Stanley N. Cohen

Stenting versus Endarterectomy for Treatment of Carotid-Artery Stenosis

BACKGROUND Carotid-artery stenting and carotid endarterectomy are both options for treating carotid-artery stenosis, an important cause of stroke. METHODS We randomly assigned patients with symptomatic or asymptomatic carotid stenosis to undergo carotid-artery stenting or carotid endarterectomy. The primary composite end point was stroke, myocardial infarction, or death from any cause during the periprocedural period or any ipsilateral stroke within 4 years after randomization. RESULTS For 2502 patients over a median follow-up period of 2.5 years, there was no significant difference in the estimated 4-year rates of the primary end point between the stenting group and the endarterectomy group (7.2% and 6.8%, respectively; hazard ratio with stenting, 1.11; 95% confidence interval, 0.81 to 1.51; P=0.51). There was no differential treatment effect with regard to the primary end point according to symptomatic status (P=0.84) or sex (P=0.34). The 4-year rate of stroke or death was 6.4% with stenting and 4.7% with endarterectomy (hazard ratio, 1.50; P=0.03); the rates among symptomatic patients were 8.0% and 6.4% (hazard ratio, 1.37; P=0.14), and the rates among asymptomatic patients were 4.5% and 2.7% (hazard ratio, 1.86; P=0.07), respectively. Periprocedural rates of individual components of the end points differed between the stenting group and the endarterectomy group: for death (0.7% vs. 0.3%, P=0.18), for stroke (4.1% vs. 2.3%, P=0.01), and for myocardial infarction (1.1% vs. 2.3%, P=0.03). After this period, the incidences of ipsilateral stroke with stenting and with endarterectomy were similarly low (2.0% and 2.4%, respectively; P=0.85). CONCLUSIONS Among patients with symptomatic or asymptomatic carotid stenosis, the risk of the composite primary outcome of stroke, myocardial infarction, or death did not differ significantly in the group undergoing carotid-artery stenting and the group undergoing carotid endarterectomy. During the periprocedural period, there was a higher risk of stroke with stenting and a higher risk of myocardial infarction with endarterectomy. (ClinicalTrials.gov number, NCT00004732.)

Carotid endarterectomy--an evidence-based review: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology.

Objective: To assess the efficacy of carotid endarterectomy for stroke prevention in asymptomatic and symptomatic patients with internal carotid artery stenosis. Additional clinical scenarios, such as use of endarterectomy combined with cardiac surgery, are also reviewed. Methods: The authors selected nine important clinical questions. A systematic search was performed for articles from 1990 (the year of the last statement) until 2001. Additional articles from 2002 through 2004 were included using prespecified criteria. Two reviewers also screened for other relevant articles from 2002 to 2004. Case reports, review articles, technical studies, and single surgeon case series were excluded. Results: For several questions, high quality randomized clinical trials had been completed. Carotid endarterectomy reduces the stroke risk compared to medical therapy alone for patients with 70 to 99% symptomatic stenosis (16% absolute risk reduction at 5 years). There is a smaller benefit for patients with 50 to 69% symptomatic stenosis (absolute risk reduction 4.6% at 5 years). There is a small benefit for asymptomatic patients with 60 to 99% stenosis if the perioperative complication rate is low. Aspirin in a dose of 81 to 325 mg per day is preferred vs higher doses (650 to 1,300 mg per day) in patients undergoing endarterectomy. Conclusions: Evidence supports carotid endarterectomy for severe (70 to 99%) symptomatic stenosis (Level A). Endarterectomy is moderately useful for symptomatic patients with 50 to 69% stenosis (Level B) and not indicated for symptomatic patients with <50% stenosis (Level A). For asymptomatic patients with 60 to 99% stenosis, the benefit/risk ratio is smaller compared to symptomatic patients and individual decisions must be made. Endarterectomy can reduce the future stroke rate if the perioperative stroke/death rate is kept low (<3%) (Level A). Low dose aspirin (81 to 325 mg) is preferred for patients before and after carotid endarterectomy to reduce the rate of stroke, myocardial infarction, and death (Level A).

