Cognitive outcomes in elderly high-risk patients 1 year after off-pump versus on-pump coronary artery bypass grafting. A randomized trial

Postoperative cognitive dysfunction: a concept analysis

BACKGROUND

Post-operative cognitive dysfunction (POCD) is a concern for clinicians that often presents post-surgery where generalized anesthesia has been used. Its prevalence ranges from 36.6% in young adults to 42.4% in older individuals. Conceptual clarity for POCD is lacking in the currently body literature. Our two-fold purpose of this concept analysis was to (1) critically appraise the various definitions, while also providing the best definition, of POCD and (2) narratively synthesize the attributes, surrogate or related terms, antecedents (risk factors), and consequences of the concept.

METHOD

The reporting of our review was guided by the PRISMA statement and the 6-step evolutionary approach to concept analysis developed by Rodgers. Three databases, including Medline, CINAHL, and Web of Science, were searched to retrieve relevant literature on the concept of POCD. Two independent reviewers conducted abstract and full-text screening, data extraction, and appraisal. The review process yielded a final set of 86 eligible articles.

RESULT

POCD was defined with varying severities ranging from subtle-to-extensive cognitive changes (1) affecting single or multiple cognitive domains that manifest following major surgery (2), is transient and reversible, and (3) may last for several weeks to years. The consequences of POCD may include impaired quality of life, resulting from withdrawal from the labor force, increased patients' dependencies, cognitive decline, an elevated risk of dementia, rising healthcare costs, and eventual mortality.

CONCLUSION

This review resulted in a refined definition and comprehensive analysis of POCD that can be useful to both researchers and clinicians. Future research is needed to refine the operational definitions of POCD so that they better represent the defining attributes of the concept.

Clinically Optimal Neuropsychological Tests for Postoperative Cognitive Dysfunction in Heart Valve Surgeries

BACKGROUND

Postoperative cognitive dysfunction (POCD) is widely recognized and reported, but the lack of a uniform definition makes it difficult to evaluate its clinical impact. The aim of this study is to establish the optimal neuropsychological tests and definition of POCD relevant to clinical outcomes in heart valve surgeries.Methods and Results: Between June 2015 and December 2019, 315 patients undergoing elective heart valve surgeries (age ≥65 years) were enrolled. The Mini-Mental Status Examination, Montreal Cognitive Assessment (MoCA), and the Trail Making Test A and B were performed to evaluate cognitive function. Clinical endpoints were defined as readmission and death. The postoperative readmission and death rate were 17% and 3% (54/315 and 8/315; follow-up 266-1,889 days). By multivariable Cox hazard analysis, Short Physical Performance Battery (adjusted hazard ratio [HR]: 0.84, 95% confidence interval [CI]: 0.49-0.98, P=0.001), MoCA change rate (adjusted HR: 0.64, 95% CI: 0.01-1.22, P=0.024), and intensive care unit stay (adjusted HR: 0.55%, 95% CI: 0.99-1.12, P=0.054) were detected as independent risk factors for combined events. The cutoff value was -12% in the change rate of MoCA.

CONCLUSIONS

MoCA was the only neuropsychological test that predicted the clinical impact on complex events and has the potential to define POCD.

Potential Markers of Neurocognitive Disorders After Cardiac Surgery: A Bibliometric and Visual Analysis

Background

Identifying useful markers is essential for diagnosis and prevention of perioperative neurocognitive disorders (PNDs). Here, we attempt to understand the research basis and status, potential hotspots and trends of predictive markers associated with PNDs after cardiac surgery via bibliometric analysis.

Methods

A total of 4,609 original research articles and reviews that cited 290 articles between 2001 and 2021 were obtained from the Web of Science Core Collection (WoSCC) as the data source. We used the software CiteSpace to generate and analyze visual networks of bibliographic information, including published years and journals, collaborating institutions, co-cited references, and co-occurring keywords.

Results

The number of annual and cumulative publications from 2001 to 2021 has been increasing on the whole. The Harvard Medical School was a very prolific and important institution in this field. The journal of Ann Thorac Surg (IF 4.33) had the most publications, while New Engl J Med was the most cited journal. Neuron-specific enolase (NSE), S100b and kynurenic acid (KYNA) were frequently discussed as possible markers of PNDs in many references. Cardiopulmonary bypass (CPB) was a keyword with high frequency (430) and sigma (6.26), and inflammation was the most recent burst keyword.

Conclusion

Potential markers of PNDs has received growing attention across various disciplines for many years. The research basis mainly focuses on three classic biomarkers of S100b, NSE, and KYNA. The most active frontiers are the inflammation-related biomarkers (e.g., inflammatory cells, cytokines, or mediators) and surgery-related monitoring parameters (e.g., perfusion, oxygen saturation, and the depth of anesthesia).

Is postoperative cognitive decline after cardiac surgery associated with plasma beta amyloid 1-42 levels?

Background

Postoperative cognitive decline following cardiac surgery is one of the frequently reported complications affecting postoperative outcome, characterized by impairment of memory or concentration. The aetiology is considered multifactorial and the research conducted so far has presented contradictory results. The proposed mechanisms to explain the cognitive decline associated with cardiac surgery include the neurotoxic accumulation of β-amyloid (Aβ) proteins similar to Alzheimer's disease. The comparison of coronary artery bypass grafting procedures concerning postoperative cognitive decline and plasmatic Aβ1-42 concentrations has not yet been conducted.

