Clinical short communication| Volume 425, 117450, June 15, 2021

Clopidogrel underactivity is a common in patients with acute symptomatic severe carotid stenosis

Published:April 14, 2021DOI:


      • Clopidogrel underactivity prevalence in acute symptomatic carotid patients is unknown.
      • Clopidogrel reactivity was measured at the beginning of endovascular procedure
      • 35 patients were included and 12 showed clopidogrel underactivity.
      • More severe carotid stenosis was seen in clopidogrel underactivity patients.
      • % stenosis was associated with clopidogrel underactivity on multivariate analysis



      Clopidogrel is commonly used for secondary stroke prevention in patients with large vessel stenosis. Reduced Clopidogrel high on treatment platelet reactivity (CR) can lead to Clopidogrel underactivity (CU) causing acute thrombosis. However, the prevalence of CU among patients with acute symptomatic carotid disease remains unknown. Therefore, we aimed to find the prevalence and identify the predictors for CU among patients with acutely symptomatic carotid stenosis.

      Patients and methods

      Over the span of 14 months, CR was measured at the time of endovascular procedure in all patients undergoing angiography and stenting because of acute symptomatic carotid stenosis. Only patients treated per institutional protocol with a combination of Clopidogrel and Aspirin were included. CR was measured with VerifyNowP2Y12 reaction units (PRU) and CU was defined as PRU > 208. Patients with CU were compared to those without CU.


      Thirty-five patients were included (mean age 71.3 ± 10, 76% men) and twelve (34.3%, mean age 71.8 ± 8.4, 58% men) had CU at the time of endovascular intervention. On univariate analysis more severe carotid stenosis was seen in CU patients (92.6 ± 6.5% vs 81.6 ± 13.6%, p = 0.013) and percent stenosis was independently associated with CU on multivariate analysis (p = 0.023).


      CU is present in 1 of every 3 patients with acutely symptomatic carotid disease. The current results suggest that CR testing should become part of routine care in patients with acutely symptomatic carotid disease.


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