Testing the large genome constraint hypothesis in tropical rhizomatous herbs: life strategies, plant traits and habitat preferences in gingers

Plant species with large genomes tend to be excluded from climatically more extreme environments with a shorter growing season. Species that occupy such environments are assumed to be under natural selection for more rapid growth and smaller genome size (GS). However, evidence for this is available only for temperate organisms. Here, we study the evolution of GS in two subfamilies of the tropical family Zingiberaceae to find out whether species with larger genomes are confined to environments where the vegetative season is longer. We tested our hypothesis on 337 ginger species from regions with contrasting climates by correlating their GS with an array of plant traits and environmental variables. We revealed 16-fold variation in GS which was tightly related to shoot seasonality. Negative correlations of GS with latitude, temperature and precipitation emerged in the subfamily Zingiberoidae, demonstrating that species with larger GS are excluded from areas with a shorter growing season. In the subfamily Alpinioideae, GS turned out to be correlated with the type of stem and light requirements and its members cope with seasonality mainly by adaptation to shady and moist habitats. The Ornstein-Uhlenbeck models suggested that evolution in regions with humid climates favoured larger GS than in drier regions. Our results indicate that climate seasonality exerts an upper constraint on GS not only in temperate regions but also in the tropics, unless species with large genomes find alternative ways to escape from that constraint.

A Draft Genome of the Ginger Species Alpinia nigra and New Insights into the Genetic Basis of Flexistyly

Angiosperms possess various strategies to ensure reproductive success, such as stylar polymorphisms that encourage outcrossing. Here, we investigate the genetic basis of one such dimorphism that combines both temporal and spatial separation of sexual function, termed flexistyly. It is a floral strategy characterised by the presence of two morphs that differ in the timing of stylar movement. We performed a de novo assembly of the genome of Alpinia nigra using high-depth genomic sequencing. We then used Pool-seq to identify candidate regions for flexistyly based on allele frequency or coverage differences between pools of anaflexistylous and cataflexistylous morphs. The final genome assembly size was 2 Gb, and showed no evidence of recent polyploidy. The Pool-seq did not reveal large regions with high FST values, suggesting large structural chromosomal polymorphisms are unlikely to underlie differences between morphs. Similarly, no region had a 1:2 mapping depth ratio which would be indicative of hemizygosity. We propose that flexistyly is governed by a small genomic region that might be difficult to detect with Pool-seq, or a complex genomic region that proved difficult to assemble. Our genome will be a valuable resource for future studies of gingers, and provides the first steps towards characterising this complex floral phenotype.

Intravenous Lidocaine Does Not Improve Neurologic Outcomes after Cardiac Surgery: A Randomized Controlled Trial

BACKGROUND

Cognitive decline after cardiac surgery occurs frequently and persists in a significant proportion of patients. Preclinical studies and human trials suggest that intravenous lidocaine may confer protection in the setting of neurologic injury. It was hypothesized that lidocaine administration would reduce cognitive decline after cardiac surgery compared to placebo.

METHODS

After institutional review board approval, 478 patients undergoing cardiac surgery were enrolled into this multicenter, prospective, randomized, double-blinded, placebo-controlled, parallel group trial. Subjects were randomized to lidocaine 1 mg/kg bolus after the induction of anesthesia followed by a continuous infusion (48 μg · kg · min for the first hour, 24 μg · kg · min for the second hour, and 10 μg · kg · min for the next 46 h) or saline with identical volume and rate changes to preserve blinding. Cognitive function was assessed preoperatively and at 6 weeks and 1 yr postoperatively using a standard neurocognitive test battery. The primary outcome was change in cognitive function between baseline and 6 weeks postoperatively, adjusting for age, years of education, baseline cognition, race, and procedure type.

RESULTS

Among the 420 allocated subjects who returned for 6-week follow-up (lidocaine: N = 211; placebo: N = 209), there was no difference in the continuous cognitive score change (adjusted mean difference [95% CI], 0.02 (-0.05, 0.08); P = 0.626). Cognitive deficit (greater than 1 SD decline in at least one cognitive domain) at 6 weeks occurred in 41% (87 of 211) in the lidocaine group versus 40% (83 of 209) in the placebo group (adjusted odds ratio [95% CI], 0.94 [0.63, 1.41]; P = 0.766). There were no differences in any quality of life outcomes between treatment groups. At the 1-yr follow-up, there continued to be no difference in cognitive score change, cognitive deficit, or quality of life.

CONCLUSIONS

Intravenous lidocaine administered during and after cardiac surgery did not reduce postoperative cognitive decline at 6 weeks.

