Body mass index and outcome after revascularization for symptomatic carotid artery stenosis

OBJECTIVE

To determine whether the obesity paradox exists in patients who undergo carotid artery stenting (CAS) or carotid endarterectomy (CEA) for symptomatic carotid artery stenosis.

METHODS

We combined individual patient data from 2 randomized trials (Endarterectomy vs Angioplasty in Patients with Symptomatic Severe Carotid Stenosis and Stent-Protected Angioplasty vs Carotid Endarterectomy) and 3 centers in a third trial (International Carotid Stenting Study). Baseline body mass index (BMI) was available for 1,969 patients and classified into 4 groups: <20, 20-<25, 25-<30, and ≥30 kg/m². Primary outcome was stroke or death, investigated separately for the periprocedural and postprocedural period (≤120 days/>120 days after randomization). This outcome was compared between different BMI strata in CAS and CEA patients separately, and in the total group. We performed intention-to-treat multivariable Cox regression analyses.

RESULTS

Median follow-up was 2.0 years. Stroke or death occurred in 159 patients in the periprocedural (cumulative risk 8.1%) and in 270 patients in the postprocedural period (rate 4.8/100 person-years). BMI did not affect periprocedural risk of stroke or death for patients assigned to CAS (p_trend = 0.39) or CEA (p_trend = 0.77) or for the total group (p_trend = 0.48). Within the total group, patients with BMI 25-<30 had lower postprocedural risk of stroke or death than patients with BMI 20-<25 (BMI 25-<30 vs BMI 20-<25; hazard ratio 0.72; 95% confidence interval 0.55-0.94).

CONCLUSIONS

BMI is not associated with periprocedural risk of stroke or death; however, BMI 25-<30 is associated with lower postprocedural risk than BMI 20-<25. These observations were similar for CAS and CEA.

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.

Abstract 208: Periprocedural Stroke and Myocardial Infarction as Risks for Long-term Mortality in CREST

Introduction: Occurrence of stroke and myocardial infarction (MI) after carotid endarterectomy or stenting have each been associated with increased later mortality.

Methods: In the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) 69 strokes, 37 protocol MIs, and 19 biomarker + only events occurred within 30 days among 2272 patients followed up to 10 years. Mortality was determined and compared for patients with stroke, MI, or biomarker + only to those without. Cox proportional hazard models adjusting for age, sex, symptomatic status and treatment were calculated to assess the relationship between mortality and stroke and mortality and MI status. Kaplan-Meier survival curves were plotted.

Results: Patients with peri-procedural stroke had a 67% greater likelihood of long-term mortality compared to those without stroke (HR=1.67, 95% CI 1.15,2.43; p<0.007)(Figure A). Patients with a protocol MI had a 249% greater likelihood of mortality, and biomarker+ only patients had a 104% greater likelihood of mortality, compared to those without MI (HR=3.49; 95%CI 2.20,5.53, p<0.0001; and HR=2.04; 95% CI 1.09,3.83, p=0.03)(Figure B).

Discussion: Stroke, MI, and biomarker + only events following CEA or CAS are associated with increased long-term mortality. The higher risk for MI may be a marker for patients with serious underlying heart disease, rather than causal, providing an opportunity to decrease long-term mortality through aggressive diagnostic evaluation and preventive treatment.

Abstract TMP34: The Challenge and Yield of Racially and Ethnically Diverse Patient Populations in Low Event-Rate Clinical Trials

Background: Concern for underrepresentation of minorities in clinical trials has focused on enrollment proportions and generalizability. The interplay of trial event-rates with diversity has not been emphasized.

Methods: The Carotid Revascularization Endarterectomy vs Stent Trial (CREST) randomized 2502 patients and compared them by race, ethnicity, baseline characteristics, and primary outcome (any peri-procedural stroke, death or MI and subsequent ipsilateral stroke up to 10 years); those with unknown race or ethnicity were excluded. Proportional hazards models adjusting for age, sex, symptomatic status and treatment were used to test for a treatment by race/ethnicity interaction.

