Preoperative Statin Therapy Does Not Reduce Cognitive Dysfunction After Cardiopulmonary Bypass

Effects of inflammation and oxidative stress on postoperative delirium in cardiac surgery

The past decade has witnessed unprecedented medical progress, which has translated into cardiac surgery being increasingly common and safe. However, complications such as postoperative delirium remain a major concern. Although the pathophysiological changes of delirium after cardiac surgery remain poorly understood, it is widely thought that inflammation and oxidative stress may be potential triggers of delirium. The development of delirium following cardiac surgery is associated with perioperative risk factors. Multiple interventions are being explored to prevent and treat delirium. Therefore, research on the potential role of biomarkers in delirium as well as identification of perioperative risk factors and pharmacological interventions are necessary to mitigate the development of delirium.

Targeted temperature management in cardiac surgery: a systematic review and meta-analysis on postoperative cognitive outcomes

BACKGROUND

Postoperative cognitive decline occurs commonly after cardiac surgery. The available literature is inconclusive on the role of intraoperative causal or protective factors.

METHODS

We systematically reviewed studies evaluating delayed neurocognitive recovery (DNR), postoperative neurocognitive disorder (NCD), stroke, and the mortality rates among patients undergoing hypothermic or normothermic cardiopulmonary bypass (CPB). We further performed a subgroup analysis for age, surgery type (coronary artery bypass grafting [CABG], valve surgery, or combined), and the mean arterial blood pressure (MAP) during CPB, and conducted a proportion meta-analysis after calculation of single proportions and confidence intervals (CIs).

RESULTS

We included a total of 58 studies with 9609 patients in our analysis. Among these, 1906 of 4010 patients (47.5%) had DNR, and 2071 of 7160 (28.9%) had postoperative NCD. Ninety of 4625 patients (2.0%) had a stroke, and 174 of 7589 (2.3%) died. There was no statistically significant relationship between the considered variables and DNR, NCD, stroke, and mortality. In the subgroup analysis comparing hypothermic with normothermic CPB, we found higher NCD rates after combined surgery; for normothermic CPB cases only, the rates of DNR and NCD were lower after combined surgery compared with CABG surgery. A MAP >70 mm Hg compared with MAP=50-70 mm Hg during CPB was associated with a lower rate of DNR.

CONCLUSIONS

Temperature, MAP during cardiopulmonary bypass age, and surgery type were not associated with neurocognitive disorders, stroke, and mortality in cardiac surgery. Normothermic cardiopulmonary bypass, particularly when performed with MAP >70 mm Hg, may reduce the risk of postoperative neurocognitive decline after cardiac surgery.

PROSPERO REGISTRATION NUMBER

CRD42019140844.

Effects of propofol and surgery on neuropathology and cognition in the 3xTgAD Alzheimer transgenic mouse model

Background

Previous work suggests that anaesthesia and surgery amplify the pathology and cognitive impairment of animals made vulnerable via age or specific transgenes. We hypothesized that surgery under propofol anaesthesia, a widely used i.v. general anaesthetic, has minimal delayed cognitive and neuroinflammatory sequelae in a vulnerable mouse transgenic model.

Methods

We conducted caecal ligation and excision surgery in cognitively presymptomatic (11-month-old) 3xTgAD mice under i.p. propofol anaesthesia. Age-matched 3xTgAD control mice received vehicle or propofol without surgery. Morris water maze testing was conducted 3 and 15 weeks later. Brains were examined with quantitative immunohistochemistry for amyloid β plaques, tau pathology, and microglial activation. Acute changes in neuroinflammatory cytokines were assessed in separate cohorts at 6 h.

Results

We detected no significant differences between groups in escape latencies at either 3 or 15 weeks, but detected a significant effect of surgery in the probe test at both 3 and 15 weeks. Spatial working memory was unaffected at 16 weeks in any group. No effects of either propofol alone or propofol with surgery were detected on plaque formation, tau aggregates, or neuroinflammation. Acute biochemical assays detected no effects in brain interleukin-10 or interleukin-6 concentrations.

