Cognitive Function in Candidates for Coronary Artery Bypass Graft Surgery

Long-term cognitive decline and mortality after carotid endarterectomy

OBJECTIVES

To date no studies have evaluated long term cognitive decline after carotid endarterectomy (CEA). We evaluated whether participants who had CEA were at increased risk of cognitive decline over participants who didn't undergo CEA.

PATIENTS AND METHODS

The patients in the study were participants in the Cardiovascular Health Study (CHS), a study of 5201 men and women over the age of 65 who were recruited from four communities (Pittsburgh, Pennsylvania; Sacramento, California; Winston-Salem, North Carolina; Hagerstown, Maryland) in 1988-89. The outcomes measured were 1) Decline in 3MSE and digit symbol substitution test (DSST) scores after CEA compared to before CEA. 2) All-cause mortality in CHS cohort among participants who did and did not have CEA.

RESULTS

CEA patients had significantly greater annual decrease in the DSST scores -2.43 (SD 4.21) compared to those who did not have a CEA -1.1 (SD 2.57) (p < 0.001) but this was not seen in the 3MSE scores. CEA patients had increased the risk of decline in DSST (OR 2.41, 95 % CI 1.49, 3.88) and 3MSE (OR 2.17, 95 % CI 1.35, 3.48) scores after adjusting for age, gender, race and educational status. CEA was associated with all-cause mortality in the long term with a HR of 2.72 (95 % CI 2.22, 3.34) after adjusting for covariates. Participants with lower baseline 3MSE scores HR 1.39 (1.27, 1.51), lower DSST scores <34 HR 1.69(1.54, 1.85) were more likely deceased.

CONCLUSIONS

CEA patients are at increased risk of lower scores on 3MSE and DSST testing in the long term. Mortality in the CHS cohort was higher in participants who underwent CEA. Further, lower 3MSE and DSST scores increased the risk of mortality.

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.

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.

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.

CAMTA1 T polymorphism is associated with neuropsychological test performance in older adults with cardiovascular disease

BACKGROUND

Cardiovascular disease has long been associated with poor neurocognitive outcome, with multiple pathophysiological mechanisms that are linked to cognitive impairment in older adults. Although less frequently examined, insulin dysregulation is known to affect vascular function and the associated brain dysfunction in cardiovascular disease. Accordingly, genetic factors tied to insulin regulation may make certain people with cardiovascular disease more susceptible to cognitive dysfunction. Specifically, the calmodulin-binding transcription activator 1 (CAMTA1) genotype, which has been examined as a risk factor for Type 2 diabetes and has been linked to reduced episodic memory performance in healthy young adults, is a potential candidate gene.

METHODS

Blood samples were obtained from 113 older adults with cardiovascular disease who also underwent neuropsychological testing. Carriers of either one or two copies of the T allele of CAMTA1 were categorized into one group (n = 63), whereas non-carriers were categorized into a second group (n = 50).

RESULTS

Analyses showed that carriers of the T allele performed more poorly on tests of attention, executive function, and psychomotor speed, but not on tests of memory. Carriers of the T allele also performed more poorly on a measure of global cognitive function.

CONCLUSIONS

Results indicate that CAMTA1 genotype is associated with cognitive function in older adults with cardiovascular disease, because carriers of the T allele performed more poorly on tests of attention, executive function, and psychomotor speed. Contrary to expectations, there were no differences in memory performance among carriers and non-carriers of the T allele. Given these mixed findings, further studies are necessary to elucidate the association between CAMTA1 and cognition, particularly gene expression and neuroimaging studies.

Independent association between preoperative cognitive status and discharge location after cardiac surgery

BACKGROUND

Among cardiac surgery patients, those with impaired cognitive status before surgery may have longer postoperative stays than do patients with normal status and may require additional care upon discharge.

OBJECTIVES

To determine if preoperative scores on a screening measure for cognitive status (the Clock-in-the-Box), were associated with postoperative length of stay and discharge to a location other than home in patients who had cardiac surgery.

METHODS

A total of 181 consecutive patients scheduled for cardiac surgery at a single site were administered the Clock-in-the-Box as part of the preoperative evaluation. Scores on the Clock-in-the-Box tool, demographic and operative information, postoperative length of stay, and discharge location were collected retrospectively from medical records.