Results: One-hundred-nine patients (4.4%) were black, 32 (1.3%) Asian, 2332 (93.4%) white, 11 (0.4%) other by self-report, and 18 (0.7%) unknown; 90 (3.6%) were Hispanic, 2377 (95%) non-Hispanic, and 35 (1.4%) unknown. Compared to whites, racial minorities were younger (mean age 67±8.9 vs 69±8.8, p=0.004), more often female (44% vs 34%, p=0.01), symptomatic (63 vs 52%, p=0.01), and diabetic (51% vs 29%, p<0.0001), but less often dyslipidemic (76% vs 85%, p=0.004), current smokers (19% vs 27%, p=0.04), or had a history of cardiovascular disease (34% vs 46%, p=0.007). Hispanics were more often diabetic (48% vs 30%, p=0.0002). The rate of the primary endpoint was 10.9%±0.9% at 10 years, and did not differ by race or ethnicity (p inter >0.24). In the context of this low rate, even if minority recruitment were increased to represent 50% of study participants, and if the treatment difference in one race were a greater hazard of HR = 1.49 (anticipated alternative hypothesis), then the hazard ratio in the other group would need to be <0.73, or >3.31, to have 90% power of detection.

Conclusions: The proportion of racial and ethnicity participation in CREST was suboptimal at < 10%. Primary outcomes did not differ by minority or ethnic status. However, in low event-rate trials very high and even unrealistic enrollment goals for diversity, for example ≥50%, may still be insufficient for detection of outcome differences by race or ethnicity.

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.

Carotid Stenting Versus Carotid Endarterectomy: What Did the Carotid Revascularization Endarterectomy Versus Stenting Trial Show and Where Do We Go From Here?

Although rapidly expanding in its use, carotid artery stenting remains a relatively new procedure. Its growth is due, at least in part, to the perceived advantages of a less invasive technique. However, the clinical effectiveness and specific role for stenting in the treatment of carotid occlusive disease are still under evaluation. The primary aim of the randomized clinical trial, Carotid Revascularization Endarterectomy versus Stenting Trial (CREST), was to contrast the relative efficacy of carotid stenting versus carotid endarterectomy in preventing stroke, myocardial infarction, or death during a 30-day periprocedural period or ipsilateral stroke over the follow-up period in patients with symptomatic and asymptomatic extracranial carotid stenosis. The secondary goals were to describe the differential efficacy of the 2 procedures in men and women, contrast periprocedural (30-day) morbidity and postprocedural morbidity and mortality, estimate and contrast the restenosis rates of the 2 procedures, evaluate differences in measures of health-related quality of life and cost-effectiveness, and identify subgroups of participants at differential risk of stenting or surgery. This report summarizes the results obtained from CREST with respect to its primary and secondary aims.

Association between age and risk of stroke or death from carotid endarterectomy and carotid stenting: a meta-analysis of pooled patient data from four randomised trials

BACKGROUND

Age was reported to be an effect-modifier in four randomised controlled trials comparing carotid artery stenting (CAS) and carotid endarterectomy (CEA), with better CEA outcomes than CAS outcomes noted in the more elderly patients. We aimed to describe the association of age with treatment differences in symptomatic patients and provide age-specific estimates of the risk of stroke and death within narrow (5 year) age groups.

METHODS

In this meta-analysis, we analysed individual patient-level data from four randomised controlled trials within the Carotid Stenosis Trialists' Collaboration (CSTC) involving patients with symptomatic carotid stenosis. We included only trials that randomly assigned patients to CAS or CEA and only patients with symptomatic stenosis. We assessed rates of stroke or death in 5-year age groups in the periprocedural period (between randomisation and 120 days) and ipsilateral stroke during long-term follow-up for patients assigned to CAS or CEA. We also assessed differences between CAS and CEA. All analyses were done on an intention-to-treat basis.

FINDINGS

Collectively, 4754 patients were randomly assigned to either CEA or CAS treatment in the four studies. 433 events occurred over a median follow-up of 2·7 years. For patients assigned to CAS, the periprocedural hazard ratio (HR) for stroke and death in patients aged 65-69 years compared with patients younger than 60 years was 2·16 (95% CI 1·13-4·13), with HRs of roughly 4·0 for patients aged 70 years or older. We noted no evidence of an increased periprocedural risk by age group in the CEA group (p=0·34). These changes underpinned a CAS-versus CEA periprocedural HR of 1·61 (95% CI 0·90-2·88) for patients aged 65-69 years and an HR of 2·09 (1·32-3·32) for patients aged 70-74 years. Age was not associated with the postprocedural stroke risk either within treatment group (p≥0·09 for CAS and 0·83 for CEA), or between treatment groups (p=0·84).

INTERPRETATION

In these RCTs, CEA was clearly superior to CAS in patients aged 70-74 years and older. The difference in older patients was almost wholly attributable to increasing periprocedural stroke risk in patients treated with CAS. Age had little effect on CEA periprocedural risk or on postprocedural risk after either procedure.