Methods

The research was designed as a controlled clinical study of patients with coronary artery disease undergoing surgical myocardial revascularization with or without the use of a cardiopulmonary bypass machine. All patients completed a battery of neuropsychological tests and plasmatic Aβ1-42 concentrations were collected.

Results

The neuropsychological test results postoperatively were significantly worse in the cardiopulmonary bypass group and the patients had larger shifts in the Aβ1-42 preoperative and postoperative values than the group in which off-pump coronary artery bypass was performed.

Conclusions

The conducted research confirmed the earlier suspected association of plasmatic Aβ1-42 concentration to postoperative cognitive decline and the results further showed that there were less changes and lower concentrations in the off-pump coronary artery bypass group, which correlated to less neurocognitive decline. There is a lot of clinical contribution acquired by this research, not only in everyday decision making and using amyloid proteins as biomarkers, but also in the development and application of non-pharmacological and pharmacological neuroprotective strategies.

Cognitive Outcomes after DEXmedetomidine sedation in cardiac surgery: CODEX randomised controlled trial protocol

INTRODUCTION

Older patients undergoing cardiac surgery carry the highest risk for developing major postoperative neurocognitive disorder (postoperative NCD or P-NCD) with up to 25% incidence 3 months after surgery. P-NCD is associated with significant morbidity, mortality, loss of independence, premature retirement and increased healthcare costs. This multicentre randomised trial is investigating the efficacy of postoperative dexmedetomidine sedation in reducing the incidence of major P-NCD after cardiac surgery compared with standard protocols. CODEX will be the largest interventional trial with major P-NCD as the primary outcome.

METHODS AND ANALYSIS

CODEX is recruiting patients ≥60 years old, undergoing elective cardiac surgery and without pre-existing major cognitive dysfunction or dementia. Eligible participants are randomised to receive postoperative dexmedetomidine or standard institutional sedation protocols in the intensive care unit. Baseline preoperative cognitive function is assessed with the computer-based Cogstate Brief Battery. The primary outcome, major P-NCD, 3 months after surgery is defined as a decrease in cognitive function ≥1.96 SD below age-matched, non-operative controls. Secondary outcomes include delirium, major P-NCD at 6/12 months, depressive symptoms, mild P-NCD and quality of surgical recovery at 3/6/12 months. The specific diagnostic criteria used in this protocol are consistent with the recommendations for clinical assessment and management of NCD from the Nomenclature Consensus Working Group on perioperative cognitive changes. Intention-to-treat analysis will compare major P-NCD at 3 months between study groups.

ETHICS AND DISSEMINATION

CODEX was approved by Sunnybrook Health Sciences Centre Research Ethics Board (REB) (Project ID 1743). This will be the first multicentre, randomised controlled trial to assess the efficacy of a pharmacological intervention to reduce the incidence of major P-NCD after cardiac surgery in patients ≥60 years old. Dissemination of the study results will include briefings of key findings and interpretation, conference presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT04289142.

Frailty is highly prevalent in specific cardiovascular diseases and females, but significantly worsens prognosis in all affected patients: A systematic review

Cardiologists are more often confronted with older (>60 years) cardiovascular disease (CVD) patients. These patients have particular needs in clinical care because, for example, of frailty. However, it remains to be established what is the prevalence of frailty in different CVD's and how it relates to mortality. In this systematic review studies were included if they: (i) examined subjects (men and women) aged ≥60 years who suffered from any CVD with or without cardiac surgery, (ii.) examined the presence of frailty with a well-defined frailty tool and (iii.) reported prevalence rates of frailty. From thirty studies comprising 96.841 participants, it is found that 1. Frailty is highly common in older patients with CVD (in particular in females (approximately 1.6 times more than in males), in heart failure (up to 80 % of patients) and aortic valve disease (up to 74 % of patients)), and 2. Frailty is related to a 2.5-3.5-fold elevated mortality risk, even in patients with less severe CVD (e.g. percutaneous coronary intervention). Moreover, there is a lack of consistency on how to assess frailty as up to 20 different tools/assessment batteries are currently used. It is concluded that frailty should be assessed in all older CVD patients in a uniform manner to enhance clinical care and outcomes.

Postoperative Cognitive Dysfunction after Coronary Artery Bypass Grafting

Postoperative cognitive dysfunction is a common complication following cardiac surgery. The incidence of cognitive dysfunction is more pronounced in patients receiving a cardiac operation than in those undergoing a non-cardiac operation. Clinical observations demonstrated that pulsatile flow was superior to nonpulsatile flow, and membrane oxygenator was superior to bubble oxygenator in terms of postoperative cognitive status. Nevertheless, cognitive assessments in patients receiving an on-pump and off-pump coronary artery bypass surgery have yielded inconsistent results. The exact mechanisms of postoperative cognitive dysfunction following coronary artery bypass grafting remain uncertain. The dual effects, neuroprotective and neurotoxic, of anesthetics should be thoroughly investigated. The diagnosis should be based on a comprehensive cognitive evaluation with neuropsychiatric tests, cerebral biomarker inspections, and electroencephalographic examination. The management strategies for cognitive dysfunction can be preventive or therapeutic. The preventive strategies of modifying surgical facilities and techniques can be effective for preventing the development of postoperative cognitive dysfunction. Investigational therapies may offer novel strategies of treatments. Anesthetic preconditioning might be helpful for the improvement of this dysfunction.

