Neurocognitive function following out-of-hospital cardiac arrest: A systematic review

Cardiac arrest and cardiopulmonary resuscitation outcome reports: 2024 update of the Utstein Out-of-Hospital Cardiac Arrest Registry template

The Utstein Out-of-Hospital Cardiac Arrest Resuscitation Registry Template, introduced in 1991 and updated in 2004 and 2015, standardizes data collection to enable research, evaluation, and comparisons of systems of care. The impetus for the current update stemmed from significant advances in the field and insights from registry development and regional comparisons. This 2024 update involved representatives of the International Liaison Committee on Resuscitation and used a modified Delphi process. Every 2015 Utstein data element was reviewed for relevance, priority (core or supplemental), and improvement. New variables were proposed and refined. All changes were voted on for inclusion. The 2015 domains-system, dispatch, patient, process, and outcomes-were retained. Further clarity is provided for the definitions of out-of-hospital cardiac arrest attended resuscitation and attempted resuscitation. Changes reflect advancements in dispatch, early response systems, and resuscitation care, as well as the importance of prehospital outcomes. Time intervals such as emergency medical service response time now emphasize precise reporting of the times used. New flowcharts aid the reporting of system effectiveness for patients with an attempted resuscitation and system efficacy for the Utstein comparator group. Recognizing the varying capacities of emergency systems globally, the writing group provided a minimal dataset for settings with developing emergency medical systems. Supplementary variables are considered useful for research purposes. These revisions aim to elevate data collection and reporting transparency by registries and researchers and to advance international comparisons and collaborations. The overarching objective remains the improvement of outcomes for patients with out-of-hospital cardiac arrest.

Evaluating neurocognitive outcomes in out-of-hospital cardiac arrest survivors: A comparative study of performance-based and reported measures

AIMS

To (1) describe the prevalence of cognitive dysfunctions using performance-based and reported measures, and (2) explore the correlations between selected performance-based, patient-reported, and observer-reported neurocognitive outcome measures three months after hospital discharge in a population of out-of-hospital cardiac arrest (OHCA) survivors.

METHODS

Data from 193 OHCA survivors was derived from the Danish multicenter REVIVAL cohort study. At three months, four subtests of the performance-based Delis-Kaplan Executive Function System (D-KEFS) (Trail making, Color-word interference, Verbal fluency, and Figure design), the patient-reported Behavior Rating Inventory of Executive Function - Adult (BRIEF-A), and the observer-reported 16-item Short Form (SF) Informant Questionnaire on Cognitive Decline after Cardiac Arrest (SF-16 IQCODE-CA) were collected. Spearman's rank coefficient correlation analysis was performed to examine correlations between D-KEFS, BRIEF-A, and SF-16 IQCODE-CA.

RESULTS

Overall, 21% of survivors exhibited impairment in executive functioning using the D-KEFS subtest Color-word interference, while only 9% self-reported executive impairment (BRIEF-A) and 7% of relatives reported cognitive decline (SF-16 IQCODE-CA) in survivors at three months post-arrest. All correlations between D-KEFS, BRIEF-A and SF-16 IQCODE-CA were negligible to low.

CONCLUSION

The results of this REVIVAL substudy suggest that although the performance-based and reported measures did not correlate, dual neurocognitive screening tools containing both a self-reported and an informant-reported version may have the potential to detect executive discrepancies in the return to everyday life and guide targeted neurorehabilitation after OHCA.

Brain network changes and cognitive function after cardiac arrest

Survival rates after out-of-hospital cardiac arrest have improved over the past two decades. Despite this progress, long-term cognitive impairment remains prevalent even in those with early recovery of consciousness after out-of-hospital cardiac arrest; however, little is known about the determinants and underlying mechanisms. We utilized the REcovery after cardiac arrest surVIVAL cohort of out-of-hospital cardiac arrest survivors who fully regained consciousness to correlate cognition measurements with brain network changes using resting-state functional MRI and the Montreal Cognitive Assessment at hospital discharge and a comprehensive neuropsychological assessment at three-month follow-up. About half of out-of-hospital cardiac arrest survivors displayed cognitive impairments at discharge, and in most, cognitive deficits persisted at three-month follow-up, particularly in the executive and visuospatial functions. Compared to healthy controls, out-of-hospital cardiac arrest survivors exhibited increased connectivity between resting-state networks, particularly involving the frontoparietal network. The increased connectivity between the frontoparietal and visual networks was associated with less favourable cognitive outcomes (β = 14.0, P = 0.01), while higher education seemed to confer some cognitive protection (β = -2.06, P = 0.03). In sum, the data highlight the importance of subtle cognitive impairment, also in out-of-hospital cardiac arrest survivors who are eligible for home discharge, and the potential of functional MRI to identify alterations in brain networks correlating with cognitive outcomes.