Conclusions

Surgery in a vulnerable transgenic mouse under propofol anaesthesia was associated with minimal to no changes in short- and long-term behaviour and no changes in neuropathology. This suggests that propofol anaesthesia is associated with better cognitive outcomes in the aged, vulnerable brain compared with inhalation anaesthesia.

Associations of dyslipidaemia and lipid-lowering treatment with risk of postoperative cognitive dysfunction: a systematic review and meta-analysis

BACKGROUND

Lipid imbalance is linked to age-related cognitive impairment, but its role in postoperative cognitive dysfunction (POCD) is unknown. Here, we present a systematic review and meta-analysis on dyslipidaemia, lipid-lowering treatment and POCD risk.

METHODS

PubMed, Ovid SP and Cochrane databases were searched for longitudinal studies that reported on associations of any measure of dyslipidaemia and/or lipid-lowering treatment with POCD as relative risks (RRs) or ORs. Fixed-effects inverse variance models were used to combine effects.

RESULTS

Of 205 articles identified in the search, 17 studies on 2725 patients (grand mean age 67 years; mean age range 61-71 years) with follow-up periods of 1 day to 4 years (median 7 days; IQR 1-68 days) were included. Studies focused almost exclusively on hypercholesterolaemia as a measure of dyslipidaemia and on statins as lipid-lowering treatment. Across 12 studies on hypercholesterolaemia, we found no association with POCD risk (RR 0.93; 95% CI 0.80 to 1.08; P=0.34). Statin use before surgery was associated with a reduced POCD risk across eight studies (RR 0.81; 95% CI 0.67 to 0.98; P=0.03), but data on treatment duration were lacking.

CONCLUSION

Statin users appear to be at reduced risk of POCD although hypercholesterolaemia per se may not be associated with POCD risk. Trial studies are needed to evaluate the usefulness of statins in POCD prevention.

Post-Operative Cognitive Dysfunction: An exploration of the inflammatory hypothesis and novel therapies

Post-Operative Cognitive Dysfunction (POCD) is a highly prevalent condition with significant clinical, social and financial impacts for patients and their communities. The underlying pathophysiology is becoming increasingly understood, with the role of neuroinflammation and oxidative stress secondary to surgery and anaesthesia strongly implicated. This review aims to describe the putative mechanisms by which surgery-induced inflammation produces cognitive sequelae, with a focus on identifying potential novel therapies based upon their ability to modify these pathways.

Lack of Association between Preoperative Statin Use and Respiratory and Neurologic Complications after Cardiac Surgery

Background

Statins may reduce the risk of pulmonary and neurologic complications after cardiac surgery.

Methods

The authors acquired data for adults who had coronary artery bypass graft, valve surgery, or combined procedures. The authors matched patients who took statins preoperatively to patients who did not. First, the authors assessed the association between preoperative statin use and the primary outcomes of prolonged ventilation (more than 24 h), pneumonia (positive cultures of sputum, transtracheal fluid, bronchial washings, and/or clinical findings consistent with the diagnosis of pneumonia), and in-hospital all-cause mortality, using logistic regressions. Second, the authors analyzed the collapsed composite of neurologic complications using logistic regression. Intensive care unit and hospital length of stay were evaluated with Cox proportional hazard models.

Results

Among 14,129 eligible patients, 6,642 patients were successfully matched. There was no significant association between preoperative statin use and prolonged ventilation (statin: 408/3,321 [12.3%] vs. nonstatin: 389/3,321 [11.7%]), pneumonia (44/3,321 [1.3%] vs. 54/3,321 [1.6%]), and in-hospital mortality (52/3,321 [1.6%] vs. 43/3,321 [1.3%]). The estimated odds ratio was 1.06 (98.3% CI, 0.88 to 1.27) for prolonged ventilation, 0.81 (0.50 to 1.32) for pneumonia, and 1.21 (0.74 to 1.99) for in-hospital mortality. Neurologic outcomes were not associated with preoperative statin use (53/3,321 [1.6%] vs. 56/3,321 [1.7%]), with an odds ratio of 0.95 (0.60 to 1.50). The length of intensive care unit and hospital stay was also not associated with preoperative statin use, with a hazard ratio of 1.04 (0.98 to 1.10) for length of hospital stay and 1.00 (0.94 to 1.06) for length of intensive care unit stay.