RAGE antagonism by FPS‑ZM1 attenuates postoperative cognitive dysfunction through inhibition of neuroinflammation in mice

Neuroinflammation triggered by surgical trauma contributes to postoperative cognitive dysfunction (POCD). The receptor for advanced glycation end‑products (RAGE), a multiligand inflammatory receptor, is involved in the damaging effects of various cellular processes, contributing to neuroinflammation and neurodegeneration. However, the potential role of RAGE in the acute period of POCD has not been fully investigated. C57BL/6 male mice undergoing surgery of the tibia under isoflurane anesthesia were treated with the RAGE antagonist FPS‑ZM1 or vehicle control intraperitoneally for a period of 7 days. The cognitive function of the animals was tested using trace fear conditioning on the third postoperative day. To determine astrocytic activation, microgliosis, p65 expression, inflammatory factor levels and postsynaptic density protein‑95 (PSD‑95) expression in the hippocampus, the animals were euthanized on either the first, third or seventh postoperative day. Compared with the control group, the cognitive function of the surgical animals was impaired on the third postoperative day. Astrocytic activation, microgliosis and the expression levels of p65, interleukin (IL)‑1β, IL‑6, and PSD‑95 were significantly increased on the first, and third postoperative days. However, tumor necrosis factor‑α expression was significantly increased only on postoperative day 1. All of the surgical effects observed were partially inhibited by treatment with FPS‑ZM1. In summary, the results of the present study suggest that RAGE serves an important role in the acute inflammatory process of POCD, and blocking RAGE can inhibit neuroinflammation and attenuate POCD. Thus, the RAGE signaling pathway may be a novel target in the prevention, and treatment of POCD.

Neuroprotective Strategies during Cardiac Surgery with Cardiopulmonary Bypass

Aortocoronary bypass or valve surgery usually require cardiac arrest using cardioplegic solutions. Although, in principle, in a number of cases beating heart surgery (so-called off-pump technique) is possible, aortic or valve surgery or correction of congenital heart diseases mostly require cardiopulmonary arrest. During this condition, the heart-lung machine also named cardiopulmonary bypass (CPB) has to take over the circulation. It is noteworthy that the invention of a machine bypassing the heart and lungs enabled complex cardiac operations, but possible negative effects of the CPB on other organs, especially the brain, cannot be neglected. Thus, neuroprotection during CPB is still a matter of great interest. In this review, we will describe the impact of CPB on the brain and focus on pharmacological and non-pharmacological strategies to protect the brain.

Cognitive Outcomes of Cardiovascular Surgical Procedures in the Old: An Important but Neglected Area

Older individuals can now undergo invasive cardiovascular procedures without serious concern about mortality, and the numbers and proportions of the over 65s and 85s doing so in Australia has been increasing over the last 20 years. There is overwhelming evidence linking cardiovascular conditions to late-life (65 years and over) cognitive impairment and dementia including Alzheimer's Disease, primarily due to impaired cerebrovascularisation and cascading neuropathological processes. Somewhat paradoxically, these cardiovascular interventions, carried out with the primary aim of revascularisation, are not usually associated with short- or long-term improvements in cognitive function in older adults. We discuss factors associated with cognitive outcomes post-cardiovascular surgeries in patients over 65 years of age. There are many opportunities for future research: we know almost nothing about cognitive outcomes following invasive cardiac procedures in the oldest old (85 years and over) nor how to predict the cognitive/delirium outcome using pre-surgical data, and lastly, intervention opportunities exist both pre and postoperatively that have not been tested. As our population ages with increased cardiovascular burden and rates of cardiovascular interventions and surgeries, it is critical that we understand the cognitive consequences of these procedures, who is at greatest risk, and ways to optimise cognition.

Intermediate- and Long-Term Cognitive Outcomes After Cardiovascular Procedures in Older Adults: A Systematic Review

BACKGROUND

Risks for intermediate- and long-term cognitive impairment after cardiovascular procedures in older adults are poorly understood.

PURPOSE

To summarize evidence about cognitive outcomes in adults aged 65 years or older at least 3 months after coronary or carotid revascularization, cardiac valve procedures, or ablation for atrial fibrillation.

DATA SOURCES

MEDLINE, Cochrane, and Scopus databases from 1990 to January 2015; ClinicalTrials.gov; and bibliographies of reviews and eligible studies.

STUDY SELECTION

English-language trials and prospective cohort studies.

DATA EXTRACTION

One reviewer extracted data, a second checked accuracy, and 2 independently rated quality and strength of evidence (SOE).

DATA SYNTHESIS

17 trials and 4 cohort studies were included; 80% of patients were men, and mean age was 68 years. Cognitive function did not differ after the procedure between on- and off-pump coronary artery bypass grafting (CABG) (n = 6; low SOE), hypothermic and normothermic CABG (n = 3; moderate to low SOE), or CABG and medical management (n = 1; insufficient SOE). One trial reported lower risk for incident cognitive impairment with minimal versus conventional extracorporeal CABG (risk ratio, 0.34 [95% CI, 0.16 to 0.73]; low SOE). Two trials found no difference between surgical carotid revascularization and carotid stenting or angioplasty (low and insufficient SOE, respectively). One cohort study reported increased cognitive decline after transcatheter versus surgical aortic valve replacement but had large selection and outcome measurement biases (insufficient SOE).

