What medical regimen is recommended for this patient with symptomatic ICAD?
Dual Antiplatelet Therapy
DAT with aspirin and clopidogrel is thought to reduce ischemic events related to regional thromboembolism. The best clinical evidence of the use of DAT in symptomatic ICAD is found in outcomes data for the SAMMPRIS trial where 30-day recurrent ischemic stroke rates in the aggressive medical management arm were significantly lower than patients treated with aspirin or warfarin monotherapy as part of the Warfarin and Aspirin for Symptomatic Intracranial Arterial Stenosis (WASID) trial. A subgroup of patients enrolled in WASID with similar clinical characteristics to those in SAMMPRIS were found to have a 30-day rate of stroke or death of 10.7% and a collective 1-year rate of ischemic stroke, brain hemorrhage, or vascular death of 25% [2]. The corresponding rates in the SAMMPRIS medical management arm were 5.8% at 30 days and 17.5% at 1 year. Given that the recurrent stroke rates were significantly lower in as little as 30 days, these benefits have been hypothesized to be more likely secondary to the DAT regimen than other risk factor modification [7]. There is some evidence that longer term DAT with aspirin and clopidogrel up to 1 year may be associated with further reduction in stroke, MI, and vascular death with similar bleeding risk, but this needs to be evaluated in prospective studies [8].
Additional evidence of the benefit and potential mechanism from DAT in ICAD comes from CLAIR (Clopidogrel plus Aspirin versus Aspirin alone for Reducing Embolization in Patients with Acute Symptomatic Cerebral or Carotid Artery Stenosis Trial), a multicenter, randomized trial with blinded outcome assessment, with patients recruited at sites in Hong Kong, Singapore, China, Thailand, and Malaysia [9]. Patients were enrolled with an extracranial or intracranial stenosis (greater than or equal to 50%, as diagnosed by carotid duplex, transcranial Doppler, or magnetic resonance angiography) if they had a clinical diagnosis of acute ischemic stroke or transient ischemic attack (TIA) during the 7 days prior to enrollment and were found to have microembolic signals (suggesting microemboli of atherosclerotic origin) detected at baseline assessment with transcranial Doppler ultrasound. Patients were randomized to DAT with aspirin and clopidogrel versus aspirin monotherapy. Patients on DAT had significantly reduced microembolic signals compared with patients on aspirin monotherapy. Asymptomatic embolization with dual antiplatelet therapy may also proffer a reduction in clinical events in these patients with symptomatic ICAD.