Postoperative cognitive decline (POCD) has a perceivable influence on daily living and is noticed more often by close relatives than by patients themselves 3 months after aortic valve replacement. This study aimed to elucidate the longitudinal course of the subjective awareness of POCD.Follow-up of a prospective observational study.A single cardiothoracic center in Germany.The study included 108 patients scheduled for elective aortic valve replacement surgery and 85 close relatives of the patients.In addition to conducting a neuropsychologic examination, the authors previously interviewed 82 patients with a Cognitive Failure Questionnaire for self-assessment (s-CFQ), and 62 relatives with the Cognitive Failure Questionnaire for others (f-CFQ) before and 3 months after surgery. Up until 12 months after surgery, the authors continuously interviewed additional patients (baseline and 3 months after surgery), thereby enlarging the original sample, and included the entire group (108 patients, 85 relatives) for the 12-month follow-up.The analysis showed that relatives (p = 0.026) and patients experienced patients' cognitive decline 3 months after surgery (p = 0.009). All changes still were observed in questions related to memory and attention. After 1 year, the s-CFQ no longer differed between baseline and postoperative assessment. Mean scores in the f-CFQ still were above baseline, barely missing statistical significance (p = 0.051). In patients with "change to worse" in the f-CFQ at 1-year follow-up, declining cognitive results in nonverbal learning (p = 0.021) could be observed 3 months postoperatively. Only a decrease in 3-month f-CFQ correlated with a decline in specific neuropsychologic tests 3 months after surgery.Contrary to the authors' previous results, the impact of POCD on daily living functions also was recognized by the patients themselves. The long-term influence and the associations between subjective deficits and psychometric cognitive measures seemed to be assessed more reliably by close relatives.