FUNDING

None.

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.).

Anesthetic type and risk of myocardial infarction after carotid endarterectomy in the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST)

OBJECTIVE

Carotid endarterectomy (CEA) is usually performed under general anesthesia (GA), although some advocate regional anesthesia (RA) to reduce hemodynamic instability and allow neurologic monitoring and selective shunting. RA does not reduce risk of periprocedural stroke or death, although some series show a reduction in myocardial infarction (MI). We investigated the association of anesthesia type and periprocedural MI among patients receiving GA or RA for CEA and patients undergoing carotid artery stenting (CAS) in the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST).

METHODS

Between 2000 and 2008, 1151 patients underwent CEA (anesthetic type available for 1149 patients), and 1123 patients underwent CAS ≤30 days of randomization in CREST. CEA patients were categorized by anesthetic type (GA vs RA). CREST defined protocol MI as chest pain or electrocardiogram change plus biomarker evidence of MI, and total MI was defined as protocol MI plus biomarker-positive (+)-only MI. The incidence of protocol MI and total MI in patients undergoing CEA under GA and RA were compared with those undergoing CAS. Other study end points were similarly compared. Differences in baseline characteristics and periprocedural events were evaluated among the three groups. Logistic regression, adjusting for age and symptomatic status, was used to assess group differences.

RESULTS

The three groups had similar demographic risk factors, except for prevalence of symptomatic carotid stenosis, which was lowest in the CEA-RA group (P = .03). Of the 111 patients in the CEA-RA group, no protocol MIs occurred and only two biomarker+-only MIs, for an overall incidence of 1.8%, similar to the 1.7% overall incidence in patients undergoing CAS. In contrast, the combined incidence of protocol and biomarker+-only MIs in the 1038 patients in the CEA-GA group was significantly higher at 3.4% (P = .04), twice the risk of protocol MI and biomarker+-only MI compared with those undergoing CAS (odds ratio [OR], 2.01; 95% confidence interval [CI], 1.14-3.54). Direct comparison of the MI incidence between CEA-RA and CEA-GA showed no statistical difference. Patients undergoing CEA-GA had lower odds of a periprocedural stroke (OR, 0.48; 95% CI, 0.28-0.79) and stroke or death (OR, 0.46; 95% CI, 0.27-0.76) compared with those undergoing CAS but were not significantly different from those undergoing CEA-RA.

CONCLUSIONS

Patients in CREST undergoing CEA-RA had a similar risk of periprocedural MI as those undergoing CAS, whereas the risk for CEA-GA was twice that compared with patients undergoing CAS. Nevertheless, because periprocedural MI is one of the few variables favoring CAS over CEA and has been associated with decreased long-term survival, RA should be seriously considered for patients undergoing CEA.

Vascular Cell Senescence Contributes to Blood-Brain Barrier Breakdown

BACKGROUND AND PURPOSE

Age-related changes in the cerebrovasculature, including blood-brain barrier (BBB) disruption, are emerging as potential risks for diverse neurological conditions. Because the accumulation of senescent cells in tissues is increasingly recognized as a critical step leading to age-related organ dysfunction, we evaluated whether senescent vascular cells are associated with compromised BBB integrity.

METHODS

Effects of vascular cell senescence on tight junction and barrier integrity were studied using an in vitro BBB model, composed of endothelial cells, pericytes, and astrocytes. In addition, tight junction coverage in microvessels and BBB integrity in BubR1 hypomorphic (BubR1(H/H)) mice, which display senescence cell-dependent phenotypes, were examined.

RESULTS

When an in vitro BBB model was constructed with senescent endothelial cells and pericytes, tight junction structure and barrier integrity (evaluated by transendothelial electric resistance and tracer efflux assay using sodium fluorescein and Evans blue-albumin were significantly impaired. Endothelial cells and pericytes from BubR1(H/H) mice had increased senescent-associated β-galactosidase activity and p16(INK4a) expression, demonstrating an exacerbation of senescence. The coverage by tight junction proteins in the cortical microvessels were reduced in BubR1(H/H) mice, consistent with a compromised BBB integrity from permeability assays. Importantly, the coverage of microvessels by end-feet of aquaporin 4-immunoreactive astrocytes was not altered in the cortex of the BubR1(H/H) mice.

CONCLUSIONS

Our results indicate that accumulation of senescent vascular cells is associated with compromised BBB integrity, providing insights into the mechanism of BBB disruption related to biological aging.