The experiences of cardiac arrest survivors and their key supporters following cardiac arrest: A systematic review and meta-ethnography

AIM

To review qualitative studies on the experience of sudden cardiac arrest survival from the perspective of both survivors and their key supporters, including family/close friends.

METHODS

A seven-step meta-ethnography and synthesis of qualitative evidence was undertaken, informed by the Meta-Ethnography Reporting Guidelines (eMERGe). Four major databases were searched (Medline, EMBASE, CINAHL, PsycINFO; January 1995-January 2022, updated July 2023) for qualitative studies exploring survivors' and/or key supporters' experiences of cardiac arrest survival. The Critical Appraisal Skills Programme checklist and Grading of Recommendations Assessment, Development and Evaluation - Confidence in Evidence from Reviews of Qualitative Research (GRADE-CERQual) were applied to evaluate the overall confidence in research findings. Constructs were identified from each paper, informing theme and sub-theme development.

RESULTS

From 15,917 unique titles/abstracts and 196 full-text articles, 32 met the inclusion criteria. Three themes captured the survivors' experiences: 1) Making sense of my cardiac arrest; 2) Learning to trust my body and mind; and 3) Re-evaluating my life. A further three themes reflected key supporters' experiences: 1) Emotional turmoil; 2) Becoming a carer: same person but different me; and 3) Engaging with a new and unknown world. However, limited data and some methodological weaknesses in included studies reduced confidence in several themes. The findings were conceived within the overarching concept of 'negotiating a new normal'.

CONCLUSIONS

The enduring psychosocial and physical sequelae of cardiac arrest survival substantially impacts the lives of survivors and their key supporters, requiring negotiation of their 'new normality'. The need for sense-making, physical and psychological recovery, and the new roles for key supporters should be strong considerations in the development of future interventions.

Intranasal Administration of Mesenchymal Stem Cell-Derived Exosome Alleviates Hypoxic-Ischemic Brain Injury

Hypoxic-ischemic brain injury arises from inadequate oxygen delivery to the brain, commonly occurring following cardiac arrest, which lacks effective treatments. Recent studies have demonstrated the therapeutic potential of exosomes released from mesenchymal stem cells. Given the challenge of systemic dilution associated with intravenous administration, intranasal delivery has emerged as a promising approach. In this study, we investigate the effects of intranasally administered exosomes in an animal model. Exosomes were isolated from the cell supernatants using the ultracentrifugation method. Brain injury was induced in Sprague-Dawley rats through a transient four-vessel occlusion model. Intranasal administration was conducted with 3 × 108 exosome particles in 20 µL of PBS or PBS alone, administered daily for 7 days post-injury. Long-term cognitive behavioral assessments, biodistribution of exosomes, and histological evaluations of apoptosis and neuroinflammation were conducted. Exosomes were primarily detected in the olfactory bulb one hour after intranasal administration, subsequently distributing to the striatum and midbrain. Rats treated with exosomes exhibited substantial improvement in cognitive function up to 28 days after the insult, and demonstrated significantly fewer apoptotic cells along with higher neuronal cell survival in the hippocampus. Exosomes were found to be taken up by microglia, leading to a decrease in the expression of cytotoxic inflammatory markers.

