Severe aortic stenosis is the most common valvular heart disease in the elderly in the Western world and contributes to a large proportion of all deaths over the age of 70. Severe aortic stenosis is conventionally treated with surgical aortic valve replacement; however, the less invasive transcatheter aortic valve implantation (TAVI) is suggested for those at high surgical risk. While TAVI has been associated with improved survival and favourable outcomes, there is a higher incidence of cerebral microembolisms in TAVI patients. This finding is of concern given mechanistic links with cognitive decline, a symptom highly prevalent in those with cardiovascular disease. This paper reviews the literature assessing the possible link between TAVI and cognitive changes. Studies to date have shown that global cognition improves or remains unchanged over 3 months following TAVI while individual cognitive domains remain preserved over time. However, the association between TAVI and cognition remains unclear due to methodological limitations. Furthermore, while these studies have largely focused on memory, cognitive impairment in this population may be predominantly of vascular origin. Therefore, cognitive assessment focusing on domains important in vascular cognitive impairment, such as executive dysfunction, may be more helpful in elucidating the association between TAVI and cognition in the long term.
Cardiovascular disease including valvular heart disease contributes to an estimated 36% of all deaths over the age of 70 [
Recent evidence from randomized controlled trials suggests an increased risk of neurological events for up to one year after TAVI in comparison to surgical aortic valve replacement and medical treatment [
Methodology recommended by the PRISMA guidelines for systematic reviews was followed for all analyses [
Search criteria returned 568 unique records of cognitive assessments in patients undergoing TAVI (Figure
Summary of studies measuring global cognition after TAVI using the MMSE.
Study |
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Type of TAVI | Baseline | After procedure | 1-month F/U | 3-month F/U |
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Orvin et al., 2014 [ |
36 | TF (MCV) = 31 |
25.9 ± 3.3 | — | 27.6 ± 2.4 |
— |
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Ghanem et al., 2013 [ |
111 | TF (MCV) = 95 |
25.4 ± 3.4 | 25.4 ± 3.3a |
— | — |
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Kahlert et al., 2012 [ |
83 |
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27.9 |
27.7 |
— | 28.3 |
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— |
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— |
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— |
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Knipp et al., 2013 [ |
27 | TA (ES) = 27 |
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— |
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Rodés-Cabau et al., 2011 [ |
60 | TF (ES) = 29 |
28 |
28 |
— | — |
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Kahlert et al., 2010 [ |
32 | TF (MCV) = 10 | 28.9 |
28.0 |
— | 28.9 |
TF (ES) = 22 | 28.1 |
28.3 |
28.1 |
All studies were observational prospective cohort study.
aSubgroup with no risk of cognitive decline.
bSubgroup with risk of cognitive decline.
cChange in
Illustration of search strategy.
Characteristics of the 349 patients in the eligible studies, including demographics, surgical risk scores, cognitive status, comorbidities, and prevalence of cardiovascular risk factors, are shown in Table
Summary of TAVI patient population characteristics at baseline in current studies.
Parameter | Orvin et al., 2014 [ |
Ghanem et al., 2013 [ |
Kahlert et al., 2012 [ |
Knipp et al., 2013 [ |
Rodés-Cabau et al., 2011 [ |
Kahlert et al., 2010 [ | |
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36 | 111 | 83 | 27 | 60 | 22 (ES) | 10 (MCV) |
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Demographics | |||||||
Age, mean ± SD | 82.2 ± 4.2 | 80 ± 6 | 80.6 (79.3–81.8) | 82.2 ± 4.7 | 83 ± 7 | 78.3 (76.4–80.2) | 83.8 (79.2–88.4) |
Male gender, % ( |
52.8 (19) | 54 (60) | 57.8% (35) | 74.1 (20) | 50 (30) | 36 (14) | 60 (4) |
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Risk scores | |||||||
Logistic EuroSCORE, mean ± SD | 14.9 ± 11.4 | 24.3 ± 14.7 | 20.7 (17.8–23.5) | 36.4 ± 13.2 | 18.9 ± 12.8 | 22.8 (16.5–29.2) | 17.9 (12.0–23.7) |
Society of Thoracic Surgeons Score | 7.4 ± 4.1 | 8.5 ± 5.4 | 6.7 (5.7–7.7) | — | 7.7 ± 4.6 | — | — |
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Cognitive status | |||||||
Mini-mental status exam, mean ± SD | 25.9 ± 3.3 | 25.4 ± 3.4 | 27.9 (27.5–28.3) | — | 28 (17–30) | 28.9 (28.2–29.6) | 28.1 (26.7–29.5) |
Mild cognitive impairment, % ( |
— | 27 (30) | — | — | — | — | — |
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Comorbidities | |||||||
Coronary artery disease, % ( |
— | 63 (71) | 55.4 (46) | 55.5 (15) | 73 (44) | 64 (14) | 50 (5) |
Renal dysfunction, % ( |
30.5 (11) | — | 16.9 (14) | — | 88 (53)a | 32 (7) | 10 (1) |
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Cardiovascular risk factors | |||||||
Obesity, % ( |
— | — | 50.6 (42) | — | 88 (53) | 41 (9) | 0 (0) |
Smoking, % ( |
— | 18 (20) | 21.7 (18) | 29.6 (8) | 2 (1) | 23 (5) | 20 (2) |
Diabetes, % ( |
30.5 (11) | 31 (35) | 30.1 (25) | 29.6 (8) | 25 (15) | 27 (6) | 40 (4) |
Hypertension, % ( |
88.9 (32) | 98 (109) | 97.6 (81) | 100 (27) | 75 (45) | 95 (21) | 90 (9) |
Dyslipidemia, % ( |
83.3 (30) | 81 (90) | 72.3 (60) | 74.1 (20) | 73 (44) | 86 (19) | 50 (5) |
aRenal dysfunction indicated by estimated glomerular filtration rate <60 mL/min.