Conclusions

Preoperative statin use did not reduce pulmonary or neurologic complications after cardiac surgery.

Effect of preoperative statin therapy on early postoperative memory impairment after off-pump coronary artery bypass surgery

Context:

Frequent incidence of early postoperative memory impairment (POMI) after cardiac surgery remains a concern because of associated morbidity, impaired quality of life, and increased health care cost.

Aim:

To assess the effect of preoperative statin therapy on POMI in patients undergoing off-pump coronary artery bypass (OPCAB) surgery.

Setting and Design:

Prospective observational study in a tertiary level hospital.

Methods:

Sixty patients aged 45–65 years undergoing OPCAB surgery were allocated into two groups of 30 each. Group A patients were receiving statin and Group B patients were not receiving statins. All patients underwent memory function assessment preoperatively after admission to hospital and on the 6^th postoperative day using postgraduate institute memory scale.

Statistical Analysis:

Appropriate tests were applied with SPSS 20 to compare both groups. The value P < 0.05 was considered statistically significant. Multiple regression analysis was performed with confounding factors to determine the effect on memory impairment.

Results:

Patients in Group A showed significant postoperative deterioration in 6 of the 10 functions and in Group B showed deterioration in 9 of 10 functions tested compared to preoperative scores. Intergroup comparison detected less POMI in Group A compared to Group B and was statistically significant in 8 memory functions. Multiple regression analysis detected statin as an independent factor in preventing memory impairment.

Conclusions:

Preoperative statin therapy attenuates the early POMI in patients undergoing OPCAB. Future long-term studies will define the efficacy of statin on POMI.

Efficacy of Different Perioperative Statin Regimens on Protection Against Post-Coronary Artery Bypass Grafting Major Adverse Cardiac and Cerebral Events

OBJECTIVES

Comparing different perioperative statin regimens for the prevention of post-coronary artery bypass grafting adverse events.

DESIGN

A randomized, prospective study.

SETTING

Cardiothoracic surgical units in a government hospital.

PARTICIPANTS

The study comprised 94 patients scheduled for elective, isolated on- or off- pump coronary artery bypass grafting.

INTERVENTIONS

Patients were assigned randomly to 1 of the following 3 treatment groups: group I (80 mg of atorvastatin/day for 2 days preoperatively), group II (40 mg of atorvastatin/day for 5-9 days preoperatively), or group III (80 mg of atorvastatin/day for 5-9 days preoperatively). The same preoperative doses were restarted postoperatively and continued for 1 month.

MEASUREMENTS AND MAIN RESULTS

Cardiac troponin I, creatine kinase, and C-reactive protein (CRP) levels were assayed preoperatively; at 8, 24, and 48 hours postoperatively; and at discharge. CRP levels at 24 hours (p = 0.045) and 48 hours (p = 0.009) were significantly lower in group III compared with the other 2 groups. However, troponin I levels at 8 hours (p = 0.011) and 48 hours (p = 0.025) after surgery were significantly lower in group II compared with group III. The incidence of postoperative major adverse cardiac and cerebrovascular events was assessed, and there was no significant difference among the 3 groups.

CONCLUSION

The 3 regimens did not result in any significant difference in outcomes, but only simple trends. The higher-dose regimen resulted in a significant reduction in the CRP level. Thus, more studies are needed to confirm the benefit of higher-dose statins for the protection from post-coronary artery bypass grafting adverse events.

Does the use of statins improve outcomes in coronary artery bypass graft surgery?