Securing a Network for a Research-Intensive, Referral Academic Medical Center: University of Kentucky HealthCare as a Case Study

Over the last 15 years, UK HealthCare, the clinical enterprise of the University of Kentucky, has undertaken 3 clinical strategic plans to secure its position as a research-intensive, referral academic medical center. The first plan, titled Securing the Traditional Marketplace (2005-2010), focused on building advanced subspecialty programs on campus while pursuing partnerships with providers in UK HealthCare's traditional marketplace, eastern Kentucky. The second plan, Expanding the Footprint (2010-2015), recognized that UK HealthCare needed to cover a population base of 5 to 10 million people to support its subspecialty programs. These 2 strategic plans were successful and achieved 4 outcomes: a doubling of annual discharges, a dramatic increase of transfers/external referrals, a significant increase in the case mix index, and impressive growth in subspecialty programs. The third clinical strategic plan, Preparing for Change (2015-2020), has expanded UK HealthCare's gains in the face of rapidly changing reimbursement systems and delivery models. The pillars of this plan are responding to consumerism, strengthening hallmark programs through service lines, "hard wiring" relationships with partnering organizations including establishing the Kentucky Health Collaborative, and building infrastructure to deal with risk-based reimbursement. UK HealthCare is trying to spearhead a rational system of care for Kentucky rather than a system that rations care. Halfway through the third clinical strategic plan, UK HealthCare has seen increased discharges, transfers, and clinical expansion in its hallmark programs, building evidence that well-thought business practices can lead to improved public policy.

First molecular phylogenetic insights into the evolution of Eriocaulon (Eriocaulaceae, Poales)

Eriocaulon is a genus of c. 470 aquatic and wetland species of the monocot plant family Eriocaulaceae. It is widely distributed in Africa, Asia and America, with centres of species richness in the tropics. Most species of Eriocaulon grow in wetlands although some inhabit shallow rivers and streams with an apparent adaptive morphology of elongated submerged stems. In a previous molecular phylogenetic hypothesis, Eriocaulon was recovered as sister of the African endemic genus Mesanthemum. Several regional infrageneric classifications have been proposed for Eriocaulon. This study aims to critically assess the existing infrageneric classifications through phylogenetic reconstruction of infrageneric relationships, based on DNA sequence data of four chloroplast markers and one nuclear marker. There is little congruence between our molecular results and previous morphology-based infrageneric classifications. However, some similarities can be found, including Fyson's sect. Leucantherae and Zhang's sect. Apoda. Further phylogenetic studies, particularly focusing on less well sampled regions such as the Neotropics, will help provide a more global overview of the relationships in Eriocaulon and may enable suggesting the first global infrageneric classification.

Typification of names in Kaempferia (Zingiberaceae) in the flora of Cambodia, Laos and Vietnam

Neotypes are designated for five names in Kaempferia (Zingiberaceae) from Lao PDR, namely K.attapeuensis Picheans. & Koonterm, K.champasakensis Picheans. & Koonterm, K.gigantiphylla Picheans. & Koonterm, K.sawanensis Picheans. & Koonterm and K.xiengkhouangensis Picheans. & Phokham.

Neurocognitive Function after Cardiac Surgery: From Phenotypes to Mechanisms

For half a century, it has been known that some patients experience neurocognitive dysfunction after cardiac surgery; however, defining its incidence, course, and causes remains challenging and controversial. Various terms have been used to describe neurocognitive dysfunction at different times after cardiac surgery, ranging from "postoperative delirium" to "postoperative cognitive dysfunction or decline." Delirium is a clinical diagnosis included in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Postoperative cognitive dysfunction is not included in the DSM-5 and has been heterogeneously defined, though a recent international nomenclature effort has proposed standardized definitions for it. Here, the authors discuss pathophysiologic mechanisms that may underlie these complications, review the literature on methods to prevent them, and discuss novel approaches to understand their etiology that may lead to novel treatment strategies. Future studies should measure both delirium and postoperative cognitive dysfunction to help clarify the relationship between these important postoperative complications.

Longitudinal Changes in Regional Cerebral Perfusion and Cognition After Cardiac Operation

BACKGROUND

Cardiac operation has been associated with increased risk of postoperative cognitive decline, as well as dementia risk in the general population. Few studies, however, have examined the impact of coronary revascularization or valve replacement or repair operation on longitudinal cerebral perfusion changes or their association with cognitive function.

METHODS

We examined longitudinal changes in cerebral perfusion among 54 individuals with cardiac disease; 27 undergoing cardiac operation and 27 matched control patients. Arterial spin labeling magnetic resonance perfusion imaging was used to quantify cerebral blood flow within the anterior communicating artery, middle cerebral artery (MCA), and posterior communicating artery vascular territories before operation and postoperatively at 6 weeks and 1 year. Cognitive performance was examined during the same intervals by using a battery of tests that tapped memory, executive, information processing and upper extremity motor functions. Repeated measures, mixed models were used to examine for perfusion changes and the association between perfusion changes and cognition.

RESULTS

Significant postoperative increases in perfusion were observed at 6 weeks within the MCA vascular territory after cardiac operation (p = 0.035 for interaction). Perfusion changes were most notable in distal territories of the MCA and posterior communicating artery at 6 weeks, with no additional changes at 1 year. Postoperative increases in MCA perfusion at 6 weeks were associated with improved psychomotor speed (β = 0.35, p = 0.016), whereas no important differences were found between the groups in vascular territory perfusion and cognition at 1 year.