LIMITATIONS

Mostly low to insufficient SOE; no pertinent data for ablation; limited generalizability to the most elderly patients, women, and persons with substantial baseline cognitive impairment; and possible selective reporting and publication bias.

CONCLUSION

Intermediate- and long-term cognitive impairment in older adults attributable to the studied cardiovascular procedures may be uncommon. Nevertheless, clinicians counseling patients before these procedures should discuss the uncertainty in their risk for adverse cognitive outcomes.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality.

Preexisting cognitive status is associated with reduced behavioral functional capacity in patients 3 months after cardiac surgery: an extension study

OBJECTIVE

To examine whether preexisting cognitive status rather than short- and middle-term postoperative cognitive decline (POCD) may differentially account for behavioral functional capacity 3 months after cardiac surgery.

METHOD

Seventy-nine patients completed a psychological evaluation, including the Trail Making Test Part B, the memory with 10-s interference, the phonemic fluency and the Instrumental Activities of Daily Living (IADLs) questionnaire for cognitive functions and behavioral functional capacity, respectively, before surgery, at discharge and at 3-month follow-up.

RESULTS

Thirty-one (39%) and 22 (28%) patients showed POCD at discharge and at 3-month follow-up, respectively. Preoperative cognitive status was significantly associated with change in behavioral functional capacity 3 months after surgery (Ps<.003), whereas short- and middle-term POCD and intraoperative risk factors were unrelated to residualized change in IADLs scores (all Ps>.095).

CONCLUSIONS

Preexisting cognitive deficit, especially working memory deficit, rather than short- and middle-term POCD related to intraoperative risk factors is associated with poor behavioral functional capacity 3 months after cardiac surgery. The present study therefore suggests that a preoperative cognitive evaluation is essential to anticipate which patients are likely to show a decline in behavioral functional capacity after cardiac surgery.

Inflammatory Response in Patients under Coronary Artery Bypass Grafting Surgery and Clinical Implications: A Review of the Relevance of Dexmedetomidine Use

Despite the fact that coronary artery bypass grafting surgery (CABG) with cardiopulmonary bypass (CPB) prolongs life and reduces symptoms in patients with severe coronary artery diseases, these benefits are accompanied by increased risks. Morbidity associated with cardiopulmonary bypass can be attributed to the generalized inflammatory response induced by blood-xenosurfaces interactions during extracorporeal circulation and the ischemia/reperfusion implications, including exacerbated inflammatory response resembling the systemic inflammatory response syndrome (SIRS). The use of specific anesthetic agents with anti-inflammatory activity can modulate the deleterious inflammatory response. Consequently, anti-inflammatory anesthetics may accelerate postoperative recovery and better outcomes than classical anesthetics. It is known that the stress response to surgery can be attenuated by sympatholytic effects caused by activation of central (α-)2-adrenergic receptor, leading to reductions in blood pressure and heart rate, and more recently, that they can have anti-inflammatory properties. This paper discusses the clinical significance of the dexmedetomidine use, a selective (α-)2-adrenergic agonist, as a coadjuvant in general anesthesia. Actually, dexmedetomidine use is not in anesthetic routine, but this drug can be considered a particularly promising agent in perioperative multiple organ protection.

The evolution of cardiovascular surgery in elderly patient: a review of current options and outcomes

Due to the increase in average life expectancy and the higher incidence of cardiovascular disease with advancing age, more elderly patients present for cardiac surgery nowadays. Advances in pre- and postoperative care have led to the possibility that an increasing number of elderly patients can be operated on safely and with a satisfactory outcome. Currently, coronary artery bypass surgery, aortic and mitral valve surgery, and major surgery of the aorta are performed in elderly patients. The data available show that most cardiac surgical procedures can be performed in elderly patients with a satisfactory outcome. Nevertheless, the risk for these patients is only acceptable in the absence of comorbidities. In particular, renal dysfunction, cerebrovascular disease, and poor clinical state are associated with a worse outcome in elderly patients. Careful patient selection, flawless surgery, meticulous hemostasis, perfect anesthesia, and adequate myocardial protection are basic requirements for the success of cardiac surgery in elderly patients. The care of elderly cardiac surgical patients can be improved only through the strict collaboration of geriatricians, anesthesiologists, cardiologists, and cardiac surgeons, in order to obtain a tailored treatment for each individual patient.

Coronary artery bypass graft surgery: the past, present, and future of myocardial revascularisation

The development of the heart-lung machine ushered in the era of modern cardiac surgery. Coronary artery bypass graft surgery (CABG) remains the most common operation performed by cardiac surgeons today. From its infancy in the 1950s till today, CABG has undergone many developments both technically and clinically. Improvements in intraoperative technique and perioperative care have led to CABG being offered to a more broad patient profile with less complications and adverse events. Our review outlines the rich history and promising future of myocardial revascularization.

