Delirium after Aortic Valve Therapy. A Prospective Cohort Study of Octogenarian Patients following Surgical Aortic Valve Replacement and Transcatheter Aortic Valve Implantation.

Abstract

Introduction: Untreated and symptomatic aortic stenosis (AS) is associated with high mortality. Surgical aortic valve replacement (SAVR) and transcatheter aortic valve implantation (TAVI) are two treatment options for patients with severe AS. Patients receiving SAVR and TAVI are often 80 years and older. Delirium, an acute state of confusion characterized by temporary and fluctuating decline in attention and cognition, is common in older patients after cardiac surgery. Yet, knowledge about octogenarians undergoing invasive cardiovascular therapy is scarce, and delirium after TAVI remains to be systematically explored. Aims: The overall aim of this study was to investigate delirium in octogenarian patients undergoing SAVR or TAVI by determining its incidence, identifying risk factors, describing its onset and time course, and by determining if delirium can be used to predict physical and cognitive function, self-reported health status, first-time hospital readmissions and mortality 1 and 6 months after aortic valve treatment. Materials and Methods: This is a prospective cohort study of octogenarian patients with AS, scheduled for elective treatment with SAVR or TAVI at a tertiary university hospital in western Norway. Delirium was the main outcome of the study. Inclusion criteria were: age 80 years-old and older and previous acceptance for treatment with SAVR or TAVI. Exclusion criteria were: denied consent to participate in the study and inability to speak Norwegian. Between 2011 and 2013, 143 patients were included in the study. Demographic and clinical information was collected from hospital information system registers, patients’ medical records or by interviewing included patients, as appropriate. Delirium was assessed for 5 postoperative days with the Confusion Assessment Method. Activities of daily living, instrumental activities of daily living and self-reported health status were measured with the Barthel Index, the Nottingham Extended Activities of Daily Living Scale (IADL) and The 12-Item Short Form Health Survey (SF-12), at baseline and at 1 and 6-month follow-up. Cognitive status was assessed at baseline and at 6-month follow-up with the Mini-Mental State Examination (MMSE). Results: The mean age of included patients was 83.5 years (SD 2.7) and TAVI was performed in 46% of them. Patients undergoing SAVR had a higher incidence of delirium than patients treated with TAVI (66% vs 44%, p = 0.01). Multivariate logistic regression analysis revealed that reduced cognitive function at baseline (p = 0.03) and treatment with SAVR (p = 0.02) are risk factors for delirium in octogenarian patients after aorta valve treatment. No differences in the number of days with delirium were found between patient groups (p = 0.20) but the onset and course of delirium in patients treated with SAVR was more unpredictable (p = 0.003) than it was in patients treated with TAVI (Paper I). Patients with and without delirium after SAVR had lower IADL function at 1-month follow-up (scores from 58 to 42 and from 58 to 50 respectively p ≤ 0.02). However, this function returned to baseline levels after 6 months. Improvements in the Physical Component Summary score of SF-12 were found in patients not having delirium and treated with SAVR (from 39 to 48, p < 0.001). No differences between patient groups in other outcomes were identified. Regression models suggest that delirium after SAVR might predict IADL scores1-month after treatment (not significant, p-values ≤ 0.07) but does not predict large differences in ADL, cognitive function or SF-12 scores in octogenarian AS patients. Patients experiencing delirium after TAVI had a lower ADL (from 19 to 16, p < 0.001) and IADL function (from 49 to 40, p = 0.003) 1 month after the procedure. In TAVI patients without delirium, the physical component score of SF-12 increased after 1 and 6 months (30 to 35, p = 0.04 and 30 to 35, p = 0.02 respectively). Regression analyses established that delirium following TAVI predicted lower ADL and IADL function at 1 but not at 6-month follow-up (Paper II). First-time readmissions and death 1 and 6 months after SAVR or TAVI were more common in octogenarian patients who experienced delirium. The effect of delirium was greatest during the first two months after discharge (adjusted hazard ratio 2.9 (95% CI: 1.5 to 5.7).The most common discharge diagnosis at readmission was related to the circulatory system (Paper III). Conclusions: Delirium is often present after aortic valve treatment, especially in patients receiving SAVR. In addition to be a risk factor for delirium in octogenarian patients, SAVR was associated with a more unpredictable onset and course of delirium. Patients who experienced delirium, regardless treatment type, appear to have lower short-term IADL function. Yet, delirium does not seem to confer long-term reductions in physical, mental or self-reported health status in this patient group. Compared to patients without delirium, first-time readmissions and mortality were more common 6 months after hospital discharge in patients who had experienced delirium. Our study provides additional evidence showing that delirium is a serious hospital complication that could be associated with negative outcomes such as lower physical function, morbidity and mortality 1 and 6 months after aortic valve treatment, also when more gentle techniques like TAVI are used. These findings are also relevant when designing future studies and implementing strategies that could lead to the prevention of delirium in other older patient populations.