CONCLUSIONS

Cardiac operation is associated with important short-term increases in MCA perfusion with associated improvements in psychomotor speed.

Dual antiplatelet therapy for perioperative myocardial infarction following CABG surgery

OBJECTIVES

Perioperative myocardial infarction (MI) after coronary artery bypass graft surgery (CABG) has been associated with adverse outcome. Whether perioperative MI should be treated with dual antiplatelet therapy (DAPT) is unknown. We compared the effect of DAPT versus aspirin alone on short-term outcomes among patients with perioperative MI following CABG.

METHODS

We used data from 3 clinical trials that enrolled patients undergoing isolated CABG: PREVENT IV (2002-2003), MEND-CABG II (2004-2005), and RED-CABG (2009-2010) (n = 9117). Perioperative MI was defined as CK-MB >5 times the upper limit of normal within 24 h of surgery (n = 2052). DAPT was defined as DAPT given after surgery and prior to discharge. A Cox regression model was used to assess the association between DAPT and 30-day nonfatal MI, stroke, or mortality after adjustment for baseline covariates.

RESULTS

DAPT (n = 527) and aspirin alone (n = 1525) cohorts were similar in baseline comorbidities. Off pump bypass was used in 5.2% (n = 106) of patients. There was no difference in the 30-day composite of death, MI or stroke between patients receiving DAPT versus aspirin alone, nor in any of the individual components. There were fewer all-cause re-hospitalizations at 30 days following surgery among patients in the DAPT group (adjusted HR 0.71, CI 0.52-0.97, P = .033).

CONCLUSION

One-quarter of CABG patients who had perioperative MI were treated with DAPT. DAPT was not associated with a difference in MI, stroke, or mortality at 30 days, but was associated with fewer re-hospitalizations. Further studies are needed to determine the optimal antiplatelet regimen following perioperative MI. What is already known about this subject? Perioperative myocardial infarction portends poor outcome but optimal management is currently unclear. While dual antiplatelet therapy is standard of care for acute coronary syndrome, its role in perioperative myocardial infarction is unknown. What does this study add? Dual antiplatelet therapy use during perioperative myocardial infarction was not associated with a difference in myocardial infarction, stroke or mortality at 30 days. It was, however, associated with fewer re-hospitalizations at 30 days. How might this impact on clinical practice? Dual antiplatelet therapy may be a potential treatment option for perioperative myocardial infarction after CABG surgery. Further studies are needed to better understand treatment for this disease process.

Task-related changes in degree centrality and local coherence of the posterior cingulate cortex after major cardiac surgery in older adults

OBJECTIVES

Older adults often display postoperative cognitive decline (POCD) after surgery, yet it is unclear to what extent functional connectivity (FC) alterations may underlie these deficits. We examined for postoperative voxel-wise FC changes in response to increased working memory load demands in cardiac surgery patients and nonsurgical controls.

EXPERIMENTAL DESIGN

Older cardiac surgery patients (n = 25) completed a verbal N-back working memory task during MRI scanning and cognitive testing before and 6 weeks after surgery; nonsurgical controls with cardiac disease (n = 26) underwent these assessments at identical time intervals. We measured postoperative changes in degree centrality, the number of edges attached to a brain node, and local coherence, the temporal homogeneity of regional functional correlations, using voxel-wise graph theory-based FC metrics. Group × time differences were evaluated in these FC metrics associated with increased N-back working memory load (2-back > 1-back), using a two-stage partitioned variance, mixed ANCOVA.

PRINCIPAL OBSERVATIONS

Cardiac surgery patients demonstrated postoperative working memory load-related degree centrality increases in the left dorsal posterior cingulate cortex (dPCC; p < .001, cluster p-FWE < .05). The dPCC also showed a postoperative increase in working memory load-associated local coherence (p < .001, cluster p-FWE < .05). dPCC degree centrality and local coherence increases were inversely associated with global cognitive change in surgery patients (p < .01), but not in controls.

CONCLUSIONS

Cardiac surgery patients showed postoperative increases in working memory load-associated degree centrality and local coherence of the dPCC that were inversely associated with postoperative global cognitive outcomes and independent of perioperative cerebrovascular damage.

The Effect of Propofol vs. Isoflurane Anesthesia on Postoperative Changes in Cerebrospinal Fluid Cytokine Levels: Results from a Randomized Trial

Introduction

Aside from direct effects on neurotransmission, inhaled and intravenous anesthetics have immunomodulatory properties. In vitro and mouse model studies suggest that propofol inhibits, while isoflurane increases, neuroinflammation. If these findings translate to humans, they could be clinically important since neuroinflammation has detrimental effects on neurocognitive function in numerous disease states.

