Outcome measures. The primary outcome measure is the evidence of new ischemic lesions on the 48-hour DWI relative to pre-operative DWI. In addition, the following outcome measures will be considered in exploratory analyses: 1) Any new ischemic lesion on 30 day DWI or FLAIR relative to pre-op DWI or FLAIR; 2) Evidence of clinically definite ischemic stroke (focal neurological deficits persisting for more than 24 hours) confirmed by non-investigational CT or MRI (if protocol-required scans are not obtained) occurring within the first 30 days (plus or minus 3 days) after surgery; 3) All cause mortality; 4) Encephalopathy; 5) Cognitive decline at 30 days; 6) Cognitive decline at 6 months; 7) Evidence of reperfusion injury on 48-hour post-gadolinium FLAIR; 8) New ischemic lesions on 6-month DWI or FLAIR; 9) Changes in values of blood markers; 10) Number, volume, and location of new DWI or FLAIR lesions.