The ROCK trial-a multidisciplinary Rehabilitation intervention for sudden Out-of-hospital Cardiac arrest survivors focusing on return-to-worK: a pragmatic randomized controlled trial protocol

INTRODUCTION

Most cardiac arrest survivors are classified with mild to moderate cognitive impairment; roughly, 50% experience long-term neurocognitive impairment. Postarrest challenges complicate participation in society and are associated with social issues such as failure to resume social activities and impaired return to work. The effectiveness of rehabilitation interventions for out-of-hospital cardiac arrest survivors are sparsely described, but the body of evidence describes high probabilities of survivors not returning to work, returning to jobs with modified job descriptions, returning to part-time employment, and often in combination with extensive unmet rehabilitation needs. Hence, there is a need to develop and test a pragmatic individual targeted intervention to facilitate return to work (RTW) in survivors of OHCA. The overall aim of the ROCK trial is to evaluate the effectiveness of a comprehensive individually tailored multidisciplinary rehabilitation intervention for survivors of OHCA on RTW compared to usual care.

METHODS AND ANALYSIS

The ROCK trial is a two-arm parallel group multicentre investigator-initiated pragmatic randomized controlled superiority trial with primary endpoint measured 12 months after the cardiac arrest. Adult survivors who were part of the labour force prior to the OCHA and had at least 2 years until they are qualified to receive retirement state pensions are eligible for inclusion. Survivors will be randomized 1:1 to usual care group or usual care plus a comprehensive tailored rehabilitation intervention focusing on supporting RTW. After comprehensive assessment of individual rehabilitation needs, the intervention is ongoingly coordinated within a multidisciplinary rehabilitation team, and the intervention can be delivered for up until 12 months. Data for the primary outcome will be obtained from the national register on social transfer payments. The primary outcome will be analysed using logistic regression assessing RTW status at 12 months adjusting for the intervention and age at OHCA, sex, marital status, and occupation prior to OHCA.

DISCUSSION

The ROCK trial is the first RCT to investigate the effectiveness of a rehabilitation intervention focusing on return to work after cardiac arrest.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05173740. Registered on May 2018.

Cognitive impairment and psychopathology in sudden out-of-hospital cardiac arrest survivors: Results from the REVIVAL cohort study

AIM

To investigate cognitive impairment and psychopathology in out-of-hospital cardiac arrest (OHCA) survivors using a screening procedure during hospitalisation and examine the evolution of these parameters at three-month follow-up.

METHODS

This multicentre cohort study screened for cognitive impairment using the Montreal Cognitive Assessment (MoCA), for symptoms of anxiety, depression and traumatic distress using the Hospital Anxiety and Depression Scale (HADS) and the Impact of Event Scale-revised (IES-R) during hospitalisation. At three-month follow-up, we evaluated cognitive impairment with a neuropsychological test battery and symptoms of psychopathology were re-assessed using HADS and IES-R. Logistic regression models were applied to examine associations between screening results and outcomes.

RESULTS

This study included 297 OHCA survivors. During hospitalisation, 65% presented with cognitive impairment, 25% reported symptoms of anxiety, 20% symptoms of depression and 21% symptoms of traumatic distress. At follow-up, 53% reported cognitive impairment, 17% symptoms of anxiety, 15% symptoms of depression and 19% symptoms of traumatic distress. Cognitive impairment during hospitalisation was associated with higher odds (OR (95% CI) 2.55 (1.36-4.75), p = .02) of an unfavorable cognitive outcome at follow-up, and symptoms of psychopathology during hospitalisation were associated with higher odds of psychopathology at follow-up across all three symptom groups; anxiety (6.70 (2.40-18.72), p < .001), depression (4.69 (1.69-13.02), p < .001) and traumatic distress (7.07 (2.67-18.73), p < .001).

CONCLUSION

OHCA survivors exhibited both cognitive impairment and symptoms of psychopathology during hospitalisation comparable to previous studies, which were associated with unfavorable mental health outcomes at three-month follow-up.