Effects of a screening and treatment protocol with haloperidol on post-cardiotomy delirium: a prospective cohort study

OBJECTIVES

Post-cardiotomy delirium is common and associated with increased morbidity and mortality. No gold standard exists for detecting delirium, and evidence to support the choice of treatment is needed. Haloperidol is widely used for treating delirium, but indication, doses and therapeutic targets vary. Moreover, doubt has been raised regarding overall efficacy. The purpose of this study was to assess the effect of a combination of early detection and standardized treatment with haloperidol on post-cardiotomy delirium, with the hypothesis that the proportion of delirium- and coma-free days could be increased. Length of stay (LOS), complications and 180-day mortality are reported.

METHODS

Prospective interventional cohort study. One hundred and seventeen adult patients undergoing cardiac surgery were included before introduction of a screening and treatment protocol with haloperidol for delirium, and 123 patients were included after. Nurses screened patients using validated tools (the Delirium Observation Screening (DOS) scale and confusion assessment method for the intensive care unit (CAM-ICU)). In case of delirium, a checklist to eliminate precipitating/ inducing factors and a protocol for standardized dosing with haloperidol was applied. Group comparison was done using non-parametric tests and analysis of fractions, and associations between delirium and predefined covariates were analysed with logistic regression.

RESULTS

Incidence of delirium after cardiac surgery was 21 (14-29) and 22 (15-30) %, onset was on postoperative day 1 (1-4) and 1 (1-3), duration was 1 (1-4) day and 3 (1-5) days, respectively, with no significant difference (Period 1 vs 2, all values are given as the median and 95% confidence interval). The proportion of delirium- and coma-free days was 67 (61-73) and 65 (60-70) %, respectively (ns). There was no difference in LOS or complication rate. Delirium was associated to increasing age, increased length of stay and complications.

CONCLUSIONS

We observed no increase in the proportion of delirium- and coma-free days after introduction of a combination of early detection and standardized treatment with haloperidol on post-cardiotomy delirium. Most patients were not severely affected, and the few who were, proved difficult to treat, indicating that a simple treatment protocol with haloperidol was ineffective.

Sevoflurane preconditioning attenuates the fall in adenosine triphosphate levels, but does not alter the changes in sodium and potassium levels during hypoxia in rat hippocampal slices

BACKGROUND

Sevoflurane preconditioning improves recovery after hypoxia. Sevoflurane administered before and during hypoxia improved recovery and attenuated the changes in intracellular sodium, potassium, and adenosine triphosphate (ATP) levels during hypoxia. In this study, the authors examine the effects of sevoflurane applied only before hypoxia on sodium, potassium, and ATP.

METHODS

Hippocampal slices from adult male Sprague-Dawley rats were pretreated with 4% sevoflurane, washed, and then subjected to hypoxia (n≥8 animals/group). The cornus ammonis 1 regions of the hippocampal slices were micro-dissected and sodium, potassium, and ATP concentrations measured.

RESULTS

Pretreatment with sevoflurane for 15 or 60 min did not attenuate the increase in intracellular sodium or the decrease in intracellular potassium during hypoxia. After 60 min of preconditioning and 5 min of hypoxia, sodium increased 57% (vs. nonpreconditioned hypoxia 54% increase) and potassium decreased 31% (vs. 26%). These changes were not statistically significant versus untreated hypoxia. The 60-min sevoflurane preconditioning group had statistically significant higher ATP levels at 5 min of hypoxia (3.8 nmol/mg dry wt.) when compared to untreated hypoxic tissue (2.1 nmol/mg). There was no significant difference in ATP levels between the sevoflurane preconditioned and the untreated tissue before hypoxia (8.9 vs. 8.5 nmoles/mg, respectively).

CONCLUSION

Preconditioning with sevoflurane for 60 min before hypoxia does not alter changes in intracellular sodium and potassium during hypoxia but does attenuate the fall in intracellular ATP levels during hypoxia. Thus, there are differences between anesthetic preconditioning and when anesthetics are present before and during hypoxia.

Myocardial revascularization for the elderly: current options, role of off-pump coronary artery bypass grafting and outcomes

The increase in life expectancy has confronted cardiac surgery with a rapidly growing population of elderly patients requiring surgical myocardial revascularization. Recent advances in surgical and anesthetic techniques and improvements in postoperative care have made coronary artery bypass grafting an established therapeutic option for the treatment of coronary artery disease in this group of patients. However, conventional coronary artery bypass grafting on cardiopulmonary bypass is associated with significant risk and related morbidity and mortality in the elderly. In recent years off-pump coronary artery bypass grafting has emerged as a safe and less invasive strategy for surgical myocardial revascularization. Off-pump coronary artery bypass grafting by avoiding the deleterious effects of cardiopulmonary bypass can offer potential benefits to elderly patients requiring surgical myocardial revascularization. This review article provides an overview of the age-related cardiovascular changes, epidemiology of coronary artery disease in the elderly and focuses on outcomes of surgical myocardial revascularization with special emphasis on the impact of off-pump coro-nary artery bypass surgery in the elderly.

Are surgical trials with negative results being interpreted correctly?

BACKGROUND

Many published accounts of clinical trials report no differences between the treatment arms, while being underpowered to find differences. This study determined how the authors of these reports interpreted their findings.

STUDY DESIGN

We examined 54 reports of surgical trials chosen randomly from a database of 110 influential trials conducted in 2008. Seven that reported having adequate statistical power (β ≥ 0.9) were excluded from further analysis, as were the 32 that reported significant differences between the treatment arms. We examined the remaining 15 to see whether the authors interpreted their negative findings appropriately. Appropriate interpretations discussed the lack of power and/or called for larger studies.

