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.
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.
- Clopidogrel (Plavix®)Drug
Other Names: Plavix ARM 1: Kind: Experimental Label: medical group Description: all the participants in this group will be given medical therapy including aspirin 100mg per day or clopidogrel 75mg per day
- Aspirin Drug
Other Names: clopidogrel; combination aspirin-dipyridamole Intervention Desc: all participants in this group will be given medical therapy including Aspirin 100mg per day or clopidogrel 75mg per day ARM 1: Kind: Experimental Label: medical group Description: all the participants in this group will be given medical therapy including aspirin 100mg per day or clopidogrel 75mg per day
- Bypass surgery Procedure
Other Names: EC-IC bypass surgery Intervention Desc: all participants in this group will be performed EC-IC bypass surgery ARM 1: Kind: Experimental Label: bypass group Description: all the participants in this group will be performed EC-IC bypass surgery
- Allocation: Randomized
- Masking: Single Blind (Outcomes Assessor)
- Purpose: Treatment
- Endpoint: Safety/Efficacy Study
- Intervention: Parallel Assignment
|Type||Measure||Time Frame||Safety Issue|
|Primary||the number of participants who suffer from stroke or death after EC-IC bypass surgery or medical therapy||up to 30 days||Yes|
|Primary||the number of participants who suffer from ipsilateral ischemic stroke||up to 24 months||No|
|Secondary||the number of participants who suffer from severe transit ischemic attack (TIA)||up to 24 months of randomization||No|
|Secondary||the number of participants who suffer from all stroke or death during 30 days to 24 months||during 30 days to 24 months||No|
|Secondary||the changes from baseline in mRS, national institutes of health stroke scale (NIHSS) and Barthel Index||at 7 days, 30 days, 6 months, 12 months and 24 months||No|
|Secondary||the changes from baseline of cerebral blood flow (CBF) ratio in CT perfusion||at 24 months||No|
|Secondary||the number of participants who suffer from all kinds of adverse events related to surgery||up to 30 days||Yes|