RESULTS

The mean age of the patients was 68.1 years (SD, 0.7), and 99% were men. Mean postoperative length of stay was 10.5 days (SD, 8.2), and 35 patients (19%) were discharged to a facility. Scores on the Clock-in-the-Box assessment were not associated with postoperative length of stay. Increasing age, living alone before surgery, and duration of cardiopulmonary bypass were associated with discharge to a facility and were used as covariates in adjusted analyses. After adjustment, better preoperative cognitive status reduced the risk of being discharged to a facility (adjusted relative risk, 0.93; 95% confidence interval, 0.89-0.98) after cardiac surgery.

CONCLUSIONS

Cognitive screening before cardiac surgery can identify patients with impaired cognitive status who are less likely than patients with normal cognitive status to return home after cardiac surgery.

Development of a unidimensional composite measure of neuropsychological functioning in older cardiac surgery patients with good measurement precision

The objective of this analysis was to develop a measure of neuropsychological performance for cardiac surgery and to assess its psychometric properties. Older patients (n = 210) underwent a neuropsychological battery using nine assessments. The number of factors was identified with variable reduction methods. Factor analysis methods based on item response theory were used to evaluate the measure. Modified parallel analysis supported a single factor, and the battery formed an internally consistent set (coefficient alpha = .82). The developed measure provided a reliable, continuous measure (reliability > .90) across a broad range of performance (-1.5 SDs to +1.0 SDs) with minimal ceiling and floor effects.

Effects of age and coronary artery disease on cerebrovascular reactivity to carbon dioxide in humans

Alterations in cerebrovascular reactivity to CO2, an index of cerebrovascular function, have been associated with increased risk of stroke. We hypothesised that cerebrovascular reactivity is impaired with increasing age and in patients with symptomatic coronary artery disease (CAD). Cerebrovascular and cardiovascular reactivity to CO2 was assessed at rest and during hypercapnia (5% CO2) and hypocapnia (hyperventilation) in subjects with symptomatic CAD (n=13) and age-matched old (n=9) and young (n=20) controls without CAD. Independent of CAD, reductions in middle cerebral artery blood velocity (transcranial Doppler) and cerebral oxygenation (near-infrared spectroscopy) were correlated with increasing age (r = -0.68, r = -0.51, respectively, P < 0.01). In CAD patients, at rest and during hypercapnia, cerebral oxygenation was lower (P < 0.05 vs. young). Although middle cerebral artery blood velocity reactivity was unaltered in the hypercapnic range, middle cerebral artery blood velocity reactivity to hypocapnia was elevated in the CAD and age-matched controls (P < 0.01 vs. young), and was associated with age (r = 0.62, P < 0.01). Transient drops in arterial PCO2 occur in a range of physiological and pathophysiological situations, therefore, the elevated middle cerebral artery blood velocity reactivity to hypocapnia combined with reductions in middle cerebral artery blood velocity may be important mechanisms underlying neurological risk with aging. In CAD patients, additional reductions in cerebral oxygenation may place them at additional risk of cerebral ischaemia.

Neurocognitive dysfunction following cardiac surgery

Postoperative neurocognitive decline (POCD) is the most frequently reported form of brain injury in the cardiac surgery setting. Even though most patients recover over a period of several months, recovery is variable and often transient, and early decline may be a marker of neurocognitive dysfunction after several years. Recent studies, however, suggest that late neurocognitive decline after coronary artery bypass graft surgery may not be specific to the use of cardiopulmonary bypass. Large prospective, longitudinal trials with appropriate controls remain necessary to identify how patient characteristics, disease progression, and surgical and anesthetic technique contribute to aging-related neurocognitive decline. This article reviews the current literature on the etiology of POCD following cardiac surgery, discusses strategies to reduce patient risk, and provides some insight into some controversies that merit continued investigation.

Cognitive function in patients undergoing coronary angiography

OBJECTIVE

To measure cognition in patients before and after coronary angiography.

DESIGN

Prospective observational cohort study.

SETTING

University teaching hospital.

PATIENTS

56 patients presenting for elective coronary angiography.

MAIN OUTCOME MEASURES

Computerised cognitive test battery administered before coronary angiography, before discharge from hospital and 7 days after discharge. A matched healthy control group was used as a comparator.

RESULTS

When analysed by group, coronary angiography patients performed worse than matched controls at each time point. When the cognitive change was examined for each individual, of the 48 patients tested at discharge, 19 (39.6%) were classified as having a new cognitive dysfunction, and of 49 patients tested at day 7, six (12.2%) were classified as having a new cognitive dysfunction.

