Increased Risk of Recurrent Stroke in Symptomatic Large Vessel Disease With Impaired BOLD Cerebrovascular Reactivity.

Background: Impaired cerebrovascular reactivity (CVR) has been correlated with recurrent ischemic stroke. However, for clinical purposes, most CVR techniques are rather complex, time-consuming, and lack validation for quantitative measurements. The recent adaptation of a standardized hypercapnic stimulus in combination with a blood-oxygenation-level-dependent (BOLD) magnetic resonance imaging signal as a surrogate for cerebral blood flow offers a potential universally comparable CVR assessment. We investigated the association between impaired BOLD-CVR and risk for recurrent ischemic events.
Methods: We conducted a retrospective analysis of patients with symptomatic cerebrovascular large vessel disease who had undergone a prospective hypercapnic-challenged BOLD-CVR protocol at a single tertiary stroke referral center between June 2014 and April 2020. These patients were followed up for recurrent acute ischemic events for up to 3 years. BOLD-CVR (%BOLD signal change per mm Hg CO ₂ ) was calculated on a voxel-by-voxel basis. Impaired BOLD-CVR of the affected (ipsilateral to the vascular pathology) hemisphere was defined as an average BOLD-CVR, falling 2 SD below the mean BOLD-CVR of the right hemisphere in a healthy age-matched reference cohort (n=20). Using a multivariate Cox proportional hazards model, the association between impaired BOLD-CVR and ischemic stroke recurrence was assessed and Kaplan-Meier survival curves to visualize the acute ischemic stroke event rate.
Results: Of 130 eligible patients, 28 experienced recurrent strokes (median, 85 days, interquartile range, 5-166 days). Risk factors associated with an increased recurrent stroke rate included impaired BOLD-CVR, a history of atrial fibrillation, and heart insufficiency. After adjusting for sex, age group, and atrial fibrillation, impaired BOLD-CVR exhibited a hazard ratio of 10.73 (95% CI, 4.14-27.81; P <0.001) for recurrent ischemic stroke.
Conclusions: Among patients with symptomatic cerebrovascular large vessel disease, those exhibiting impaired BOLD-CVR in the affected hemisphere had a 10.7-fold higher risk of recurrent ischemic stroke events compared with individuals with nonimpaired BOLD-CVR.
Competing Interests: Disclosures The device used in this study was developed by Thornhill Medical, Inc (TMI) a for-profit spin-off from the University Health Network, University of Toronto, to enable cerebrovascular reactivity studies. It is not a commercial product and is made available to academic centers for certified research under ethics board approval. Drs Fisher and Mikulis are appointees at the University of Toronto and employees of, and own shares in, TMI. Dr Katant is a consultant for AstraZeneca and Brahms GmbH, and receives funding from Bayer Healthcare, both of which are not related to the current article. Currently, Dr Katant has a dual appointment at the University Hospital of Zürich and the University Hospital Basel. Dr Wegener receives funding through the following institutes: Baugarten Stiftung, the Betty and David Koetser Foundation, Hartmann Müller-Stiftung für Medizinische Forschung, and the Swiss National Science Foundation and is the co-applicant of the UZH CRPP Stroke of the University Hospital of Zürich. Dr Luft is a consultant for Amgen, Boehringer Ingelheim, and Moleac Ltd. Dr Kulcsár is a consultant for Johnson and Johnson International, Medtronic, and Stryker. The other authors report no conflicts.