Statins (3-hydroxy-3-methylglutaryl CoA reductase inhibitors) are one of the most frequently prescribed medications throughout the world with beneficial effects that extend beyond their lipid-lowering activity. It has been suggested that statins may offer a simple and cost-effective strategy to reduce some of the complications that occur in association with coronary artery bypass graft (CABG) surgery. Limited existing randomized trial evidence in the setting of cardiac surgery suggests that statins may reduce the incidence of postoperative atrial fibrillation. However, any effect of statins on other outcomes is less clear. The clinical significance of specific statin agent and dose, acute statin withdrawal and the potential benefits associated with statin reloading remain important yet currently unresolved issues. Despite limited high-quality evidence, class I recommendations have been made that all patients undergoing coronary artery bypass graft surgery should receive statin therapy unless contraindicated.

Risk Factors Associated with Cognitive Decline after Cardiac Surgery: A Systematic Review

Modern day cardiac surgery evolved upon the advent of cardiopulmonary bypass machines (CPB) in the 1950s. Following this development, cardiac surgery in recent years has improved significantly. Despite such advances and the introduction of new technologies, neurological sequelae after cardiac surgery still exist. Ischaemic stroke, delirium, and cognitive impairment cause significant morbidity and mortality and unfortunately remain common complications. Postoperative cognitive decline (POCD) is believed to be associated with the presence of new ischaemic lesions originating from emboli entering the cerebral circulation during surgery. Cardiopulmonary bypass was thought to be the reason of POCD, but randomised controlled trials comparing with off-pump surgery show contradictory results. Attention has now turned to the growing evidence that perioperative risk factors, as well as patient-related risk factors, play an important role in early and late POCD. Clearly, identifying the mechanism of POCD is challenging. The purpose of this systematic review is to discuss the literature that has investigated patient and perioperative risk factors to better understand the magnitude of the risk factors associated with POCD after cardiac surgery.

Statin use and risk of delirium in the critically ill

RATIONALE

Delirium is common in intensive care unit (ICU) patients and is a predictor of worse outcomes and neuroinflammation is a possible mechanism. The antiinflammatory actions of statins may reduce delirium.

OBJECTIVES

To determine whether critically ill patients receiving statin therapy had a reduced risk of delirium than those not on statins.

METHODS

A prospective cohort analysis of data from consecutive ICU patients admitted to a UK mixed medical and surgical critical care unit between August 2011 and February 2012; the Confusion Assessment Method for ICU was used to determine the days each patient was assessed as being free of delirium during ICU admission.

MEASUREMENTS AND MAIN RESULTS

Delirium-free days, daily administration of statins, and serum C-reactive protein (CRP) were recorded. Four hundred and seventy consecutive critical care patients were followed, of whom 151 patients received statins. Using random-effects multivariable logistic regression, statin administration the previous evening was associated with the patient being assessed as free of delirium (odds ratio, 2.28; confidence interval, 1.01-5.13; P < 0.05) and with lower CRP (β = -0.52; P < 0.01) the following day. When the association between statin and being assessed as free of delirium was controlled for CRP, the effect size became nonsignificant (odds ratio, 1.56; confidence interval, 0.64-3.79; P = 0.32).

CONCLUSIONS

Ongoing statin therapy is associated with a lower daily risk of delirium in critically ill patients. An ongoing clinical trial, informed by this study, is investigating if statins are a potential therapy for delirium in the critically ill.

Preoperative statin therapy is not associated with a decrease in the incidence of delirium after cardiac operations

BACKGROUND

Delirium after cardiac operations is associated with significant morbidity and death. Statins have been recently suggested to exert protective cerebral effects. This study investigated whether preoperative statins were associated with decreased incidence of postoperative delirium in patients undergoing coronary artery bypass grafting.

METHODS

The study enrolled 4,659 consecutive patients (21% women; age, 67.8±9.2 years) undergoing coronary artery bypass grafting. A propensity score-based optimal-matching algorithm was used to match 1,577 patients receiving preoperative statins with a control group (1:1). Patients were screened for delirium in the intensive care unit according to the Confusion Assessment Method for the intensive care unit.

