex ultrasonography has a well-established role in the assessment of the degree of stenosis caused by carotid atherosclerosis. This assessment is derived from Doppler velocity changes induced by the narrowing lumen of the artery. New research into the mechanisms for plaque rupture and atheroembolic stroke indicates that the degree of narrowing is an imperfect predictor of stroke risk, and that other factors, such as plaque composition and remodeling and biomechanical forces acting on the plaque, can play a role. New advances in ultrasound imaging technology have made it possible to investigate these measures of plaque vulnerability to identify pre-embolic unstable carotid plaques. Efforts have been made to quantify the morphologic appearance of the plaque in B-mode images and to correlate them with histology. Additional research has resulted in the first generation of clinically available 3-dimensional ultrasound transducers that reduce operator-dependence and variability. Finally, ultrasonography provides real-time imaging and physiologic information that can be utilized to measure disruptive forces acting on carotid plaques. We review some of these exciting developments in ultrasonography and discuss how these may impact clinical practice.

Asymptomatic carotid stenosis: Medicine alone or combined with carotid revascularization

Two positive randomized trials established carotid endarterectomy (CEA) as a superior treatment to medical management alone for the treatment of asymptomatic carotid artery stenosis. However, advances in medical therapy have led to an active and spirited debate about the best treatment for asymptomatic carotid stenosis. The Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis (CREST 2) trial aims to better define the best treatment for the average patient with severe asymptomatic carotid stenosis. Enrollment in the trial may be hampered by strong opinions on either side of the debate. It is important to realize that equipoise exists and that neither the old data on CEA nor the new data on optimal medical therapy provide a rigorous answer. The assumption that medical therapy has already been proven superior to revascularization procedures may hinder both enrollment in the trial and technical advancements in revascularization procedures.

Clinical viability of carotid plaque strain estimation using B-mode ultrasound image sequences

It is estimated that approximately 30% of ischemic strokes are caused by rupture of plaque in the carotid artery. Development of techniques focusing on identifying plaques that are vulnerable to rupture is thus indispensable for stroke prevention. Recent studies have demonstrated that motion analysis of plaques from B-mode and RF ultrasound (US) image sequences can be used to estimate plaque strain. However, viability of these methods in a clinical setting, with variable acquisition protocols, has not been demonstrated yet. In this paper, we explore the viability of estimating plaque strain from B-mode US images of asymptomatic patients, acquired in a real clinical setting with different acquisition settings, frame rates, and operators. Our proposed strain measures, shear strain rate entropy and variance, combined with the recently reported maximum absolute shear strain rate, show that the plaques fall into two distinct clusters. Moreover, these clusters show good correlations with plaque echolucency and echogenicity. We conclude that B-mode US imaging is a viable tool for characterizing plaque dynamics in clinical environments. In future studies, we plan to implement this method on multi-center studies for longitudinal monitoring of plaque.

Contrast-Enhanced Ultrasound Reveals Exercise-Induced Perfusion Deficits in Claudicants

Background

Contrast-Enhanced Ultrasonography (CEUS) is an imaging modality allowing perfusion quantification in targeted regions of interest of the lower extremity that has not been possible with color-flow imaging or with measurement of ankle brachial indices. We developed a protocol to quantify lower extremity muscle perfusion impairment in PAD patients in response to exercise.

Methods and findings

Thirteen patients with Rutherford Class I-III Peripheral Arterial Disease (PAD) and no prior revascularization procedures were recruited from the Baltimore Veterans Affairs Medical Center and compared with eight control patients without PAD. CEUS interrogation of the index limb gastrocnemius muscle was performed using an intravenous bolus of lipid-stabilized microsphere contrast before and after a standardized treadmill protocol. Peak perfusion (PEAK) and time to peak perfusion (TTP) were measured before and after exercise. Between and within group differences were assessed. Control subjects demonstrated a more rapid TTP (p<0.01) and an increase in peak perfusion (PEAK, p=0.02) after exercise, when compared to their baseline measures. Patients with PAD demonstrated TTP and PEAK measures equivalent to controls at baseline (p=0.39, p=0.71, respectively). However, they exhibited no significant exercise-induced changes in perfusion (TTP p=0.49 and PEAK 0.67, respectively compared to baseline). After exercise, normal subjects had significantly shorter TTP (p=0.04) and greater PEAK (p=0.02) than PAD patients.

Conclusion

Consistent with their lack of ischemic symptoms at rest, class I to III claudicant PAD patients showed similar perfusion measures (TTP and PEAK) at rest. PAD patients, however, were unable to increase perfusion in response to exercise, whereas controls increased perfusion significantly. This corresponds with claudication and limited walking capacity observed in PAD. CEUS with bolus injection offers a convenient, objective, quantitative and visual physiologic assessment of perfusion limitation in specific muscle groups of PAD patients. This has the potential for substantial clinical and research utility.

Abstract TP119: Credentialing of Interventionists in a Large Randomized Trial

Introduction: Outcomes from endovascular procedures are highly dependent on the experience and skill of the operating physician. The multi-disciplinary CREST-2 Interventional Management Committee (IMC) was charged with credentialing a cohort of skilled interventionists with adequate contemporary case volumes.