RESULTS

Three of the 7 trials that did not report an a priori power calculation offered inappropriate interpretations, as did 3 of the 8 trials that reported an a priori power < 0.90. However, we examined only a modest number of trial reports from 1 year.

CONCLUSIONS

Negative findings in underpowered trials were often interpreted as showing the equivalence of the treatment arms with no discussion of the issue of being underpowered. This may lead clinicians to accept new treatments that have not been validated.

Postoperative cognitive dysfunction is correlated with urine formaldehyde in elderly noncardiac surgical patients

Post-operative cognitive dysfunction (POCD), especially in elderly patients, has been reported in many studies. Although increasing age, duration of anesthesia, postoperative infections, and respiratory complications were regarded as the risk factors for POCD, no extracerebral diagnostic biomarkers have been identified as indicators of POCD. Ninety-five patients, ages 65-80 years, scheduled for major orthopedic or abdominal surgery were enrolled. Twenty-two patients aged between 20 and 40 years undergoing the same procedures served as controls. Subjects received neuropsychological tests one-day prior and one week post procedure. To determine the presence of POCD, the criteria were used as described in most previous studies. Morning urine samples were obtained one day before surgery and on day 1, day 2 and day 7 post operatively. Urine formaldehyde was determined with high-performance liquid chromatography. The urine formaldehyde level of all patients with and without POCD increased on the first 2 days after surgery. But the formaldehyde concentration (on day 7) in patients with POCD was significantly higher than that in patients without POCD (p < 0.01). In the young control group, no patient was diagnosed with POCD. Although the changes in urine formaldehyde of young patients during perioperative period were similar to those in elderly patients without POCD, the formaldehyde concentrations measured at four time points were all significantly lower than those in elderly patients (p < 0.05). Levels of urine formaldehyde were elevated in the perioperative period, with the highest levels at day 7 in patients with POCD. This suggests that the increase on day 7 may provide a new physiologic marker along with neuropsychological assessments to assist in the diagnosis of POCD.

Off-pump versus on-pump coronary artery bypass grafting for ischaemic heart disease

BACKGROUND

Coronary artery bypass grafting (CABG) is performed both without and with cardiopulmonary bypass, referred to as off-pump and on-pump CABG respectively. However, the preferable technique is unclear.

OBJECTIVES

To assess the benefits and harms of off-pump versus on-pump CABG in patients with ischaemic heart disease.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (Issue 1, 2011), MEDLINE (OVID, 1950 to February 2011), EMBASE (OVID, 1980 to February 2011), Science Citation Index Expanded on ISI Web of Science (1970 to February 2011) and CINAHL (EBSCOhost, 1981 to February 2011) on 2 February 2011. No language restrictions were applied.

SELECTION CRITERIA

Randomised clinical trials of off-pump versus on-pump CABG irrespective of language, publication status and blinding were selected for inclusion.

DATA COLLECTION AND ANALYSIS

For statistical analysis of dichotomous data risk ratio (RR) and for continuous data mean difference (MD) with 95% confidence intervals (CI) were used. Trial sequential analysis (TSA) was used for analysis to assess the risk of random error due to sparse data and to multiple updating of accumulating data.

MAIN RESULTS

Eighty-six trials (10,716 participants) were included. Ten trials (4,950 participants) were considered to be low risk of bias. Pooled analysis of all trials showed that off-pump CABG increased all-cause mortality compared with on-pump CABG (189/5,180 (3.7%) versus 160/5144 (3.1%); RR 1.24, 95% CI 1.01 to 1.53; P =.04). In the trials at low risk of bias the effect was more pronounced (154/2,485 (6.2%) versus 113/2,465 (4.6%), RR 1.35,95% CI 1.07 to 1.70; P =.01). TSA showed that the risk of random error on the result was unlikely. Off-pump CABG resulted in fewer distal anastomoses (MD -0.28; 95% CI -0.40 to -0.16, P <.00001). No significant differences in myocardial infarction, stroke, renal insufficiency, or coronary re-intervention were observed. Off-pump CABG reduced post-operative atrial fibrillation compared with on-pump CABG, however, in trials at low risk of bias, the estimated effect was not significantly different.

AUTHORS' CONCLUSIONS

Our systematic review did not demonstrate any significant benefit of off-pump compared with on-pump CABG regarding mortality, stroke, or myocardial infarction. In contrast, we observed better long-term survival in the group of patients undergoing on-pump CABG with the use of cardiopulmonary bypass and cardioplegic arrest. Based on the current evidence, on-pump CABG should continue to be the standard surgical treatment. However, off-pump CABG may be acceptable when there are contraindications for cannulation of the aorta and cardiopulmonary bypass. Further randomised clinical trials should address the optimal treatment in such patients.

The role of asymmetry and the nature of microembolization in cognitive decline after heart valve surgery: a pilot study

Our objective was to determine the role of asymmetry and the nature of microembolization on postoperative cognitive decline in patients who had undergone heart valve surgery. Continuous transcranial Doppler ultrasound was intraoperatively used for both middle cerebral arteries in 13 right-handed heart valve surgery patients to detect microembolization. The Trail Making Test A and B, Memory with 10/30 s interference, the Digit Span Test and Phonemic Fluency were performed preoperatively, at discharge and three months after surgery. Our data suggest that early and late postoperative psychomotor and executive functions may be sensitive to microemboli in the left, but not in the right middle cerebral artery. Moreover, solid and gaseous microemboli are both similarly associated with early postoperative cognitive decline while, surprisingly, late postoperative cognitive decline is more likely to be associated with gaseous than solid microemboli.

