Objectives: The authors sought to determine baseline neurocognition before transcatheter aortic valve replacement (TAVR) and its correlations with pre-TAVR brain imaging. Background: TAVR studies have not shown a correlation between diffusion-weighted image changes and neurocognition. The authors wanted to determine the extent to which there was already impairment at baseline that correlated with cerebrovascular disease. Methods: SENTINEL (Cerebral Protection in Transcatheter Aortic Valve Replacement) trial patients had cognitive assessments of attention, processing speed, executive function, and verbal and visual memory. Z-scores were based on normative means and SDs, combined into a primary composite z-score. Brain magnetic resonance images were obtained pre-TAVR on 3-T scanners with a T2 fluid-attenuated inversion recovery (FLAIR) sequence. Scores ≤−1.5 SD below the normative mean (7th percentile) were considered impairment. Paired t tests compared within-subject scores, and chi-square goodness-of-fit compared the percentage of subjects below −1.5 SD. Correlation and regression analyses assessed the relationship between neurocognitive z-scores and T2 lesion volume. Results: Among 234 patients tested, the mean composite z-score was −0.65 SD below the normative mean. Domain scores ranged from −0.15 SD for attention to −1.32 SD for executive function. On the basis of the ≥1.5 SD normative reference, there were significantly greater percentages of impaired scores in the composite z-score (13.2%; p = 0.019), executive function (41.9%; p < 0.001), verbal memory (p < 0.001), and visual memory (p < 0.001). The regression model between FLAIR lesion volume and baseline cognition showed statistically significant negative correlations. Conclusions: There was a significant proportion of aortic stenosis patients with impaired cognition before TAVR, with a relationship between baseline cognitive function and lesion burden likely attributable to longstanding cerebrovascular disease. These findings underscore the importance of pre-interventional testing and magnetic resonance imaging in any research investigating post-surgical cognitive outcomes in patients with cardiovascular disease.