Materials and methods

To examine whether propofol and isoflurane differentially modulate neuroinflammation in humans, cytokines were measured in a secondary analysis of cerebrospinal fluid (CSF) samples from patients prospectively randomized to receive anesthetic maintenance with propofol vs. isoflurane (registered with http://www.clinicaltrials.gov, identifier NCT01640275). We measured CSF levels of EGF, eotaxin, G-CSF, GM-CSF, IFN-α2, IL-1RA, IL-6, IL-7, IL-8, IL-10, IP-10, MCP-1, MIP-1α, MIP-1β, and TNF-α before and 24 h after intracranial surgery in these study patients.

Results

After Bonferroni correction for multiple comparisons, we found significant increases from before to 24 h after surgery in G-CSF, IL-10, IL-1RA, IL-6, IL-8, IP-10, MCP-1, MIP-1α, MIP-1β, and TNF-α. However, we found no difference in cytokine levels at baseline or 24 h after surgery between propofol- (n = 19) and isoflurane-treated (n = 21) patients (p > 0.05 for all comparisons). Increases in CSF IL-6, IL-8, IP-10, and MCP-1 levels directly correlated with each other and with postoperative CSF elevations in tau, a neural injury biomarker. We observed CSF cytokine increases up to 10-fold higher after intracranial surgery than previously reported after other types of surgery.

Discussion

These data clarify the magnitude of neuroinflammation after intracranial surgery, and raise the possibility that a coordinated neuroinflammatory response may play a role in neural injury after surgery.

The Effect of Propofol Versus Isoflurane Anesthesia on Human Cerebrospinal Fluid Markers of Alzheimer's Disease: Results of a Randomized Trial

BACKGROUND

Preclinical studies have found differential effects of isoflurane and propofol on the Alzheimer's disease (AD)-associated markers tau, phosphorylated tau (p-tau) and amyloid-β (Aβ).

OBJECTIVE

We asked whether isoflurane and propofol have differential effects on the tau/Aβ ratio (the primary outcome), and individual AD biomarkers. We also examined whether genetic/intraoperative factors influenced perioperative changes in AD biomarkers.

METHODS

Patients undergoing neurosurgical/otolaryngology procedures requiring lumbar cerebrospinal fluid (CSF) drain placement were prospectively randomized to receive isoflurane (n = 21) or propofol (n = 18) for anesthetic maintenance. We measured perioperative CSF sample AD markers, performed genotyping assays, and examined intraoperative data from the electronic anesthesia record. A repeated measures ANOVA was used to examine changes in AD markers by anesthetic type over time.

RESULTS

The CSF tau/Aβ ratio did not differ between isoflurane- versus propofol-treated patients (p = 1.000). CSF tau/Aβ ratio and tau levels increased 10 and 24 h after drain placement (p = 2.002×10-6 and p = 1.985×10-6, respectively), mean CSF p-tau levels decreased (p = 0.005), and Aβ levels did not change (p = 0.152). There was no interaction between anesthetic treatment and time for any of these biomarkers. None of the examined genetic polymorphisms, including ApoE4, were associated with tau increase (n = 9 polymorphisms, p > 0.05 for all associations).

CONCLUSION

Neurosurgery/otolaryngology procedures are associated with an increase in the CSF tau/Aβ ratio, and this increase was not influenced by anesthetic type. The increased CSF tau/Aβ ratio was largely driven by increases in tau levels. Future work should determine the functional/prognostic significance of these perioperative CSF tau elevations.

Resting-State Functional Connectivity and Cognition After Major Cardiac Surgery in Older Adults without Preoperative Cognitive Impairment: Preliminary Findings

OBJECTIVES

To look for changes in intrinsic functional brain connectivity associated with postoperative changes in cognition, a common complication in seniors undergoing major surgery, using resting-state functional magnetic resonance imaging.

DESIGN

Objective cognitive testing and functional brain imaging were prospectively performed at preoperative baseline and 6 weeks after surgery and at the same time intervals in nonsurgical controls.

SETTING

Academic medical center.

PARTICIPANTS

Older adults undergoing cardiac surgery (n = 12) and nonsurgical older adult controls with a history of coronary artery disease (n = 12); no participants had cognitive impairment at preoperative baseline (Mini-Mental State Examination score >27).

MEASUREMENTS

Differences in resting-state functional connectivity (RSFC) and global cognitive change relationships were assessed using a voxel-wise intrinsic connectivity method, controlling for demographic factors and pre- and perioperative cerebral white matter disease volume. Analyses were corrected for multiple comparisons (false discovery rate P < .01).

RESULTS

Global cognitive change after cardiac surgery was significantly associated with intrinsic RSFC changes in regions of the posterior cingulate cortex and right superior frontal gyrus-anatomical and functional locations of the brain's default mode network (DMN). No statistically significant relationships were found between global cognitive change and RSFC change in nonsurgical controls.

CONCLUSION

Clinicians have long known that some older adults develop postoperative cognitive dysfunction (POCD) after anesthesia and surgery, yet the neurobiological correlates of POCD are not well defined. The current results suggest that altered RSFC in specific DMN regions is positively correlated with global cognitive change 6 weeks after cardiac surgery, suggesting that DMN activity and connectivity could be important diagnostic markers of POCD or intervention targets for potential POCD treatment efforts.