Telephone-based evaluation of cognitive impairment and mood disorders in cardiac arrest survivors with good neurologic outcomes: a retrospective cohort study

This study determined the occurrence of cognitive impairment and mood disorders in out-of-hospital cardiac arrest (OHCA) survivors with good neurologic outcomes. We performed a retrospective, cross-sectional, single-center study with a total of 97 patients. We evaluated cognitive dysfunction via the Montreal Cognitive Assessment and Alzheimer's disease-8 mood disorders via the Patient Health Questionnaire-9 and the Hospital Anxiety and Depression Scale. We measured quality of life with the European Quality of Life 5-Dimension 5-Levels questionnaire. Cognitive impairment and mood disorders were common among patients with good neurologic recovery. There were 23 patients who experienced cognitive impairments (23.7%) and 28 who suffered from mood disorders (28.9%). Age (adjusted OR 1.07, 95% CI 1.02-1.12), mood disorders (adjusted OR 22.80, 95% CI 4.84-107.49) and hospital length of stay (adjusted OR 1.05, 95% CI 1.02-1.09) were independent risk factors for cognitive impairment. The occurrence of cognitive impairments (adjusted OR 9.94, 95% CI 2.83-35.97) and non-cardiac causes of cardiac arrest (adjusted OR 11.51, 95% CI 3.15-42.15) were risk factors for mood disorders. Quality of life was significantly lower in the OHCA survivors with each disorder than the healthy individuals. Routine screening and intervention are needed for OHCA survivors.

Effects of Hypothermia vs Normothermia on Societal Participation and Cognitive Function at 6 Months in Survivors After Out-of-Hospital Cardiac Arrest: A Predefined Analysis of the TTM2 Randomized Clinical Trial

Importance

The Targeted Hypothermia vs Targeted Normothermia After Out-of-Hospital Cardiac Arrest (TTM2) trial reported no difference in mortality or poor functional outcome at 6 months after out-of-hospital cardiac arrest (OHCA). This predefined exploratory analysis provides more detailed estimation of brain dysfunction for the comparison of the 2 intervention regimens.

Objectives

To investigate the effects of targeted hypothermia vs targeted normothermia on functional outcome with focus on societal participation and cognitive function in survivors 6 months after OHCA.

Design, Setting, and Participants

This study is a predefined analysis of an international multicenter, randomized clinical trial that took place from November 2017 to January 2020 and included participants at 61 hospitals in 14 countries. A structured follow-up for survivors performed at 6 months was by masked outcome assessors. The last follow-up took place in October 2020. Participants included 1861 adult (older than 18 years) patients with OHCA who were comatose at hospital admission. At 6 months, 939 of 1861 were alive and invited to a follow-up, of which 103 of 939 declined or were missing.

Interventions

Randomization 1:1 to temperature control with targeted hypothermia at 33 °C or targeted normothermia and early treatment of fever (37.8 °C or higher).

Main outcomes and measures

Functional outcome focusing on societal participation assessed by the Glasgow Outcome Scale Extended ([GOSE] 1 to 8) and cognitive function assessed by the Montreal Cognitive Assessment ([MoCA] 0 to 30) and the Symbol Digit Modalities Test ([SDMT] z scores). Higher scores represent better outcomes.

Results

At 6 months, 836 of 939 survivors with a mean age of 60 (SD, 13) (range, 18 to 88) years (700 of 836 male [84%]) participated in the follow-up. There were no differences between the 2 intervention groups in functional outcome focusing on societal participation (GOSE score, odds ratio, 0.91; 95% CI, 0.71-1.17; P = .46) or in cognitive function by MoCA (mean difference, 0.36; 95% CI,-0.33 to 1.05; P = .37) and SDMT (mean difference, 0.06; 95% CI,-0.16 to 0.27; P = .62). Limitations in societal participation (GOSE score less than 7) were common regardless of intervention (hypothermia, 178 of 415 [43%]; normothermia, 168 of 419 [40%]). Cognitive impairment was identified in 353 of 599 survivors (59%).

Conclusions

In this predefined analysis of comatose patients after OHCA, hypothermia did not lead to better functional outcome assessed with a focus on societal participation and cognitive function than management with normothermia. At 6 months, many survivors had not regained their pre-arrest activities and roles, and mild cognitive dysfunction was common.

Trial Registration

ClinicalTrials.gov Identifier: NCT02908308.