RESULTS

Delirium affected 89 patients (3%), and preoperative statin administration was not multivariably associated with a decreased incidence of delirium (odds ratio, 1.52; 95% confidence interval, 0.97 to 2.37; p=0.18) and was also unrelated to a delirium decrease in patient subgroups undergoing isolated coronary artery bypass grafting (odds ratio, 1.31; 95% confidence interval, 0.68 to 2.52; p=0.51) or combined valvular procedures (odds ratio, 1.72; 95% confidence interval, 0.96 to 3.07, p=0.08). Similar results were observed for age groups and cardiopulmonary bypass durations. Patients affected by postoperative delirium experienced a longer hospital stay (25th to 75th percentile) of 11 (7 to 18 days) vs 7 days (7 to 8 days, p<0.001) and 12% hospital mortality vs 1% (p<0.001).

CONCLUSIONS

Preoperative statins were not associated with a decreased incidence of delirium in patients undergoing coronary revascularization.

Integrating outcome benefit into anesthetic design: the promise of steroids and statins

Steroids and statins may facilitate the integration of anesthetic design with clinical outcome. Although steroids clearly benefit adult cardiac surgical patents, the evidence is weaker in pediatric cardiac surgery. Current large randomized trials of steroids likely will determine the future role of steroids in adult cardiac surgery. In the intensive care unit, steroid therapy is indicated in septic shock that is refractory to fluid and pressor therapy. Recent data, however, indicate that liberal steroid therapy for sepsis may have adverse outcome consequences. A 2nd concern in the intensive care unit is acute adrenal suppression secondary to bolus etomidate therapy because it may be deleterious in patients with septic shock. Possible clinical solutions include alternative induction agents, concomitant steroid therapy, and recent etomidate derivatives. Statins also reduce mortality and atrial fibrillation after cardiac surgery. Furthermore, they slow the progression of rheumatic valvular stenosis, an important consideration in the developing world. Statins also may reduce delirium, stroke, and acute renal injury after cardiac surgery, but further randomized trials are required before definitive recommendations can be formulated. Statins are essential in vascular surgery because they reduce mortality, myocardial ischemia, and acute renal injury. As a result, they have been recommended highly for outcome enhancement in recent perioperative guidelines. Although they may improve survival in sepsis, further investigation is indicated to define their therapeutic role.

Can postoperative cognitive dysfunction be avoided?

Postoperative cognitive dysfunction (POCD) refers to a postoperative decline in cognitive function compared with preoperative cognitive function. Diagnosis requires pre- and postoperative testing, the latter of which is usually performed both 7 days and 3 months postoperatively. Although several risk factors for POCD have been described, age is the only consistently reported risk factor. Postoperative cognitive dysfunction is often transient. It may last several months, and is associated with leaving the labor market prematurely and increased mortality. As the pathophysiology of POCD is still a matter of debate and is likely to be multifactorial, there are no widely accepted prophylactic and therapeutic interventions. In this article, we discuss POCD's definition, risk factors, long-term significance, and pathophysiology. We also present data on prophylactic interventions that have been investigated in clinical trials.

Progress in perioperative medicine: focus on statins

Beyond cholesterol reduction, statins have multiple beneficial influences on vascular endothelial function, atherosclerotic plaque stability, inflammation, and thrombosis. These favorable pleiotropic effects may be the basis for their perioperative risk reduction in cardiothoracic and vascular procedures. The published evidence suggests that statins offer significant outcome benefits throughout perioperative practice. Because statin therapy significantly reduces the perioperative risk for patients undergoing cardiovascular procedures, they already are recommended in published guidelines. Beyond cardiac risk reduction, statin therapy also may protect the brain and the kidney in the perioperative setting, both in cardiac and vascular surgery. The pleiotropic effects of statins also appear to have therapeutic roles in the progression of valve disease, sepsis, and venous thrombosis. Further trials are required to provide data to drive their safe and comprehensive perioperative application for optimal patient outcome both in the short term and the long term. Because there are multiple randomized trials currently in progress throughout perioperative medicine, it is very likely that the indications for statins will be expanded significantly.

