Frailty and Cognitive Function Assessment of TAVI Patients (The Hungarian Frailty Score) - Observational, Prospective, Singe Center Study

Aortic stenosis (AS) is the most common valve disease among the adult population, in the majority of the cases it only requires treatment in advanced age. Surgical aortic valve replacement (SAVR) is very often refused because of advanced age and poor general condition. These patients used to receive only medical treatment which is less favorable compared to SAVR. Nowadays transcatheter aortic valve implantation (TAVI) has become available as an alternative treatment for very high risk or even inoperable patients who are suffering from symptomatic aortic stenosis (1). Between 2012 and 2014 TAVI has been used extensively, accumulating over 100,000 procedures performed worldwide since 2002 (2). TAVI was originally developed for those patients who were considered too frail to undergo SAVR (3). Recently, we are able to perform TAVI in almost all patients with high procedure success rate and achieve good hemodynamic results. Despite these promising results, the one year outcome is not so evident. Until now it has been learnt that there are a group of patients who are in a very bad condition and who are so frail that they do not benefit from TAVI. These patients have worse survival rate and more importantly poor quality of life in spite of a successful procedure. Cardiac surgery risk scores like Society of Thoracic surgery score (STS) and EUROSCORE are less accurate in aging high risk people (4). Advanced age is often accompanied with frail general conditions and, the estimated morbidity and mortality values do not correlate well with the postoperative outcomes. In these risk scores very important relevant factors like frailty and disability are not taken into account. In elderly it is principal to make differentiation between utility and futility. Frailty is a clinical syndrome that reflects impaired physiologic reserve and increased vulnerability to stressors (5). However frailty as a geriatric concept has existed for a long time, its importance has recently gained high priority in the concept of older adults especially who undergo TAVI(1). By today frailty scores have increasing importance and are used more frequently by several investigators. Slow 5m gait speed has evidently proven unfavorable outcomes (6, 7), other frailty assessment tools like handgrip strength test, activities of daily living (ADL), instrumental activities of daily living (iADL), nutritional assessment, mini-mental status, etc. has been being investigated continuously.

On the other hand, beside frailty status the main barrier to TAVI is the risk of neurological impairment. The TAVI candidate patients have specific central nervous system (CNS) issues because of neurobiological changes of aging, e.g. decreased brain weight and volume, decreased neurotransmitter system function, decreased neuronal gene expression and Alzheimer type changes (8). Neurological injury and impairment in TAVI can occur as cerebrovascular event (CVE) and/or neurocognitive dysfunction. Both forms might be clinically apparent and detected, clinically apparent but undetected and clinically silent and undetected. The two neurocognitive dysfunctions - post-operative delirium (POD) and post-operative cognitive dysfunction (POCD) - most cases remain undetected although clinically could be apparent or silent (9). POD is defined by Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). POCD is defined by Kappetein et al., as "deterioration of intellectual function presenting as impaired memory or concentration presenting with temporal association to surgery" (9, 10). The neurological injury can be observed and/or detected by neuroimaging techniques and cognitive trajectories. Some insult caused by TAVI might remain in the clinically silent area and might be observed only as slight neurocognitive dysfunction. Analization of the incidence and underlying etiology of the neurological events may lead to identification of recently non-recognized techniques or neuroprotective strategies, devices. The most elevated incidence of CVEs is within 24 hours of TAVI. This risk of further events might be high for up to two months (11). One fifth of health-related quality of life (HRQOL) is characterized by cognitive functions. Studies and reports on cognitive, psychiatric, and/or neurological events following TAVI have focused on major and well-marked complications, e.g., stroke, TIA, and post-operative delirium (12). Meantime TAVI is associated with a high incidence (73%-84%) of silent cerebral embolism as detected by diffusion-weighted MRI (13).

Chronological age does not always reflect biological age and there is a wide range between fit to frail (14). A well established and validated frailty score based on relatively simple and feasible tests could help in our everyday practice to evaluate the prognosis of elderly people undergoing TAVI and to determine those patients who really benefit from the procedure. Post-Operative Cognitive Dysfunction (POCD) in patients undergoing TAVI (and/or SAVR) was examined in only a few studies published during the last 10 years. Examinations and investigation of finer, long-term and possibly positive post-operative cognitive outcomes following TAVI (and SAVR) are significantly under-represented in the current medical literature (15).

Hypothesis:

There is a significant correlation between the Hungarian Frailty Score (HFS) and post procedure outcomes and quality of life preservation. HFS score would be a useful tool to estimate those who will benefit from TAVI. We also hypothesize that cognitive performance will be preserved, and will improve at the end of 12th month after TAVI due to better cerebral circulation.