The MMSE is a widely used screening tool for cognitive impairment where a score equal to or below 24 can be indicative of cognitive impairment [
Of the three studies that followed TAVI patients over a period of 3 months, two showed a significant improvement in MMSE scores after TAVI [
Knipp et al. performed the first study to determine changes in specific cognitive domains in patients undergoing TAVI using a cognitive battery [
Ghanem et al. used a cognitive battery to assess neuropsychological outcomes over 2 years after TAVI [
Orvin et al. also assessed cognitive function in patients undergoing TAVI using the quantitative clock drawing test, colors trails tests (CTT1 and CTT2), and Cognistat before and one month after TAVI [
Studies assessing cognition following TAVI have generally found cognitive improvement or preservation. Specifically, global cognition significantly improved or remained unchanged while changes in individual cognitive domains remained unchanged for up to 2 years following TAVI. These findings are consistent with recent meta-analyses, which found improvements in processing speed, executive function, verbal short-term memory, and working memory up to 1 year after coronary artery bypass graft surgery [
Improvements in cognition after cardiovascular surgery such as TAVI may be attributed to significant changes in hemodynamic parameters, particularly cardiac output [
Alleviation of physical symptoms and subsequent improvement in functional status may also contribute to improvements in cognition after TAVI. It is known that patients with severe aortic stenosis experience a high degree of fatigue due to reduced ejection fraction [
Despite the favourable hemodynamic improvements following TAVI, it is important to note that patients with severe aortic stenosis are at an increased risk of cognitive impairment due to advanced age and high comorbidity burden. More specifically, patients with severe aortic stenosis have a high prevalence of coronary artery disease and typically present with multiple vascular risk factors (Table
All 6 studies measured global cognitive function before and after TAVI using the MMSE as a measure of cognitive decline. It is of interest to note that studies reported significant increase in MMSE scores following TAVI even though more sensitive and specific measures of cognition did not appear to change. It is possible that improvements in MMSE scores may be due to learning effects [
Studies assessing cognitive changes in specific domains following TAVI may also not have effectively assessed vascular cognitive impairment, particularly executive function. In the study by Ghanem et al. [
Mechanisms underlying cognitive changes after TAVI are unclear. It was hypothesized that a high incidence of cerebral microembolisms associated with both vascular dementia and Alzheimer’s disease [
To date, there have been 4 studies that have performed DW-MRI to detect microembolic lesions and concurrently measured cognitive function [
Summary of studies utilizing DW-MRI to view cerebral ischemia and assessed global cognition using the MMSE.
Study |
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Type of TAVI | Time after TAVI that DW-MRI was performed | Number of patients with lesions | Incidence of patients with lesions | Total number of lesions | Average number of lesions per patient |
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Ghanem et al., 2013 [ |
111 | TF (MCV) = 95 |
3 days | 36a | 64% | — | — |
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Knipp et al., 2013 [ |
27 | TA (ES) = 27 | 10.7 ± 4.9 days | 12 | 58% | 22 | 1.83 |
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Rodés-Cabau et al., 2011 [ |
60 | TF (ES) = 29 |
4 ± 1 days | 19 |
66% |
83 |
4.37 |
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Kahlert et al., 2010 [ |
32 | TF (MCV) = 10 |
3.4 days (2.5–4.4) | 8 |
80% |
26 |
3.25 |
aOnly 56 patients were able to undergo postprocedural imaging.
This review was limited by a heterogeneous patient population as indicated by wide variability in logistic EuroSCOREs at baseline. Follow-up times varying in length from 3 days to 3 months and different cognitive assessments used made it difficult to compare data. Furthermore, cerebrovascular disease was reported inconsistently and neither carotid nor cerebrovascular disease was accounted for in the analyses. Practice effects may have contributed to the lack of change or improvement in cognition. The lack of control groups, short duration of follow-up, and small sample sizes also make it difficult to make concrete conclusions.
TAVI is becoming an increasingly popular alternative to surgical aortic valve replacement as the procedure improves survival, is less invasive, and can be performed in high-risk patients with severe aortic stenosis. Studies have generally shown no change or cognitive improvement after TAVI possibly due to beneficial improvements in hemodynamic status. Cognitive preservation or improvement after TAVI in a population with a declining cognitive trajectory already set in motion by aging and significant underlying vascular disease may suggest benefit. The balance between positive changes associated with TAVI and already existing predisposing factors is currently obscured by various limitations in these studies. Larger prospective longitudinal studies are needed to validate current findings using a more comprehensive battery to assess vascular cognitive impairment in order to clearly elucidate the association between TAVI and cognition.
The authors report no pertinent conflict of interests.