Strategies to Protect the Brain During Cardiac Surgery

Despite significant advances in cardiopulmonary by pass (CPB) technology, surgical techniques, and anes thetic management, central nervous system (CNS) com plications remain a common and costly problem after CPB. Stroke is often considered a rare and unprevent able complication of cardiac surgery. Recent studies have shown that through the use of echocardiography and historical risk stratification strategies, we can de fine which patients are at substantially greater risk for CNS injury. Through enhanced understanding of the etiology of stroke and perioperative factors, which are associated with potential for neuroprotection or injury extension, there now exists a greater potential than ever to substantially reduce neurological injury associ ated with cardiac surgery. Strategies and theories of stratifying patients at risk and secondarily reducing that risk are described, as well as consideration for early postoperative assessment to allow treatment when events occur.

Genetic Predictors of Perioperative Neurologic and Neuropsychological Injury and Recovery

Central nervous system (CNS) dysfunction after cardio pulmonary bypass represents a continuum from coma and focal stroke to cognitive deficits after surgery. Despite the marked increase in investigation of neuro logic and neurocognitive deficits after cardiac surgery, causative factors fail to predict the majority of the variance in the observed incidence of both early and late neurocognitive decline pointing to some inherent indi vidual susceptibility to injury. The authors' investigative team recently discovered a genetic association be tween late-onset Alzheimer's disease and the apolipo protein E (APOE, gene; apoE, protein) ∈-4 gene. This finding triggered many recent studies that have shown an important role of apoE in the determination of neurologic injury and recovery following a variety of acute ischemic insults including intracerebral hemor rhage, closed-head injury, as well as acute stroke and dementia pugilistica. Most important to the current discussion is the authors' recent report documenting preliminary evidence of an association of APOE4 with neurocognitive decline after cardiac surgery. This re view discusses the authors' hypothesis that the bio chemical products coded by this gene are not available to protect and repair the neurons of the CNS during cardiac surgery resulting in deficits of memory, atten tion, and concentration. Potential mechanisms of apoE's association with acute neurologic injury are discussed including regulation of the inflammatory response. The authors have recently determined that apoE, in vivo, modulates the release of nitric oxide and tumor necro sis factor a. This may compound the autonomic dysreg ulation recently reported in the aging population. The authors' preliminary data associating APOE4 with cogni tive impairment after cardiac surgery support this hy pothesis. The different potential mechanisms of apoE function in neuronal injury and recovery are not mutu ally exclusive, and it is likely that apoE modulates the CNS injury response at several functional levels.

Gene signatures of postoperative atrial fibrillation in atrial tissue after coronary artery bypass grafting surgery in patients receiving β-blockers

Atrial tissue gene expression profiling may help to determine how differentially expressed genes in the human atrium before cardiopulmonary bypass (CPB) are related to subsequent biologic pathway activation patterns, and whether specific expression profiles are associated with an increased risk for postoperative atrial fibrillation (AF) or altered response to β-blocker (BB) therapy after coronary artery bypass grafting (CABG) surgery. Right atrial appendage (RAA) samples were collected from 45 patients who were receiving perioperative BB treatment, and underwent CABG surgery. The isolated RNA samples were used for microarray gene expression analysis, to identify probes that were expressed differently in patients with and without postoperative AF. Gene expression analysis was performed to identify probes that were expressed differently in patients with and without postoperative AF. Gene set enrichment analysis (GSEA) was performed to determine how sets of genes might be systematically altered in patients with postoperative AF. Of the 45 patients studied, genomic DNA from 42 patients was used for target sequencing of 66 candidate genes potentially associated with AF, and 2,144 single-nucleotide polymorphisms (SNPs) were identified. We then performed expression quantitative trait loci (eQTL) analysis to determine the correlation between SNPs identified in the genotyped patients, and RAA expression. Probes that met a false discovery rate<0.25 were selected for eQTL analysis. Of the 17,678 gene expression probes analyzed, 2 probes met our prespecified significance threshold of false discovery rate<0.25. The most significant probe corresponded to vesicular overexpressed in cancer - prosurvival protein 1 gene (VOPP1; 1.83 fold change; P=3.47×10(-7)), and was up-regulated in patients with postoperative AF, whereas the second most significant probe, which corresponded to the LOC389286 gene (0.49 fold change; P=1.54×10(-5)), was down-regulated in patients with postoperative AF. GSEA highlighted the role of VOPP1 in pathways with biologic relevance to myocardial homeostasis, and oxidative stress and redox modulation. Candidate gene eQTL showed a trans-acting association between variants of G protein-coupled receptor kinase 5 gene, previously linked to altered BB response, and high expression of VOPP1. In patients undergoing CABG surgery, RAA gene expression profiling, and pathway and eQTL analysis suggested that VOPP1 plays a novel etiological role in postoperative AF despite perioperative BB therapy.

