The Carotid and Middle Cerebral Artery Occlusion Surgery Study
Condition: Carotid Artery Occlusion; Middle Cerebral Artery Occlusion; Stroke
MeSH terms: Infarction, Middle Cerebral Artery; Arterial Occlusive Diseases
Study type: Interventional
Phase: Phase 3

Summary: 
      The recently published Carotid Occlusion Surgery Study (COSS) failed to show a benefit of
      extracranial-intracranial (EC-IC) bypass surgery over medical therapy in patients with
      symptomatic hemodynamically significant carotid occlusion. Since then on, different
      controversies have been raised on several aspects including the study population,
      qualifications of surgeons and hemodynamic evaluation.

      In COSS protocol, the primary inclusion population is the patient demonstrating occlusion of
      unilateral ICA while the contralateral ICA less than 50% stenosis. Because of the enrollment
      problems, in the final result report, 18% patients suffered from contralateral ICA stenosis
      more than 50%. As we known, COSS utilized oxygen extraction fraction (OEF) ratio by PET as
      the criterion of hemodynamic evaluation. Bilateral ICAs lesion will disturbed the ratio even
      the identifying the subgroup of patients with hemodynamic insufficiency.

      As an interventional trial, the COSS should ensure the certification for the experienced
      surgeons. While for expanding the number of centers and enhancing recruitment, COSS made some
      concessions on the surgeons training and certification. The 15% postoperative event rate is
      not the best that can be achieved according to recent surgical technical development.

      The cerebral hemodynamic insufficiency has been considered as the primary pathophysiological
      factor for patients with ICA or MCA occlusion. For these patients, antiplatelet therapy is
      not likely to prevent hemodynamic stroke.EC-IC bypass surgery probably will be the possible
      effective therapy.

      These underlying assumptions deserved further exploration and more strict research.So the
      CMOSS study in China is designed to compare the efficacy and safety of EC-IC bypass surgery
      with medical therapy in patients with symptomatic hemodynamically significant carotid
      occlusion.
    

Detailed description: 
      Patients with symptoms of cerebral or retinal ischemia associated with ipsilateral internal
      carotid artery (ICA) occlusion have an annual risk of 5-8% of recurrent ischemic stroke.
      While in China, the incidence of middle cerebral artery (MCA) occlusion is higher than in
      western countries. The annual risk of recurrent ischemic stroke in patients with symptomatic
      ICA or MCA occlusion has not improved over the years. The proportion of recurrence that was
      minor disabling was rather high.
    

Intervention name(s): bypass surgery; Aspirin; Clopidogrel
Intervention type(s): Procedure; Drug; Drug
Intervention description(s): all participants in this group will be performed EC-IC bypass surgery; all participants in this group will be given medical therapy including Aspirin 100mg per day or clopidogrel 75mg per day
Other intervention name(s): EC-IC bypass surgery; Aspirin 100mg per day or clopidogrel 75mg per day
Intervention MeSH terms: Aspirin; Clopidogrel
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: carotid artery occlusion; middle cerebral artery occlusion; EC-IC bypass surgery; stroke