A comparison of long-term mortality for off-pump and on-pump coronary artery bypass graft surgery

BACKGROUND

The survival difference between off-pump and on-pump coronary artery bypass graft surgery for follow-up longer than 5 years is not well-understood. The objective of this study is to examine the difference in 7-year mortality after these 2 procedures.

METHODS AND RESULTS

The state of New York's Cardiac Surgery Reporting System was used to identify the 2640 off-pump and 5940 on-pump patients discharged from July through December 2000. The National Death Index was used to ascertain patients' vital statuses through 2007. A logistic regression model was fit to predict the probability of receiving an off-pump procedure using baseline patient characteristics. Off-pump and on-pump patients were matched with a 1:1 ratio based on the probability of receiving an off-pump procedure. Kaplan-Meier survival curves for the 2 procedures were compared using the propensity-matched data, and the hazard ratio for death for off-pump in comparison with on-pump procedures was obtained. In subgroup analyses, the significance of interactions between type of surgery and baseline risk factors was tested. In this study, 2631 pairs of off-pump and on-pump patients were propensity matched. The 7-year Kaplan-Meier survival rates were 71.2% and 73.4% (P=0.07) for off-pump and on-pump surgery, respectively. The hazard ratio for death (off-pump versus on-pump) was 1.10 (95% confidence interval: 0.99 to 1.21, P=0.07). No statistical significance was detected for the interaction terms between the type of surgery and a number of different baseline risk factors.

CONCLUSIONS

The difference in long-term mortality between on-pump and off-pump coronary artery bypass graft surgery is not statistically significant.

Brain damage and cardiopulmonary bypass: is there really any association?

Brain damage, in the form of stroke and cognitive deficit associated with heart surgery, has long been attributed unquestioningly to cardiopulmonary bypass (CPB). The aim of this paper is to review the randomised control trials (RCT), systematic reviews and meta-analyses of studies, comparing patients who have undergone on- or off-pump coronary artery bypass grafting (CABG) surgeries that have used stroke or cognition as an outcome to determine whether CPB is associated with brain damage. Although not definitive, the evidence base to date strongly suggests that the incidence of stroke and the effect on cognition, if any, are no different whether CABG surgery is undertaken on- or off-pump. In addition and contrary to long-held beliefs, this review leads to the conclusion that CPB may well not be the cause of the brain damage associated with heart surgery.

Postoperative cognitive deficit after cardiopulmonary bypass with preserved cerebral oxygenation: a prospective observational pilot study

Background

Neurologic deficits after cardiac surgery are common complications. Aim of this prospective observational pilot study was to investigate the incidence of postoperative cognitive deficit (POCD) after cardiac surgery, provided that relevant decrease of cerebral oxygen saturation (cSO2) is avoided during cardiopulmonary bypass.

Methods

cSO2 was measured by near infrared spectroscopy in 35 patients during cardiopulmonary bypass. cSO2 was kept above 80% of baseline and above 55% during anesthesia including cardiopulmonary bypass. POCD was tested by trail making test, digit symbol substitution test, Ray's auditorial verbal learning test, digit span test and verbal fluency test the day before and 5 days after surgery. POCD was defined as a decline in test performance that exceeded - 20% from baseline in two tests or more. Correlation of POCD with lowest cSO2 and cSO2 - threshold were determined explorative.

Results

POCD was observed in 43% of patients. Lowest cSO2 during cardiopulmonary bypass was significantly correlated with POCD (p = 0.015, r2 = 0.44, without Bonferroni correction). A threshold of 65% for cSO2 was able to predict POCD with a sensitivity of 86.7% and a specificity of 65.0% (p = 0.03, without Bonferroni correction).

Conclusions

Despite a relevant decrease of cerebral oxygen saturation was avoided in our pilot study during cardiopulmonary bypass, incidence of POCD was comparable to that reported in patients without monitoring. A higher threshold for cSO2 may be needed to reduce the incidence of POCD.

Measurement of post-operative cognitive dysfunction after cardiac surgery: a systematic review

Post-operative cognitive dysfunction (POCD) is a decline in cognitive function from pre-operative levels, which has been frequently described after cardiac surgery. The purpose of this study was to examine the variability in the measurement and definitions for POCD using the framework of a 1995 Consensus Statement on measurement of POCD. Electronic medical literature databases were searched for the intersection of the search terms 'thoracic surgery' and 'cognition, dementia, and neuropsychological test.' Abstracts were reviewed independently by two reviewers. English articles with >50 participants published since 1995 that performed pre-operative and post-operative psychometric testing in patients undergoing cardiac surgery were reviewed. Data relevant to the measurement and definition of POCD were abstracted and compared with the recommendations of the Consensus Statement. Sixty-two studies of POCD in patients undergoing cardiac surgery were identified. Of these studies, the recommended neuropsychological tests were carried out in less than half of the studies. The cognitive domains measured most frequently were attention (n=56; 93%) and memory (n=57; 95%); motor skills were measured less frequently (n=36; 60%). Additionally, less than half of the studies examined anxiety and depression, performed neurological exam, or accounted for learning. Four definitions of POCD emerged: per cent decline (n=15), standard deviation decline (n=14), factor analysis (n=13), and analysis of performance on individual tests (n=12). There is marked variability in the measurement and definition of POCD. This heterogeneity may impede progress by reducing the ability to compare studies on the causes and treatment of POCD.