Abstract WP332: Updating the Structure of Stroke Clinical Research Data: Version 2 of the Stroke Common Data Elements From the National Institutes of Health/National Institute of Neurological Disorders and Stroke

Introduction: In order to increase the efficiency and effectiveness of neurovascular clinical research studies, increase data quality, facilitate data sharing, help educate new clinical investigators and reduce study start-up time, the National Institute of Neurological Disorders and Stroke (NINDS) convened a Working Group (WG) that developed Version 1.0 (published 2010) Stroke-specific Common Data Elements (CDEs). Since their initial publication, intervening advances in science and initial experience with the CDEs identified a need to update them and refine guidance on their deployment.

Hypothesis/Objective: The NINDS has updated guidance on uniform data structures for use in cerebrovascular research in epidemiology, clinical trials and imaging studies in order to advance the prevention, acute treatment and recovery from cerebrovascular disease.

Methods: The NINDS convened experts in research and data element design drawing strongly from investigators in the NIH StrokeNet and other NINDS clinical research projects.

Results: Stroke CDE leadership developed a revised process for classifying Stroke CDEs among the four hierarchical categories of Core, Supplemental - Highly Recommended, Supplemental and Exploratory. Due to the heterogeneity of stroke conditions and study types, the classification of Supplemental - Highly Recommended was used for study type (clinical trial or observational), disease type (e.g., ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage) and disease phase (primary prevention, acute, recovery and secondary prevention).

Conclusion: The second iteration of NINDS CDE recommendations for neurovascular disease is an important step towards more efficient study start-up time and improved data sharing. The updated CDEs were released on the NINDS CDE website in May 2015. The information at this meeting will include examples of how the Stroke CDEs may be used by a research study, an explanation of the new CDE classifications, and examples of navigating and selecting CDEs from the NINDS CDE website.

Support: This project was funded by HHSN271201200034C.

Abstract TMP10: A Retrospective Comparison of Medical Eligibility for Acute Ischemic Stroke Clinical Trials Compared with Hospital Enrollment Rates: Greater Cincinnati/Northern Kentucky Population

Introduction: Low rates of enrollment into stroke clinical trials are an ongoing challenge for the stroke research community. We sought to retrospectively describe the association between medical eligibility and recruitment rates for two acute clinical trials.

Methods: Within a population of 1.3 million, we screened local hospital admissions in 2010 using ICD-9 discharge codes 430-436, and performed chart review. Within the region are 15 adult acute care hospitals, all of which are covered by the same stroke team for clinical care and trial enrollment. Medical eligibility, the number of eligible patients/total number of patients, was calculated for the IMS-III trial and the CLEAR-ER trials using their inclusion/exclusion criteria. The number of patients enrolled in the trial per month of open enrollment was determined for each hospital. Statistical analysis included paired signed rank test and regression.

Results: In 2010, 2035 ischemic strokes (IS) were hospitalized in the region. Regional medical eligibility was 1.7% for IMS III and 4.5% for CLEARER (p=0.001), overall regional hospital enrollment/month was 0.81 for IMS III and 1.84 for CLEAR-ER (p=0.001). Eligibility rates per hospital ranged from 0-9.5%, and recruitment rates per hospital/mo ranged from 0-0.38. Hospital-level eligibility and recruitment rates were significantly correlated (see figure for both trials combined, adjusted r2 = 0.57, p<0.001.)

Discussion: Within our population, medical eligibility explained 57% of the variability in hospital-level enrollment rates for two acute IS trials. The use of population-based epidemiology in trial planning may identify optimal trial enrollment criteria, which must be weighed against proper patient selection. Many other factors impact enrollment rates, such as competing trials, which were not considered here. Further evaluation of our population-based eligibility rates in sites outside our region and with additional clinical trials is needed.

Abstract TP131: Degree of Stenosis by Angiography Does not Influence Risk of Endarterectomy or Stenting in Patients With Severe Asymptomatic Carotid Stenosis

Introduction: Increasing stenosis has been questioned as a factor increasing risk of carotid endarterectomy (CEA) or carotid stenting (CAS) in patients with severe asymptomatic carotid stenosis.

Hypothesis: Greater severity of carotid stenosis is associated with higher rates of periprocedural stroke and death following revascularization for asymptomatic patients.

