Abstract Background Cognitive impairment is prevalent in one third of patients with symptomatic severe aortic valve stenosis scheduled for transcatheter aortic valve implantation (TAVI). How TAVI affects cognitive functioning in these patients remains unknown. Purpose The CAPITA study (CArdiac outPut, cerebral blood flow and cognition In patients with severe aortic valve stenosis undergoing Transcatheter Aortic valve implantation) assessed the effects of TAVI on cerebral lesions and cognitive functioning. Methods CAPITA is a prospective study of cerebral and cognitive outcomes in 148 patients undergoing TAVI. One day before and three months after TAVI, patients underwent a standardized multidomain neuropsychological assessment, and simultaneous brain magnetic resonance imaging. The primary outcome was change in global cognitive functioning as measured with z-scores. Also, we assessed the cognitive subdomains of attention/psychomotor speed, memory, language, and executive functioning. Z-scores for each cognitive domain were constructed as: (test score - mean baseline score) / standard deviation. Global cognitive function was calculated as the mean from the four domain scores. Results Mean age was 80.5±5.7 years, 43% was female and median STS-PROM (Society for Thoracic Surgeons Predicted Risk for 30-day Mortality) was 2.0% (IQR 1.4%-2.9%). MoCA scores improved from 23.3±3.7 to 24.4±3.3, (p<0.001) and MMSE scores from 26.4±2.6 to 26.9±2.4 (p=0.01). There was an overall increase in global cognitive z-scores (0.02±0.52 to 0.15±0.48, p<0.001). Cognitive domains of memory (0.03±0.77 to 0.18±0.80, p=0.003) and language (-0.07±1.07 to 0.20±0.80, p=0.02) significantly improved, whereas executive function (0.01±0.70 to 0.06±0.76, p=0.42) and attention (0.10±0.69 to 0.17±0.69, p=0.06) did not significantly change. Quality of life on the visual analogue scale improved from 66.4±15.9 to 72.9±12.8, (p<0.001). Patients in the lowest tertile of baseline cognitive functioning (i.e., those with worst baseline cognitive functioning), had the largest increase in cognitive functioning, compared with patients in the intermediate or highest tertile of baseline cognitive functioning (0.30±0.55 vs 0.09±0.27 vs 0.01±0.16, p=0.002). Patients with >0.5 SD decline in cognitive functioning (12%), had a higher volume of new white matter hyperintensities on follow-up MRI than patients with stable or improved cognitive functioning (1.26±2.96, vs 0.29±0.45 vs 0.31±0.91 mL, p=0.06). Conclusions In 148 patients who underwent TAVI, there was an overall improvement in cognitive functioning at three months follow-up. This improvement was consistent through different cognitive domains and most prominent in patient with lowest baseline cognitive functioning.Change in cognitive functionin