Life satisfaction in cardiac arrest survivors: A nationwide Swedish registry study

Introduction

Most cardiac arrest (CA) survivors report good health and quality of life. Life satisfaction on the other hand has not yet been studied in a large scale in the CA population. We aimed to explore life satisfaction as perceived by CA survivors with three research questions addressed: (1) how do CA survivors report their life satisfaction, (2) how are different domains of life satisfaction associated with overall life satisfaction, and (3) how are demographic and medical factors associated with overall life satisfaction?

Methods

This registry study had a cross-sectional design. Life satisfaction was assessed using the 11-item Life Satisfaction checklist (LiSat-11). The sample included 1435 survivors ≥18 years of age. Descriptive statistics and binary logistic regression analyses were used.

Results

Survivors were most satisfied with partner relation (85.6%), family life (82.2%), and self-care (77.8%), while 60.5% were satisfied with overall life. Satisfaction with psychological health was strongest associated with overall life satisfaction. Among medical and demographic factors, female sex and poor cerebral performance were associated with less overall life satisfaction.

Conclusions

Generally, CA survivors seem to perceive similar levels of overall life satisfaction as general populations, while survivors tend to be significantly less satisfied with their sexual life. Satisfaction with psychological health is of special interest to identify and treat. Additionally, female survivors and survivors with poor neurological outcome are at risk for poorer overall life satisfaction and need special attention by healthcare professionals.

Is insomnia associated with self-reported health and life satisfaction in cardiac arrest survivors? A cross-sectional survey

Background

Insomnia symptoms seem to be common in cardiac arrest survivors but their associations with important outcomes such as self-reported health and life satisfaction have not previously been reported during the early post-event period. Therefore, the aim of the study was to investigate whether symptoms of insomnia are associated with self-reported health and life satisfaction in cardiac arrest survivors six months after the event.

Methods

This multicentre cross-sectional survey included cardiac arrest survivors ≥18 years. Participants were recruited six months after the event from five hospitals in southern Sweden, and completed a questionnaire including the Minimal Insomnia Symptom Scale, EQ-5D-5L, Health Index, Hospital Anxiety and Depression Scale, and Satisfaction With Life Scale. Data were analysed using the Mann-Whitney U test, linear regression, and ordinal logistic regression. The regression analyses were adjusted for demographic and medical factors.

Results

In total, 212 survivors, 76.4% males, with a mean age of 66.6 years (SD = 11.9) were included, and of those, 20% reported clinical insomnia. Insomnia was significantly associated with all aspects of self-reported health (p < 0.01) and life satisfaction (p < 0.001), except mobility (p = 0.093), self-care (p = 0.676), and usual activities (p = 0.073).

Conclusion

Insomnia plays a potentially important role for both health and life satisfaction in cardiac arrest survivors. Screening for sleep problems should be part of post cardiac arrest care and follow-up to identify those in need of further medical examination and treatment.

Neuropsychological outcome after cardiac arrest: results from a sub-study of the targeted hypothermia versus targeted normothermia after out-of-hospital cardiac arrest (TTM2) trial

BACKGROUND

Cognitive impairment is common following out-of-hospital cardiac arrest (OHCA), but the nature of the impairment is poorly understood. Our objective was to describe cognitive impairment in OHCA survivors, with the hypothesis that OHCA survivors would perform significantly worse on neuropsychological tests of cognition than controls with acute myocardial infarction (MI). Another aim was to investigate the relationship between cognitive performance and the associated factors of emotional problems, fatigue, insomnia, and cardiovascular risk factors following OHCA.

METHODS

This was a prospective case-control sub-study of The Targeted Hypothermia versus Targeted Normothermia after Out-of-Hospital Cardiac Arrest (TTM2) trial. Eight of 61 TTM2-sites in Sweden, Denmark, and the United Kingdom included adults with OHCA of presumed cardiac or unknown cause. A matched non-arrest control group with acute MI was recruited. At approximately 7 months post-event, we administered an extensive neuropsychological test battery and questionnaires on anxiety, depression, fatigue, and insomnia, and collected information on the cardiovascular risk factors hypertension and diabetes.