Changes in Plasma Homocyst(e)ine in the Acute Phase After Stroke

Background and Purpose—; Elevated plasma homocyst(e)ine [H(e)] concentration has been associated with an increased risk of stroke. Although the literature suggests that H(e) increases from the acute to the convalescent phase after a stroke, it is not known whether H(e) changes within the acute period. Methods—; A prospective, multicenter study was conducted to examine changes in H(e) during the 2 weeks after an incident stroke. Blood samples were collected at days 1, 3, 5, 7, and between 10 and 14 days after the stroke. Results—; Seventy-six participants (51 men) were enrolled from 9 sites from February 1997 through June 1998. Mean age was 65.6 years, and subjects had at least two H(e) measurements. The estimated mean H(e) level at baseline was 11.3±0.5 &mgr;mol/L, which increased consistently to a mean of 12.0±0.05, 12.4±0.5, 13.3±0.5, and 13.7±0.7 &mgr;mol/L at days 3, 5, 7, and 10 to 14, respectively. The magnitude of the change in H(e) was not affected by age, sex, smoking status, alcohol use, history of hypertension or diabetes, or Rankin Scale Score. Conclusions—; These data suggest that the clinical interpretation of H(e) after stroke and the eligibility for clinical trials assessing treatment for elevated H(e) levels require an adjustment in time since stroke to properly interpret the observed H(e) levels.

Death associated with asymptomatic carotid artery stenosis: Long-term clinical evaluation

PURPOSE As part of a prospective clinical trial on the efficacy of carotid endarterectomy in patients with asymptomatic carotid artery stenosis, we studied the risk factors for death in 444 male patients. METHODS At entry to the trial, patients were judged to be healthy enough to be randomized to operative intervention and were judged to be free of any disease that would preclude a minimal 5-year life expectancy after randomization. RESULTS Patients were treated with aspirin and optimal medical care and were monitored for an average of 4 years. Combined mortality rate was 37% (9% per year) for the medical group (38%) and surgical group (35%). Eight factors were identified that were significantly associated with increased mortality rates: coronary artery disease (p = 0.044), history of angina (p = 0.047), congestive heart failure (CHF) (p = 0.012), abnormal electrocardiography results at entry (p = 0.005), peripheral vascular disease (p = 0.019), claudication (p = 0.044), diabetes (p = 0.008), and history of hypertension (p = 0.044). The increase in risk indicated by the odds ratios (OR) were moderate (OR < 2.00) for each of the clinical risk factors except for CHF. Sixteen of 27 patients (59%) with a history of CHF at entry to the study died during follow-up (OR = 2.67). Arteriographic predictors of increased mortality rates included bilateral carotid artery stenosis and intracranial vascular disease (ICVD). With bilateral stenosis, 42% (80 of 190 patients) died compared with 33% (83 of 252 patients) with unilateral stenosis (p = 0.062). With ICVD, 43% (56 of 130 patients) died compared with 34% (107 of 314 patients) of those without ICVD (p = 0.073). Multivariate analysis demonstrated that three risk factors were significantly associated with an increased risk of death: diabetes, abnormal electrocardiography results, and claudication. Patients with two or three of these risk factors demonstrated annual mortality rates of 11.3% and 13%, respectively. This was significantly higher than patients with none of these risks (OR = 2.95 and OR = 4.06, respectively). CONCLUSION Adult male patients with high-grade asymptomatic carotid artery stenosis demonstrate a mortality rate of 37% at a mean follow-up of 4 years. Although age was not a risk for increased mortality rates in this population, diabetes, abnormal electrocardiography results, and claudication were significant. Patients with two or three of these risk factors were at high risk of death and may require aggressive treatment of their concurrent medical diseases.

Withdrawal of warfarin prior to a surgical procedure: time to follow the guidelines?

Background and Objective: Patients with cardiogenic sources of embolism may be at increased risk of cerebral infarction when anticoagulation therapy is suspended for surgical procedures. The purpose of this study was to determine frequency of cardioembolic cerebral infarction during periprocedural warfarin withdrawal. Methods: Retrospective analysis of prospective cerebral infarction registry data from two tertiary medical centers. Results: Over a 12-month period, 14 cases of cardioembolic cerebral infarction occurring during the period of warfarin withdrawal for a medical procedure were observed, accounting for 7.1% of the 197 cardioembolic cerebral infarctions encountered. Across all patients, cerebral infarctions developed an average of 5.4 days after the last dose of warfarin (range 3–8). Among the 14 patients (8 males and 6 females) with warfarin cessation-related infarcts, age ranged from 54 to 91 years. Each had been on chronic anticoagulation with warfarin for more than 1 year. Retrospective analysis suggested that all these cerebral infarctions had been potentially preventable. In each case, either the planned procedure did not require discontinuation of warfarin or, when withdrawal was required, no bridging, parenteral anticoagulation was provided to lessen the risk during the warfarin-free period. Conclusion: Patients at high risk of cardioembolic cerebral infarction may benefit from more intensive management strategies to reduce cerebral infarction risk during periprocedural periods.

