The CARE Registry®
was launched in 2007 by the NCDR®
(National Cardiovascular Data Registry) as a nationwide program for carotid revascularization procedures to measure patient outcomes and ensure quality improvement. A description of CARE has been previously published5
. Briefly, 186 centers in the United States voluntarily participate in collection and validation of demographic, medical history, and procedural data from patients undergoing either CAS or CEA. Data are collected from existing medical records using standardized definitions, collection protocols, and tools. An on-site registry manager is designated by each participating center to ensure data accuracy and timely submission to NCDR.
For the purpose of this study, we identified patients with and without a CCO undergoing elective CAS between 05/2005 and 03/2010. Patients were stratified by presence or absence of neurologic symptoms related to the target lesion within the past 6 months and by age <70 or ≥ 70. Patients with an acute evolving stroke (AES) including acute cerebrovascular accident in evolution or transient ischemic attack (N=204), or spontaneous carotid artery dissection (N =93) were excluded. AES required the patient to have ongoing ischemia with symptoms at the time of the procedure. AES also required each of the following: Sudden development of neurologic deficits attributable to cerebral ischemia or infarction, onset of symptoms occurring within the prior 3 days of CAS and progressively worsening symptomatology.
CCO was defined as a 100% occluded contralateral internal carotid artery. The CCO indicator was missing in one patient.
The primary clinical endpoint was a composite of in-hospital death, nonfatal myocardial infarction or nonfatal stroke. Secondary endpoints were the individual components of the composite.
Post CAS ischemic stroke was defined as a focal neurologic deficit in the absence of documented intracranial hemorrhage with residual symptoms lasting ≥24 hours and combined with impaired functional outcomes. Symptoms of ischemic stroke were identified as 1) right hemispheric or retinal, 2) left hemispheric or retinal, 3) vertebrobasilar, or 4) unknown.
Post CAS myocardial infarction was identified by an increase and decrease in cardiac biomarkers (preferably troponin) with >1 value above the upper limit of normal along with clinical evidence of myocardial ischemia consisting of ≥1 of the following: 1) symptoms, 2) electrocardiographic (ECG) changes (new ST-T changes or left bundle branch block), 3) development of pathological Q waves in the ECG, or 4) new loss of viable myocardium or new regional wall motion abnormality as evidenced by imaging6
. Cardiac biomarkers were collected at the discretion of each participating investigator following CAS.
Neurologic symptoms status in the target lesion was determined in all patients prior to CAS. Symptomatic patients had history of prior carotid transient ischemic attack with distinct focal logical dysfunction persisting less than 24 hours, nondisabling stroke with a modified Rankin scale less than 3 and symptoms greater than 24 hours or transient monocular blindness (amaurosis fugax) within the previous six months.
An acute cerebrovascular accident was classified as sudden development of a neurological deficit attributable to cerebral ischemia or infarction, symptom onset within 3 days prior to and ongoing at the time of procedure, or progressively worsening numbness or weakness, difficulty speaking or understanding, blurred or impaired vision, dizziness, or loss of balance and coordination.
Data are presented as means with corresponding 95% confidence intervals (CI), counts with percentages, or medians with interquartile ranges. Baseline characteristics of patients with and without CCO undergoing elective CAS were compared using chi-square tests for discrete variables and Student’s unpaired t-tests for continuous variables. To address potential confounder in the primary endpoint, a saturated multivariable logistic regression model was developed to predict the primary outcome while adjusting for: age, gender, renal function, smoking, hypertension, hyperlipidemia, peripheral arterial disease, diabetes, chronic obstructive pulmonary disease, major surgery planned within the next 8 weeks, previous neck radiation or neck surgery (other than CEA), ischemic heart disease, myocardial infarction within the past 6 weeks, Canadian Cardiovascular Society (CCS) or New York Heart Association (NYHA) functional class III or IV heart failure within the past 6 weeks, history of atrial fibrillation or flutter, moderate to severe aortic stenosis, previous carotid artery intervention, neurological events prior to the CAS procedure, target lesion symptoms within the past 6 months, and restenosis in the target vessel after prior CAS or CEA.
Results are reported as unadjusted and adjusted odds ratios (OR) with 95% CI for the primary and secondary endpoints. For individual endpoints with no events, exact logistic regression was used to obtain ORs (95% CI). The primary endpoint was also stratified by asymptomatic and symptomatic patients and by age less than or greater than or equal to 70 years. All statistical analyses were performed using the SAS version 9.2 (SAS Institute, Cary, North Carolina). A two-sided p-value ≤ 0.05 was considered statistically significant.