RESULTS

Of 184 eligible OHCA survivors, 108 were included, with 92 MI controls enrolled. Amongst OHCA survivors, 29% performed z-score ≤ - 1 (at least borderline-mild impairment) in ≥ 2 cognitive domains, 14% performed z-score ≤ - 2 (major impairment) in ≥ 1 cognitive domain while 54% performed without impairment in any domain. Impairment was most pronounced in episodic memory, executive functions, and processing speed. OHCA survivors performed significantly worse than MI controls in episodic memory (mean difference, MD = - 0.37, 95% confidence intervals [- 0.61, - 0.12]), verbal (MD = - 0.34 [- 0.62, - 0.07]), and visual/constructive functions (MD = - 0.26 [- 0.47, - 0.04]) on linear regressions adjusted for educational attainment and sex. When additionally adjusting for anxiety, depression, fatigue, insomnia, hypertension, and diabetes, executive functions (MD = - 0.44 [- 0.82, - 0.06]) were also worse following OHCA. Diabetes, symptoms of anxiety, depression, and fatigue were significantly associated with worse cognitive performance.

CONCLUSIONS

In our study population, cognitive impairment was generally mild following OHCA. OHCA survivors performed worse than MI controls in 3 of 6 domains. These results support current guidelines that a post-OHCA follow-up service should screen for cognitive impairment, emotional problems, and fatigue.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03543371. Registered 1 June 2018.

The aftermath of surviving a sudden cardiac arrest for young exercisers - a qualitative study in Norway

BACKGROUND

When surviving a sudden cardiac arrest (SCA), physical, cognitive, and emotional effects of surviving may be present for months or years. The survivors' family and colleagues are also highly affected by the incident. There is little knowledge about experiences of surviving SCA in individuals who prior to the incident were young and reported to exercise regularly. Consequently, the aim of this study was to explore the aftermath of surviving a SCA in young, regular exercisers.

METHODS

The study had a qualitative design, conducting in-depth individual interviews with SCA survivors < 50 years of age reporting to exercise ≥ 5 h/week and/or who suffered SCA during or less than 60 min after exercise. The data were analysed using systematic text condensation in-line with recommendations from Malterud.

RESULTS

18 of 31 eligible participants were included in the study. Through analysis we identified 'Establishing a new everyday life' as superordinate category, with subordinate categories a) being part of my surroundings, b) expecting normality but facing a new reality and c) lucky to be alive!

CONCLUSION

This study adds knowledge about young and regular exercisers' experiences after surviving a SCA. The obligations of everyday life in young survivors of SCA often imply a high work load and complex tasks, e.g. due to being in the beginning of their career or even still studying. Healthcare personnel, as well as the society, need to acknowledge that although lucky to be alive and apparently well-functioning, young survivors of SCA may have persistent challenges that cause frustration and reduced quality of life.

The Montreal Cognitive Assessment is a valid Cognitive Screening Tool for Cardiac Arrest Survivors

AIM

The survival rate of out-of-hospital cardiac arrest (OHCA) patients has increased over the past decades. This gives rise to a growing number of patients with hypoxic-ischemic brain damage and cognitive impairment. Currently, cognitive impairment is underdiagnosed in OHCA patients. There is a need for a validated cognitive screening instrument to identify patients with cognitive impairment. This study aimed to examine the diagnostic value of the Montreal Cognitive Assessment (MoCA) in patients after OHCA.

METHODS

Survivors (age ≥18 years) of OHCA completed the MoCA and a gold standard neuropsychological test battery, including tests for memory, attention, perception, language, reasoning, and executive functioning, at around one year after OHCA. Results of the MoCA are related to the results of the neuropsychological test battery. Analyses of diagnostic accuracy included receiver operating characteristics and calculation of predictive values.

RESULTS

We included 54 OHCA survivors (mean age = 57.3, 74% male). The area under the curve (AUC) was 0.8, 95% CI [0.67, 0.93]. The MoCA showed excellent sensitivity of 86%, 95% CI [57, 98] and adequate specificity of 70.0%, 95% CI [53, 83] to detect cognitive impairment at the regular cut-off score of 26. The positive predictive value of the MoCA was 50%, 95% CI [30, 70] and the negative predictive value was 93%, 95% CI [76, 99].

CONCLUSION

This study shows that the MoCA may be a valid cognitive screening instrument for use in the OHCA patient population.