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.