Methods: Asymptomatic patients with carotid stenosis ≥ 70% by ultrasound or ≥ 60% by angiogram were eligible for the Carotid Revascularization Endarterectomy vs Stenting Trial (CREST). Patients who had a catheter-angiogram were divided into tertiles based on the degree of stenosis. Outcomes were the occurrence of any stroke or death at 30 days. Proportional hazards models adjusting for age and treatment were used to assess risk of 30 day stroke or death by tertile of stenosis.

Results: Among 1181 asymptomatic patients, qualifying angiograms were done for 662 patients who had assigned procedure performed within 30 days of randomization. Median % stenosis was 62.6, 73.4, and 83.0 for the tertiles that otherwise differed only for female sex (40% female in tertile 1, 36% in tertile 2, 29% in tertile 3, p=0.01). The 30-day stroke and death rates did not differ significantly by severity of stenosis (Table), but the number of stroke and deaths was only 14 across the tertiles (Table). Similarly meaningful comparison of CEA vs CAS was not possible.

Conclusion: This is the largest contemporary study of carotid angiograms performed in patients with severe asymptomatic carotid stenosis. No relationship was detected between severity of stenosis and 30-day stroke and death. The safety of CEA and CAS in asymptomatic patients limits detection of other factors that may increase risk because so few events complicate these procedures.

Abstract 15: Trends in Performance and Outcomes of Carotid Endarterectomy Among Elderly Medicare Beneficiaries, 2003-2010

Background: Carotid endarterectomy (CEA) is the leading procedure for carotid stenosis, yet national data on trends in rates and outcomes are limited. We determined CEA rates among Medicare beneficiaries and evaluated mortality and readmission over 8 years.

Methods: We used Medicare fee-for-service data to identify beneficiaries aged ≥65y who had their first CEA (ICD-9 38.12) from 2003-2010 and calculated annual rates per 100,000 person-years (PY). We fit mixed models to assess trends in patient-level outcomes, adjusting for demographics, comorbidities, and symptomatic status. We also evaluated hospital-level trends by calculating risk-standardized mortality (RSMR) and readmission (RSRR) rates. A spatial mixed model adjusted for age, sex, and race was fit to calculate county-specific risk-standardized CEA rates in 2003-2004.

Results: There were 505,966 unique CEA hospitalizations. The annual number of CEA discharges decreased from 81,604 in 2003 to 47,597 in 2010 (42% decrease), though the patient characteristics remained largely similar. The national CEA rate was 283 per 100,000 PY in 2003, and there was considerable geographic variability (Figure A). This rate decreased each year to a low of 172 per 100,000 PY in 2010. The rate of stroke or death within 30 days decreased from 3.2 to 2.7%, with a significant adjusted annual reduction of 3% (Figure B). Annual reductions in other short- and long-term outcomes were similar, ranging from 2-3%. The median hospital-level 30-day RSMR decreased over time from 0.99 to 0.57%, while the variation between hospitals increased (interquartile range of 0.7-1.67 percentage points). The 30-day RSRR decreased from 11.0 to 10.1%, but there was more homogeneity across hospitals and years.

Conclusions: CEA use among Medicare patients decreased dramatically from 2003-2010, while mortality and readmission outcomes improved. The relative importance of biological and sociological mechanisms for these trends merits further study.

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.

Time From Symptoms to Carotid Endarterectomy or Stenting and Perioperative Risk

BACKGROUND AND PURPOSE

Prior meta-analysis showed that carotid endarterectomy benefits decline with increasing surgical delay following symptoms. For symptomatic patients in the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST), we assessed if differences in time between symptoms and carotid endarterectomy or carotid artery stenting are associated with differences in risk of periprocedural stroke or death.

METHODS

We analyzed the 1180 symptomatic patients in CREST who received their assigned procedure and had clearly defined timing of symptoms. Patients were classified into 3 groups based on time from symptoms to procedure: <15, 15 to 60, and >60 days.

RESULTS

For carotid endarterectomy, risk of periprocedural stroke or death was not significantly different for the 2 later time periods relative to the earliest time period (hazard ratio, 0.74; 95% confidence interval, 0.22-2.49 for 15-60 days and hazard ratio, 0.91; 95% confidence interval, 0.25-3.33 for >60 days; P=0.89). For carotid artery stenting, risk of periprocedural stroke or death was also not significantly different for later time periods relative to the earliest time period (hazard ratio, 1.12; 95% confidence interval, 0.53-2.40 for 15-60 days and hazard ratio, 1.15; 95% confidence interval, 0.48-2.75 for >60 days; P=0.93).

