Background Little is known about mental health following advanced cardiac procedures in the oldest patients. Aims To study changes in anxiety and depression from baseline to one- and six-month follow-up in older patients following transcatheter aortic valve implantation (TAVI) or surgical aortic valve replacement (SAVR). Methods Prospective cohort study of patients >= 80 years undergoing elective TAVI or SAVR in a tertiary university hospital. Anxiety and depression were assessed with the Hospital Anxiety and Depression Scale. Differences between TAVI/SAVR were analyzed using Welch's t test or chi-squared. Changes over time and group differences were established with longitudinal models using generalized least squares. Results In 143 patients (83.5 +/- 2.7 years), 46% (n = 65) received TAVI. Anxiety was identified in 11% of TAVI patients at baseline. One- and six-months later, percentages were 8% and 9%. In SAVR patients, 18% had baseline scores indicating anxiety. One and six-months later, percentages were 11% and 9%. Depression was identified in 15% of TAVI patients. One- and six-months later, percentages were 11% and 17%. At baseline, 11% of SAVR patients had scores indicating depression. One- and six-months after SAVR, percentages were 15% and 12%. Longitudinal analyses showed reductions (P < 0.001) in anxiety from baseline to one-month, and stable scores between one- and six-months for both treatment groups. There was no change over time for depression among treatment groups (P = 0.21). Discussion and conclusions SAVR or TAVI in patients >= 80 years was associated with anxiety reduction between baseline and follow-up. For depression, there was no evidence of change over time in either treatment group.