Risk of disease progression in patients with moderate asymptomatic carotid artery stenosis: implications of tobacco use and dual antiplatelet therapy

Abstract

Background: Because of improved medical therapy in contemporary practice, some have advocated that, most if not, all patients with asymptomatic carotid disease should be managed medically without intervention. Disease progression in this patient population is not well established, and data describing risk factors for disease progression in patients with moderate asymptomatic carotid artery stenosis (ASCAS) are lacking. The aim of our study was to determine the incidence of and risk factors for disease progression in this patient population.

Methods: All patients presenting to a tertiary center between January 2005 and May 2012 with moderate (50-69%) ASCAS as determined by carotid artery duplex were included. Outcomes including disease progression to severe stenosis (≥70%), incidence of symptoms, need for operative intervention, and all-cause mortality were recorded. Cox proportional hazard regression models were used to identify risk factors for disease progression.

Results: A total of 282 carotid arteries in 258 patients with moderate ASCAS were identified from 1555 carotid duplex scans over the 7.5-year study period (mean age: 70.6 ± 0.55 years, 52% male). Mean follow-up time was 2.6 ± 0.10 years. Overall, disease progression to severe stenosis occurred in 25.2% (n = 71) and followed a linear trend. The incidence of symptoms including ipsilateral stroke (2.13%, n = 6) and transient ischemic attack (0.71%; n = 2) was low. Carotid endarterectomy was performed in 15.3% (n = 43) of patients, all with severe disease. Carotid stenting was performed in 3.90% (n = 11) patients. Risk of progression was higher in patients receiving dual antiplatelet therapy (Hazard Ratio [HR] 1.85, 95% confidence interval [CI] 1.09-3.15; P = 0.02) and smokers (HR 1.85, 95% CI 0.96-3.55; P = 0.05). Age, gender (women), hypertension, statin use, and aspirin use were not significant predictors of progression to severe stenosis. There was a nonsignificant trend toward increased mortality in patients who progressed compared with those who did not (HR 3.39, 95% CI 0.91-12.6; P = 0.07).

Conclusions: In our study, one-quarter of patients with moderate ASCAS progressed to severe disease, although the majority remained asymptomatic. Smoking and dual antiplatelet therapy are independent risk factors for disease progression. Patients with identifiable risk factors may warrant more careful follow-up.