About this study
We aim to determine whether cognitive impairment attributable to cerebral hemodynamic impairment in patients with high-grade asymptomatic carotid artery stenosis is reversible with restoration of flow. To accomplish this aim CREST-H will add on to the NINDS-sponsored CREST-2 trial (parallel, outcome-blinded Phase 3 clinical trials for patients with asymptomatic high-grade carotid artery stenosis which will compare carotid endarterectomy plus intensive medical management (IMM) versus IMM alone (n=1,240), and carotid artery stenting plus IMM versus IMM alone (n=1,240) to prevent stroke and death). CREST-H addresses the intriguing question of whether cognitive impairment can be reversed when it arises from abnormal cerebral hemodynamic perfusion in a hemodynamically impaired subset of the CREST-2 -randomized patients. We will enroll 500 patients from CREST-2, all of whom receive cognitive assessments at baseline and yearly thereafter. We anticipate identifying 100 patients with hemodynamic impairment as measured by an inter-hemispheral MRI perfusion "time to peak" (TTP) delay on the side of stenosis. Among those who are found to be hemodynamically impaired and have baseline cognitive impairment, the cognitive batteries at baseline and at 1 year will determine if those with flow failure who are randomized to a revascularization arm in CREST-2 will have better cognitive outcomes than those in the medical-only arm compared with this treatment difference for those who have no flow failure. We hypothesize that hemodynamically significant "asymptomatic" carotid disease may represent one of the few examples of treatable causes of cognitive impairment. If cognitive decline can be reversed in these patients, then we will have established a new indication for carotid revascularization independent of the risk of recurrent stroke.