Asymptomatic carotid artery disease – What is the evidence for intervention?

Strong evidence exists in favor of revascularization in symptomatic carotid artery stenosis. Contrarily, no unified consensus exits on the best management strategy in asymptomatic carotid artery disease. Early trials on carotid revascularization in asymptomatic stenosis suggested an absolute benefit in favor of intervention. However, with the advent in aggressive medical therapy, rate of stroke/TIA in the territory of asymptomatic stenosis is small and has dropped to approximately 1% per annum. Similarly, complication rate with carotid revascularization has reduced with gain in operator experience. This is evident from the lead-in phase analysis of the Carotid Revascularization Endarterectomy Versus Stenting Trial and the interim results of the asymptomatic carotid surgery (ACST) 2 trial. Therefore, it is crucial to determine the patient group at ‘high’ risk of future stroke on medical therapy. Plaque morphology, collateral status and cerebrovascular reserve, microembolic signals on Transcranial Doppler assessment, history of contralateral stroke/TIA, and severity and progression of stenosis are the key predictors of future stroke risk. We discuss the evidence in support of revascularization in severe ‘high risk’ asymptomatic stenosis based on review of published literature.