The Carotid and Middle Cerebral Artery Occlusion Surgery Study
Status:
Active, not recruiting
Trial end date:
2020-09-01
Target enrollment:
Participant gender:
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.