Impact of preoperative statin therapy on adverse postoperative outcomes in patients undergoing cardiac surgery: a meta-analysis of over 30,000 patients

AIMS

To determine the strength of evidence for preoperative statin use for prevention of adverse postoperative outcomes in patients undergoing cardiac surgery.

METHODS AND RESULTS

After literature search in major databases, 19 studies were identified [three RCT (randomized prospective clinical trials), 16 observational] that reported outcomes of 31 725 cardiac surgery patients with (n = 17 201; 54%) or without (n = 14 524; 46%) preoperative statin therapy. Outcomes that were analysed included early all-cause mortality (30-day mortality), myocardial infarction (MI), atrial fibrillation (AF), stroke and renal failure. Odds ratio (OR) with 95% confidence intervals (95%CI) were reported using fixed or random effect models and publication bias was assessed. Preoperative statin therapy resulted in a 1.5% absolute risk reduction (2.2 vs. 3.7%; P < 0.0001) and 43% odds reduction for early all-cause mortality (OR 0.57; 95%CI: 0.49-0.67). A significant reduction (P < 0.01) in statin pretreated patients was also observed for AF (24.9 vs. 29.3%; OR 0.67, 95%CI: 0.51-0.88), stroke (2.1 vs. 2.9%, OR 0.74, 95%CI: 0.60-0.91), but not for MI (OR 1.11; 95%CI: 0.93-1.33) or renal failure (OR 0.78, 95%CI: 0.46-1.31). Funnel plot and Egger's regression analysis (P = 0.60) excluded relevant publication bias.

CONCLUSION

Our meta-analysis provides evidence that preoperative statin therapy exerts substantial clinical benefit on early postoperative adverse outcomes in cardiac surgery patients, but underscores the need for RCT trials.

The role of statins in cancer therapy

Administration of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, to ambulatory patients is associated with a lower incidence of long-term adverse cardiovascular events, including death, myocardial infarction, stroke, atrial fibrillation, and renal dysfunction. However, increasing clinical evidence suggests that statins, independent of their effects on serum cholesterol levels, may also play a potential role in the prevention and treatment of cancer. Specifically, statins have been shown to exert several beneficial antineoplastic properties, including decreased tumor growth, angiogenesis, and metastasis. The feasibility and efficacy of statins for the prevention and treatment of cancer is reviewed.

Relationship between white cell count, neuropsychologic outcome, and microemboli in 161 patients undergoing coronary artery bypass surgery

OBJECTIVE

Neuropsychologic impairment remains a problem after coronary artery bypass grafting. Relatively few studies have examined the potential role of the perioperative inflammatory response. This study aimed to determine whether there was any association between perioperative white cell count, microemboli, and cognitive performance after surgical intervention.

METHODS

White cell count and differential were prospectively measured perioperatively in 161 patients undergoing coronary artery bypass grafting. A neuropsychologic test battery (9 tests) was administered preoperatively and 6 to 8 weeks postoperatively in all 161 patients. Cerebral microemboli during cardiopulmonary bypass were also recorded by means of a transcranial Doppler scan of the right middle cerebral artery.

RESULTS

There was no correlation between microemboli and white cell counts at any time point. There were weak but significant inverse correlations between both preoperative (r = -0.19, P = .02) and postoperative (r = -0.21, P < .01) white cell count and a measure of overall neuropsychologic test performance (total z change score). There was a weak but significant positive correlation between the neutrophil count 10 minutes after bypass and the intraoperative microemboli count (r = 0.23, P = .01).

CONCLUSIONS

The correlation between white cell count and neuropsychologic outcome suggests that an inflammatory response might have a role in determining cognitive outcome after coronary artery surgery with cardiopulmonary bypass. The positive correlation between the microemboli during cardiopulmonary bypass and the neutrophil count 10 minutes after bypass is compatible with microemboli contributing to the inflammatory response. The patients' preoperative inflammatory status might also be predictive of the response to surgical intervention.