CONCLUSIONS

Time from symptoms to carotid endarterectomy or carotid artery stenting did not alter periprocedural safety, supporting early revascularization regardless of modality.

CLINICAL TRIAL REGISTRATION

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

Mediators of the Age Effect in the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST)

BACKGROUND AND PURPOSE

There is higher combined risk of stroke or death (S+D) at older ages with carotid stenting. We assess whether this can be attributed to patient or arterial characteristics that are in the pathway between older age and higher risk.

METHODS

Mediation analysis of selected patient (hypertension, diabetes mellitus, and dyslipidemia) and arterial characteristics assessed at the clinical sites and the core laboratory (plaque length, eccentric plaque, ulcerated plaque, percent stenosis, peak systolic velocity, and location) was performed in 1123 carotid artery stenting-treated patients in the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST). We assessed the association of age with these characteristics, the association of these characteristics with stroke risk, and the amount of mediation of the association of age on the combined risk of periprocedural S+D with adjustment for these factors.

RESULTS

Only plaque length as measured at the sites increased with age, was associated with increased S+D risk and significantly mediated the association of age on S+D risk. However, adjustment for plaque length attenuated the increased risk per 10 years of age from 1.72 (95% confidence interval, 1.26-2.37) to 1.66 (95% confidence interval, 1.20-2.29), accounting for only 8% of the increased risk.

CONCLUSIONS

Plaque length seems to be in the pathway between older age and higher risk of S+D among carotid artery stenting-treated patients, but it mediated only 8% of the age effect excess risk of carotid artery stenting in CREST. Other factors and mechanisms underlying the age effect need to be identified as plaque length will not identify elderly patients for whom stenting is safe relative to endarterectomy.

CLINICAL TRIAL REGISTRATION

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

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.

Characteristics of participants consenting versus declining follow-up for up to 10 years in a randomized clinical trial

BACKGROUND

With patients living a decade or longer post-procedure, long-term data are needed to assess the durability of carotid artery stenting versus carotid endarterectomy. Identifying characteristics of those consenting or declining to continue in long-term follow-up may suggest strategies to improve retention in clinical trials.

PURPOSE

This report describes differences between patients choosing or declining to continue follow-up for up to 10 years in the Carotid Revascularization Endarterectomy versus Stenting Trial.

METHODS

Following completion of the primary outcome, patients who were in active Carotid Revascularization Endarterectomy versus Stenting Trial follow-up were asked to continue beyond their original 4-year commitment for a maximum of 10 years. The characteristics of those who consented were compared with those who declined. Univariate and multivariable logistic regression were used for analysis, and backwards stepwise logistic regression (the most parsimonious model) was used to determine the factors associated with continuation.

RESULTS

Of the 1921 active Carotid Revascularization Endarterectomy versus Stenting Trial participants for whom consent to extend follow-up was requested, 1695 (88%; mean age: 68.4) consented; 226 (12%; mean age: 69.6) declined. Of those who did not consent versus those who consented, 66% versus 48% were symptomatic at baseline (p<0.0001), at follow-up 28% versus 20% were smokers (p=0.009), 85% versus 90% were hypertensive (p=0.01), and 84% versus 94% were dyslipidemic (p<0.0001). Additional factors that differed between those who did not consent and those who consented included the mean number of years in the study at time of consent (4.8 years vs 3.7 years (p=<0.0001)) and patients from sites that enrolled <30 patients compared to sites randomizing 30 or more (70% vs 52% (p<0.0001)). Multivariable logistic regression indicated that those with lesser odds of consenting to the extended follow-up were older (odds ratio: 0.80; 95% confidence interval: 0.67, 0.96), more likely to be symptomatic (odds ratio: 0.58; 95% confidence interval: 0.42, 0.80), smokers (odds ratio: 0.48; 95% confidence interval: 0.34, 0.70), were in the study 5+ years versus <3 (odds ratio: 0.21; 95% confidence interval: 0.13, 0.34), and at a site that randomized <30 patients (odds ratio: 0.46; 95% confidence interval: 0.33, 0.63), while patients with dyslipidemia at follow-up had increased odds of consenting (odds ratio: 2.28 (1.47, 3.54)).

CONCLUSION

Symptomatic status, increasing age, randomized at lower volume centers, and longer time in follow-up were associated with reduced odds of consenting to long-term follow-up. Identifying factors associated with reduced willingness to extend participation long-term can suggest targeted strategies to improve retention in future clinical trials.