Intraoperative Magnesium Administration Does Not Reduce Postoperative Atrial Fibrillation After Cardiac Surgery

BACKGROUND

Hypomagnesemia has been associated with an increased risk of postoperative atrial fibrillation (POAF). Although previous studies have suggested a beneficial effect of magnesium (Mg) therapy, almost all of these are limited by small sample size and relatively low Mg dose. We hypothesized that high-dose Mg decreases the occurrence of new-onset POAF, and we tested this hypothesis by using data from a prospective trial that assessed the effect of Mg on cognitive outcomes in patients undergoing cardiac surgery.

METHODS

A total of 389 patients undergoing cardiac surgery were enrolled in this double-blind, placebo-controlled trial. Subjects were randomized to receive Mg as a 50-mg/kg bolus immediately after induction of anesthesia followed by another 50 mg/kg as an infusion given over 3 hours (total dose, 100 mg/kg) or placebo. We tested the effect of Mg therapy on POAF with logistic regression, adjusting for the risk of atrial fibrillation (AF) by using the Multicenter Study of Perioperative Ischemia risk index for Atrial Fibrillation after Cardiac Surgery.

RESULTS

Among the 363 patients analyzed, after we excluded patients with chronic or acute preoperative AF (placebo: n = 177; Mg: n = 186), the incidence of new-onset POAF was 42.5% (95% confidence interval [CI], 35%-50%) in the Mg group compared with 37.9% (95% CI, 31%-45%) in the placebo group (P = 0.40). The 95% CI for this absolute risk difference of 4.6% is -5.5% to 14.7%. The time to onset of POAF also was identical between the groups, and no significant effect of Mg was found in logistic regression analysis after we adjusted for AF risk (odds ratio, 1.09; 95% CI, 0.69-1.72; P = 0.73).

CONCLUSIONS

High-dose intraoperative Mg therapy did not decrease the incidence of new-onset POAF after cardiac surgery.

Genome-wide association study of new-onset atrial fibrillation after coronary artery bypass grafting surgery

BACKGROUND

Postoperative atrial fibrillation (AF) is a potentially life-threatening complication after coronary artery bypass graft (CABG) surgery. Genetic predisposition may predict risk for developing postoperative AF.

METHODS

Study subjects underwent CABG surgery with cardiopulmonary bypass at Duke University Medical Center. In a discovery cohort of 877 individuals from the Perioperative Genetics and Safety Outcomes Study, we performed a genome-wide association study using a logistic regression model with a covariate adjustment for AF risk index. Single-nucleotide polymorphisms (SNPs) that met a P < 5 × 10(-5) were further tested using a replication dataset of 304 individuals from the CATHeterization GENetics biorepository, followed by meta-analysis. Potential pathways related to postoperative AF were identified through gene enrichment analysis using the top genome-wide association study SNPs (P < 10(-4)).

RESULTS

Nineteen SNPs met the a priori defined discovery threshold for replication, but only 3 met nominal significance (P < .05) in the CATHeterization GENetics group, with only one-rs10504554, in the intronic region in lymphocyte antigen 96 (LY96)-showing the same direction of the effect for postoperative AF (odds ratio [OR] 0.48, 95% CI 0.34-0.68, P = 2.9 × 10(-5) vs OR 0.55, 95% CI 0.31-0.99, P = .046) and strong overall association by meta-analysis (meta-P = 4.0 × 10(-6)). Gene enrichment analysis highlighted the role of LY96 in pathways of biologic relevance to activation and modulation of innate immune responses. Our analysis also showed potential association between LY96 and nuclear factor κ-B interaction and postoperative AF through their relevance to inflammatory signaling pathways.

CONCLUSIONS

In patients undergoing CABG surgery, we found genetic polymorphisms in LY96 associated with decreased risk of postoperative AF.

Genome-wide association study of acute kidney injury after coronary bypass graft surgery identifies susceptibility loci

Acute kidney injury (AKI) is a common, serious complication of cardiac surgery. Since prior studies have supported a genetic basis for postoperative AKI, we conducted a genome-wide association study (GWAS) for AKI following coronary bypass graft (CABG) surgery. The discovery dataset consisted of 873 non-emergent CABG surgery patients with cardiopulmonary bypass (PEGASUS), while a replication dataset had 380 cardiac surgical patients (CATHGEN). Single nucleotide polymorphism (SNP) data were based on Illumina Human610-Quad (PEGASUS) and OMNI1-Quad (CATHGEN) BeadChips. We used linear regression with adjustment for a clinical AKI risk score to test SNP associations with the postoperative peak rise relative to preoperative serum creatinine concentration as a quantitative AKI trait. Nine SNPs meeting significance in the discovery set were detected. The rs13317787 in GRM7|LMCD1-AS1 intergenic region (3p21.6) and rs10262995 in BBS9 (7p14.3) were replicated with significance in the CATHGEN data set and exhibited significantly strong overall association following meta-analysis. Additional fine-mapping using imputed SNPs across these two regions and meta-analysis found genome wide significance at the GRM7|LMCD1-AS1 locus and a significantly strong association at BBS9. Thus, through an unbiased GWAS approach, we found two new loci associated with post-CABG AKI providing new insights into the pathogenesis of perioperative AKI.