CONCLUSIONS

The results confirm that cognitive function is decreased in patients who have cardiovascular disease. Furthermore, coronary angiography may exacerbate this impaired cognition in some patients.

Do management strategies for coronary artery disease influence 6-year cognitive outcomes?

BACKGROUND

Previous uncontrolled studies have suggested that there is late cognitive decline after coronary artery bypass grafting that may be attributable to use of the cardiopulmonary bypass pump.

METHODS

In this prospective, nonrandomized, longitudinal study, we compared cognitive outcomes after on-pump coronary artery bypass surgery (n = 152) with off-pump bypass surgery patients (n = 75); nonsurgical cardiac comparison subjects (n = 99); and 69 heart-healthy comparison (HHC) subjects. The primary outcome measure was change from baseline to 72 months in the following cognitive domains: verbal memory, visual memory, visuoconstruction, language, motor speed, psychomotor speed, attention, executive function, and a composite global score.

RESULTS

There were no consistent differences in 72-month cognitive outcomes among the three groups with coronary artery disease (CAD). The CAD groups had lower baseline performance, and a greater degree of decline compared with HHC. The degree of change was small, with none of the groups having more than 0.5 SD decline. None of the groups was substantially worse at 72 months compared with baseline.

CONCLUSIONS

Compared with subjects with no vascular disease risk factors, the CAD patients had lower baseline cognitive performance and greater degrees of decline over 72 months, suggesting that in these patients, vascular disease may have an impact on cognitive performance. We found no significant differences in the long-term cognitive outcomes among patients with various CAD therapies, indicating that management strategy for CAD is not an important determinant of long-term cognitive outcomes.

Clinical outcomes in randomized trials of off- vs. on-pump coronary artery bypass surgery: systematic review with meta-analyses and trial sequential analyses

AIMS

To assess the clinical outcomes of off- vs. on-pump coronary artery bypass surgery in randomized trials.

METHODS AND RESULTS

We searched electronic databases and bibliographies until June 2007. Trials were assessed for risk of bias. Outcome measures were all-cause mortality, myocardial infarction, stroke, atrial fibrillation, and renewed coronary revascularization at maximum follow-up. We applied trial sequential analysis to estimate the strength of evidence. We found 66 randomized trials. There was no statistically significant differences regarding mortality [relative risk (RR) 0.98; 95% confidence interval (CI) 0.66-1.44], myocardial infarction (RR 0.95; 95% CI 0.65-1.37), or renewed coronary revascularization (RR 1.34; 95% CI 0.83-2.18). We found a significant reduced risk of atrial fibrillation (RR 0.69; 95% CI 0.57-0.83) and stroke (RR 0.53; 95% CI 0.31-0.91) in off-pump patients. However, when continuity correction for zero-event trials was included, the reduction in stroke became insignificant (RR 0.62; 95% CI 0.32-1.19). Trial sequential analysis demonstrated overwhelming evidence supporting that off-pump bypass surgery reduces atrial fibrillation.

CONCLUSION

Off-pump surgery reduces the risks of postoperative atrial fibrillation compared with on-pump surgery. For death, myocardial infarction, stroke, and renewed coronary revascularization, the evidence is still weak and more low-bias risk trials are needed.

Predictors of cognitive function in candidates for coronary artery bypass graft surgery

Candidates for coronary artery bypass graft surgery have been found to exhibit reduced cognitive function prior to surgery. However, little is known regarding the factors that are associated with pre-bypass cognitive function. A battery of neuropsychological tests was administered to a group of patients listed for bypass surgery (n = 109). Medical, sociodemographic and emotional predictors of cognitive function were investigated using structural equation modeling. Medical factors, namely history of hypertension and low ejection fraction, significantly predicted reduced cognitive function, as did several sociodemographic characteristics, namely older age, less education, non-English speaking background, manual occupation, and male gender. One emotional variable, confusion and bewilderment, was also a significant predictor whereas anxiety and depression were not. When significant predictors from the three sets of variables were included in a combined model, three of the five sociodemographic characteristics, namely age, non-English speaking background and occupation, and the two medical factors remained significant. Apart from sociodemographic characteristics, medical factors such as a history of hypertension and low ejection fraction significantly predicted reduced cognitive function in bypass candidates prior to surgery.