Veterans Affairs (VA) Cooperative Study Group on Asymptomatic Carotid Stenosis - VA-Asymptomatic Carotid Stenosis

Description:

Aspirin and endarterectomy for stroke in asymptomatic carotid stenosis

Hypothesis:

Aspirin and endarterectomy or endarterectomy alone may improve stroke-free survival rate in patients with asymptomatic, extracranial carotid artery stenosis

Study Design

Study Design:

Patients Screened: Not given
Patients Enrolled: 444
NYHA Class: not given
Mean Follow Up: 47.9 months
Mean Patient Age: 64.4
Female: 0
Mean Ejection Fraction: not given

Patient Populations:

Adult male patients with significant suspected carotid artery stenosis (with a diameter of the lumen reduced >50% as measured arteriographically by comparing the least transverse diameter at the point of maximal stenosis with a measured diameter of the postbulbar internal carotid artery once its diameter had become uniform)

The suspected carotid artery stenosis was confirmed by ocular pneumoplethysmography or optional duplex ultrasonography

Free of a known disease expected to limit a 5-year survival

Exclusions:

Previous endarterectomy with restenosis
Previous extracranial-intracranial bypass
High surgical risk because of associated medical illness
Previous contralateral cerebral infarction
Requiring cardiopulmonary bypass
Long-term anticoagulant therapy
Aspirin intolerance or long-term higher dose aspirin therapy
Life expectancy <5 years
Surgically inaccessible lesion
Noncompliance or refusal to participate in the protocol

Primary Endpoints:

Neurologic event, withdrawal, death, and completion of study

Drug/Procedures Used:

Aspirin, initially all patients received 650 mg bid; in 120 patients, the dose was reduced to a level of 80 to 325 mg once a day. Aspirin was discontinued in 71 patients for clinical indications.

Principal Findings:

Mortality rates in this group were not significantly different for patients not taking aspirin as compared with the rates for those taking aspirin, although patients not taking aspirin had a higher incidence of myocardial infarction (27%) as compared with patients taking aspirin (8%), p<0.05.

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).

The incidence of ipsilateral neurologic events for patients not taking aspirin as compared with that for patients who were taking aspirin, respectively, was as follows: stroke, 13.5% and 8.7%, p> 0.05; stroke and transient ischemic attack, 37.8% and 17.3%, p< 0.05.

No significant differences were observed in stroke severity scores for patients taking or not taking aspirin.

Interpretation:

These data suggest that patients with significant asymptomatic carotid artery stenosis who are intolerant of aspirin have a higher incidence of neurologic events than those patients able to tolerate the drug.

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.

References:

1. J Vasc Surg 1993;17:257-265. Influence of aspirin
2. J Vasc Surg 1993;18:1002-11. Mortality risk factors
3. New Engl J Med 1993;328:221-7. Final results

Clinical Topics: Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Prevention, Vascular Medicine, Atherosclerotic Disease (CAD/PAD), Acute Heart Failure, Interventions and Coronary Artery Disease, Interventions and Vascular Medicine, Hypertension

Keywords: Odds Ratio, Coronary Artery Disease, Myocardial Infarction, Stroke, Follow-Up Studies, Ischemic Attack, Transient, Multivariate Analysis, Endarterectomy, Carotid, Risk Factors, Electrocardiography, Constriction, Pathologic, Peripheral Vascular Diseases, Cerebrovascular Disorders, Survival Rate, Heart Failure, Carotid Stenosis, Hypertension, Diabetes Mellitus


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