Genome-wide association study of perioperative myocardial infarction after coronary artery bypass surgery

OBJECTIVES

Identification of patient subpopulations susceptible to develop myocardial infarction (MI) or, conversely, those displaying either intrinsic cardioprotective phenotypes or highly responsive to protective interventions remain high-priority knowledge gaps. We sought to identify novel common genetic variants associated with perioperative MI in patients undergoing coronary artery bypass grafting using genome-wide association methodology.

SETTING

107 secondary and tertiary cardiac surgery centres across the USA.

PARTICIPANTS

We conducted a stage I genome-wide association study (GWAS) in 1433 ethnically diverse patients of both genders (112 cases/1321 controls) from the Genetics of Myocardial Adverse Outcomes and Graft Failure (GeneMAGIC) study, and a stage II analysis in an expanded population of 2055 patients (225 cases/1830 controls) combined from the GeneMAGIC and Duke Perioperative Genetics and Safety Outcomes (PEGASUS) studies. Patients undergoing primary non-emergent coronary bypass grafting were included.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome variable was perioperative MI, defined as creatine kinase MB isoenzyme (CK-MB) values ≥10× upper limit of normal during the first postoperative day, and not attributable to preoperative MI. Secondary outcomes included postoperative CK-MB as a quantitative trait, or a dichotomised phenotype based on extreme quartiles of the CK-MB distribution.

RESULTS

Following quality control and adjustment for clinical covariates, we identified 521 single nucleotide polymorphisms in the stage I GWAS analysis. Among these, 8 common variants in 3 genes or intergenic regions met p<10(-5) in stage II. A secondary analysis using CK-MB as a quantitative trait (minimum p=1.26×10(-3) for rs609418), or a dichotomised phenotype based on extreme CK-MB values (minimum p=7.72×10(-6) for rs4834703) supported these findings. Pathway analysis revealed that genes harbouring top-scoring variants cluster in pathways of biological relevance to extracellular matrix remodelling, endoplasmic reticulum-to-Golgi transport and inflammation.

CONCLUSIONS

Using a two-stage GWAS and pathway analysis, we identified and prioritised several potential susceptibility loci for perioperative MI.

Emission of methane, carbon monoxide, carbon dioxide and short-chain hydrocarbons from vegetation foliage under ultraviolet irradiation

The original report that plants emit methane (CH4 ) under aerobic conditions caused much debate and controversy. Critics questioned experimental techniques, possible mechanisms for CH4 production and the nature of estimating global emissions. Several studies have now confirmed that aerobic CH4 emissions can be detected from plant foliage but the extent of the phenomenon in plants and the precise mechanisms and precursors involved remain uncertain. In this study, we investigated the role of environmentally realistic levels of ultraviolet (UV) radiation in causing the emission of CH4 and other gases from foliage obtained from a wide variety of plant types. We related our measured emissions to the foliar content of methyl esters and lignin and to the epidermal UV absorbance of the species investigated. Our data demonstrate that the terrestrial vegetation foliage sampled did emit CH4 , with a range in emissions of 0.6-31.8 ng CH4  g(-1) leaf DW h(-1) , which compares favourably with the original reports of experimental work. In addition to CH4 emissions, our data show that carbon monoxide, ethene and propane are also emitted under UV stress but we detected no significant emissions of carbon dioxide or ethane.

Apolipoprotein epsilon 4 genotype is associated with less improvement in cognitive function five years after cardiac surgery: a retrospective cohort study

PURPOSE

Cognitive performance after cardiac surgery can be impaired, and genetic risk factors have previously been suggested. When compared with other isoforms of the gene, the apolipoprotein epsilon 4 (APOE4) allele is associated with worse outcomes in many neurologic disorders. We hypothesized that the APOE4 allele is associated with less favourable cognitive function five years after surgery.

METHODS

Caucasian patients enrolled in previously reported prospective cognitive trials in both cardiac and non-cardiac surgery participated in this retrospective cohort study. Neuropsychological function was assessed at baseline and five years postoperatively. The relationship between change in cognitive index score and APOE was evaluated using multivariable linear regression. An additive genetic model toward the epsilon 4 allele was applied with adjustment for baseline cognition, years of education, age, presence of diabetes in both cohorts, and presence of coronary artery disease in the non-cardiac surgery cohort.

RESULTS

A total of 357 patients were included in this study. In the cardiac surgery group (n = 233), baseline cognitive index (P < 0.001), years of education (P = 0.04), age at time of surgery (P < 0.001), and the APOE4 allele (P = 0.009), were associated with a five-year change in cognitive index. Patients carrying the APOE4 allele showed less improvement in cognitive index scores five years after cardiac surgery compared with patients without the APOE4 allele. In the non-cardiac surgery (n = 124) group, no association was found between APOE4 allele status and change in cognitive index.