Serial Urinary 11-Dehydrothromboxane B2, Aspirin Dose, and Vascular Events in Blacks After Recent Cerebral Infarction

Background and Purpose— Incomplete platelet inhibition by aspirin (aspirin resistance) may be a reason for stroke recurrence in some patients. 11-Dehydrothromboxane B2 (11-DTB2) is a stable thromboxane A2 metabolite that reflects in vivo platelet activation. This pilot study was intended to evaluate the reproducibility of urinary 11-DTB2 over time and to look for evidence of aspirin resistance. Methods— All subjects were screened for the African American Antiplatelet Stroke Prevention Study (AAASPS) 7 to 90 days after noncardioembolic cerebral infarction. Of 83 subjects with at least 1 urine sample, 52 were enrolled in AAASPS (randomized to blinded treatment with aspirin 650 mg/d or ticlopidine 500 mg/d), and 31 were enrolled in an open-label antiplatelet therapy cohort. Subjects were followed up for 2 years, with 11-DTB2 measurements scheduled at baseline and 6, 12, and 24 months. Vascular events were cerebral infarction, myocardial infarction, or vascular death. Results— Despite considerable individual up or down fluctuations, the median 11-DTB2 change did not significantly differ from zero in any of the subgroups. However, in 6 subjects with a 4-fold decrease in aspirin dose from 1300 to 325 or 81 mg/d, the 11-DTB2 level increased from 611 to 1881 pg/mg creatinine (P =0.06). Vascular events occurred in 7 of 61 aspirin-treated subjects, and 11-DTB2 levels did not correlate with the events. Conclusions— Fluctuations in urinary 11-DTB2 after cerebral infarction in blacks do not correlate with changes in aspirin doses, except perhaps when the dose changes by a factor of 4 or more. A larger study is needed to look further for aspirin resistance.

Midbrain Ataxia: Possible Role of the Pedunculopontine Nucleus in Human Locomotion

Midbrain lesions have rarely been implicated as a responsible location in patients presenting with gait instability. In animals, stimulation of the pontomesencephalic area results in rapid walking followed by running. Ablative lesions in this area cause a reduction of locomotor activity [1]. However, the center in humans is probably more dependent upon cortical and subcortical input to activate the system. We report a case of a 66-year-old male who had a subacute infarction in the left posterior tegmentum presenting primarily with gait instability, further supporting the evidence that brainstem locomotor regions also exist in humans.

Comparison of Secondary Prevention Care after Myocardial Infarction and Stroke

Background: Whether secondary prevention of atherosclerosis is performed as frequently after cerebrovascular events (stroke or transient ischemic attack) as after cardiac events (myocardial infarction or angina) is unknown. Methods: We compared the receipt of six secondary preventive care processes among 943 persons with a prior cardiac event to that among 523 persons with a prior cerebrovascular event using a representative sample of the US population. Results: The cardiac event group had higher rates for three care processes: antithrombotic medication use in the past year (83–77%, p = 0.01), ever advised to exercise more (66–52%, p < 0.001), and ever advised to eat fewer high-fat or high-cholesterol foods (70–54%, p < 0.001). Conclusions: Compared to the cardiac event group, the quality of care of the cerebrovascular event group is lower and should be improved.

Preventing stroke: a review of current guidelines.

Stroke is the third leading cause of death in the United States and is a major cause of disability. It is now estimated that there are more than 700,000 incidents of strokes annually and 4.4 million stroke survivors living with neurologic sequelae of varying severity. The economic burden of stroke, including both direct and indirect costs, was estimated by the American Heart Association to be

Use of antithrombotic agents among U.S. stroke survivors, 2000-2006.

51 billion in 1999. Epidemiologic data suggest a substantial leveling off of prior declines in stroke-related mortality and a possible increase in stroke incidence within the last decade, stressing the necessity for further efforts to reduce the burden of this disease. Despite some advances in treatment of acute ischemic stroke, prevention remains the cornerstone for managing stroke. Persons with a low level of risk factors have lifelong low levels of both heart disease and stroke (Table 1). Stroke-prone individuals can be identified and targeted for specific interventions for modification of risk factors for ischemic stroke. NONMODIFIABLE RISK FACTORS