Off-pump coronary artery bypass may increase late mortality: a meta-analysis of randomized trials

BACKGROUND

Although a lot of randomized trials of off-pump coronary artery bypass grafting (CABG) versus on-pump CABG were conducted, the majority of them reported only early outcomes. Previous meta-analyses of a few randomized trials found no differences for 1-year to 2-year mortality.

METHODS

We focused late (> or = 1 year) all-cause mortality and performed a meta-analysis of randomized controlled trials of off-pump versus on-pump CABG. The MEDLINE, the EMBASE, and the Cochrane Central Register of Controlled Trials were searched using PubMed and OVID. For each study, data regarding all-cause mortality in both the off-pump and on-pump groups were used to generate risk ratios (RRs) and 95% confidence intervals. Study-specific estimates were combined using inverse variance-weighted averages of logarithmic RRs in both fixed-effects and random-effects models.

RESULTS

Our search identified 11 results of 12 randomized trials (4,326 patients) of off-pump versus on-pump CABG. Pooled analysis demonstrated a statistically significant increase in midterm all-cause mortality by a factor of 1.37 with off-pump relative to on-pump CABG (RR, 1.373; 95% confidence interval, 1.043 to 1.808). Exclusion of any single result, except for the largest (>2,000 patients) trial, from the analysis did not substantively alter the overall result of our analysis. Eliminating the largest trial demonstrated a statistically nonsignificant benefit of on-pump over off-pump CABG for midterm all-cause mortality (RR, 1.344; 95% confidence interval, 0.952 to 1.896).

CONCLUSIONS

The results of our analysis suggest that off-pump CABG may increase late all-cause mortality by a factor of 1.37 over on-pump CABG. Longer term mortality from randomized trials of off-pump versus on-pump CABG is needed.

Baseline cerebral oximetry values in cardiac and vascular surgery patients: a prospective observational study

AIM

This study was conducted to evaluate baseline INVOS values and identify factors influencing preoperative baseline INVOS values in carotid endarterectomy and cardiac surgery patients.

METHODS

This is a prospective observational study on 157 patients (100 cardiac surgery patients, 57 carotid endarterectomy patients). Data were collected on factors potentially related to baseline INVOS values. Data were analyzed with student's t-test, Chi-square, Pearson's correlation or Linear Regression as appropriate.

RESULTS

100 cardiac surgery patients and 57 carotid surgery patients enrolled. Compared to cardiac surgery, carotid endarterectomy patients were older (71.05 +/- 8.69 vs. 65.72 +/- 11.04, P < 0.001), with higher baseline INVOS (P < 0.007) and greater stroke frequency (P < 0.002). Diabetes and high cholesterol were more common in cardiac surgery patients. Right side INVOS values were strongly correlated with left-side values in carotid (r = 0.772, P < 0.0001) and cardiac surgery patients (r = 0.697, P < 0.0001). Diabetes and high cholesterol were associated with significantly (P < 0.001) lower INVOS and smoking was associated with higher INVOS values in carotid, but not in cardiac surgery patients. Age, sex, CVA history, Hypertension, CAD, Asthma, carotid stenosis side and surgery side were not related to INVOS. Multivariate analysis showed that diabetes is strongly associated with lower baseline INVOS values bilaterally (P < 0.001) and explained 36.4% of observed baseline INVOS variability in carotid (but not cardiac) surgery.

CONCLUSION

Compared to cardiac surgery, carotid endarterectomy patients are older, with higher baseline INVOS values and greater stroke frequency. Diabetes and high cholesterol are associated with lower baseline INVOS values in carotid surgery. Right and left side INVOS values are strongly correlated in both patient groups.

Neuropsychological outcomes after coronary artery bypass grafting

Short- and long-term cognitive declines after cardiac surgery with cardiopulmonary bypass have been reported, but the frequency, severity, nature, and etiology of postoperative cognitive changes have been difficult to quantify. Current studies have corrected the principal methodological shortcoming of earlier studies by including control groups, and have shown that while early postoperative cognitive decline does occur in some patients, it is generally mild and reversible by 3 months after surgery. Late cognitive changes do occur, but comparison with patients undergoing off-pump surgery or those being treated medically suggests that these changes are not specific to CABG or more specifically to the use of cardiopulmonary bypass.

Postoperative cognitive dysfunction in the elderly

Despite improvement in surgical techniques, anesthetic management, and intensive care, a significant number of elderly patients develop postoperative cognitive decline. Postoperative cognitive dysfunction (POCD) is a postoperative memory or thinking impairment that has been corroborated by neuropsychological testing, for which increasing age is the leading risk factor. POCD is multifactorial in origin, but it remains unclear whether its occurrence is a result of surgery or general anesthesia. This article discusses the incidence, assessment, consequences, and prevention of POCD, as well as anesthetic strategies to improve cognitive outcome in elderly patients.