Methods: Applicants were required to submit 25 consecutive cases completed within 5 years as primary operator out of a required total experience of ≥ 50 cases (≥ 20 for operators completing training). Interventionists not approved on initial review were asked to submit additional cases (with procedural angiograms), the number depending on quality and recent-quantity of the cases.

Results: The IMC has had 102 meetings, and 283 interventionists have been evaluated: 104 (37%) interventionists were cardiologists, 64 (23%) vascular surgeons, 42 (15%) neurosurgeons, 32 (11%) neuroradiologists, 26 (9%) neurologists, 9 (3%) interventional radiologists, and 6 (2%) other. The mean total experience among the 226 interventionists with available information was 220±263 carotid stent cases (median 135; range 10-2500). A total of 7037 cases have been reviewed by the IMC, dating from August 2001 to April 2016, with 3366 symptomatic, 3541 asymptomatic and 130 undetermined. The range of cases reviewed per interventionist was 5 to 50. Of the 251 interventionists with sufficient periprocedural follow-up data, no stroke events were reported by 152 (60.5%), and at least one or more stroke events were reported by 99 (39.5%). The IMC has approved 115 interventionists, 29 at the first review and 86 subsequently, based upon submission and review of 631 additional contemporary cases (mean=7 cases per interventionist); 122 have approval pending submission of additional cases; 33 have been denied; 8 have been deferred; 4 have been approved for the CREST-2 Companion Registry only; and 1 is pending decision.

Discussion: Rigorous evaluation and credentialing of carotid stenters in CREST-2 has been demanding, for the candidates and for the evaluators. Yet the cohort of interventionists so selected should be able to provide the high-quality stenting outcomes necessary for acceptance of the trial results.

Abstract TP132: Selection and Activation of Sites in a Large Multi-Center Randomized Clinical Trial

Introduction: Careful selection and timely activation of clinical sites in multicenter clinical trials is critical for successful enrollment, subject safety, and generalizability of results.

Methods: In the Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trial (CREST-2), a multidisciplinary Site Selection Committee evaluated applicants referred via participation in CREST, CREST principal investigators (PIs) and other investigators, StrokeNet and industry partners. Data for consideration included performance metrics in CREST and other carotid trials and a site selection questionnaire containing information on the investigators as well as quantitative data on carotid procedures performed. Any FDA warning letters were reviewed.

Results: The Committee met bi-weekly for 36 months (n=64 meetings). Applications from 176 sites between March 2014 and July 2016 were evaluated: 153 were approved, 7 are under Committee review, 5 were approved but withdrew, 5 were placed on a waiting list, and 6 were rejected. One-hundred-four sites have completed the regulatory and training requirements to randomize: 51 (49%) academic medical centers, 31 (30%) private hospital-based centers, 16 (15%) private office-based practices, and 6 (6%) Veterans Administration medical centers. The mean times from application-to- approval was 5.2 weeks (interquartile range, 1.9, 6.2), and from approval-to-randomization status was 46.7 weeks (interquartile range, 35.4, 51.7). Specialties of the 104 site PIs are vascular surgery for 35 (33.7%), cardiology for 30 (28.8%), neurology for 25 (24%), neurosurgery for 8 (7.7%), interventional radiology for 4 (3.8%), and interventional neuroradiology for 2 (1.9%).

Conclusions: Careful site selection is time-consuming for prospective sites and for trial leadership. Times from application-to-site-approval were modest (mean = 5.2 weeks), in contrast to the times for completing regulatory and training requirements (mean = 46.7 weeks). However, subject enrollment by teams from a wide range of medical centers led by a multi-disciplinary cohort of PIs will promote the generalizability of trial results.

Improvement in patient-reported outcomes of varicose veins following treatment with polidocanol endovenous microfoam

Objective

To evaluate the relationship between patient-reported symptoms and functional and psychological impact of varicose veins following treatment with polidocanol endovenous microfoam (PEM) 1%.

Methods

Data were pooled from two randomized trials on VV treatment. Wilson–Cleary health outcomes path model was applied to evaluate impact of VVSymQ™ symptom score improvement on modified VEINES-QOL/Sym functional and psychological scores. Change scores were evaluated for (i) PEM 1% versus placebo groups and (ii) quartiles of symptom improvement. Cumulative distribution function curves were generated to compare percentage of patients with various levels of functional and psychological improvement including clinically meaningful improvement across two treatment groups. Multivariable regression models of change scores and clinically meaningful changes were estimated.

Results

In 221 patients (109 PEM 1%; 112 placebo), PEM 1% was associated with median improvements of 2.5 points and 4.0 points on the m-VEINES-QOL/Sym functional limitations and m-VEINES-QOL/Sym psychological limitations scores, compared to 0 and 1.0 point improvements, respectively, for placebo. Cumulative distribution function curves revealed that 20–30% more patients in PEM 1% group achieved clinically meaningful functional and psychological improvement versus placebo group.

Conclusions

Patients with above-average symptom improvement had better functional and psychological improvement. PEM 1% treatment had higher odds of clinically meaningful functional and psychological improvement.