CONCLUSION

We report an association between APOE4 and neurocognitive function five years following cardiac surgery. Preoperative identification of patients with the APOE4 genotype may improve stratification of cardiac surgery patients at risk for a less favourable cognitive trajectory.

G protein-coupled receptor kinase 5 gene polymorphisms are associated with postoperative atrial fibrillation after coronary artery bypass grafting in patients receiving β-blockers

BACKGROUND

We hypothesized that genetic variations in the adrenergic signaling pathway and cytochrome P450 2D6 enzyme are associated with new-onset atrial fibrillation (AF) in patients who underwent coronary artery bypass grafting and were treated with perioperative β-blockers (BBs).

METHODS AND RESULTS

Two cohorts of patients who underwent coronary artery bypass grafting and received perioperative BBs at Duke University Medical Center were studied. In a discovery cohort of 563 individuals from the Perioperative Genetics and Safety Outcomes Study (PEGASUS), using a covariate-adjusted logistic regression analysis, we tested 492 single-nucleotide polymorphisms (SNPs) in 10 candidate genes of the adrenergic signaling pathway and cytochrome P450 2D6 for association with postoperative AF despite perioperative BB therapy. SNPs meeting a false discovery rate ≤0.20 (P<0.002) were then tested in the replication cohort of 245 individuals from the Catheterization Genetics biorepository. Of the 492 SNPs examined, 4 intronic SNPs of the G protein-coupled kinase 5 (GRK5) gene were significantly associated with postoperative AF despite perioperative BB therapy in the discovery cohort with additive odds ratios between 1.72 and 2.75 (P=4.78×10(-5) to 0.0015). Three of these SNPs met nominal significance levels in the replication cohort with odds ratios between 2.07 and 2.60 (P=0.007 to 0.016). However, meta-analysis of the 2 data sets cohorts suggested strong association with postoperative AF despite perioperative BB therapy in all 4 SNPs (meta-P values from 1.66×10(-6) to 3.39×10(-5)).

CONCLUSIONS

In patients undergoing coronary artery bypass grafting, genetic variation in GRK5 is associated with postoperative AF despite perioperative BB therapy.

Neurological complications of cardiac surgery

As increasing numbers of elderly people undergo cardiac surgery, neurologists are frequently called upon to assess patients with neurological complications from the procedure. Some complications mandate acute intervention, whereas others need longer term observation and management. A large amount of published literature exists about these complications and guidance on best practice is constantly changing. Similarly, despite technological advances in surgical intervention and modifications in surgical technique to make cardiac procedures safer, these advances often create new avenues for neurological injury. Accordingly, rapid and precise neurological assessment and therapeutic intervention rests on a solid understanding of the evidence base and procedural variables.

The association of postcardiac surgery acute kidney injury with intraoperative systolic blood pressure hypotension

Background. Postoperative acute kidney injury (AKI) is associated with high mortality and substantial cost after aortocoronary bypass graft (CABG) surgery. We tested the hypothesis that intraoperative systolic blood pressure variation is associated with postoperative AKI. Methods. We gathered demographic, procedural, blood pressure, and renal outcome data for 7,247 CABG surgeries at a single institution between 1996 and 2005. A development/validation cohort methodology was randomly divided (66% and 33%, resp.). Peak postoperative serum creatinine rise relative to baseline (%ΔCr) was the primary AKI outcome variable. Markers reflective of intraoperative systolic blood pressure variation were derived for each patient including (1) peak and nadir values (absolute and relative to baseline) and (2) excursion episodes beyond selected thresholds (by duration, frequency, and duration × degree). Each marker of systolic blood pressure variation was then separately evaluated for association with AKI using linear regression models with adjustment for several known risk factors (age, aprotinin use, congestive heart failure, previous myocardial infarction, baseline creatinine, bypass time, diabetes, weight, concomitant valve surgery, gender, and preoperative pulse pressure). Results. An association was identified between systolic blood pressure relative to baseline and postoperative AKI (P < 0.006). Conclusions. In CABG surgery patients, intraoperative systolic blood pressure decrease relative to baseline systolic blood pressure is independently associated with postoperative AKI.

Intraoperative magnesium administration does not improve neurocognitive function after cardiac surgery

BACKGROUND AND PURPOSE

Neurocognitive decline occurs frequently after cardiac surgery and persists in a significant number of patients. Magnesium is thought to provide neuroprotection by preservation of cellular energy metabolism, blockade of the N-methyl-D-aspartate receptor, diminution of the inflammatory response, and inhibition of platelet activation. We therefore hypothesized that intraoperative magnesium administration would decrease postoperative cognitive impairment.

METHODS

After approval by the Duke University Health System Institutional Review Board, 389 patients undergoing cardiac surgery were enrolled in this prospective, randomized, double-blind, placebo-controlled clinical trial. Subjects were randomized to receive magnesium as a 50 mg/kg bolus followed by another 50 mg/kg infusion for 3 hours or placebo bolus and infusion. Cognitive function was assessed preoperatively and again at 6 weeks postoperatively using a standardized test battery. Mean CD11b fluorescence and percentage of platelets expressing CD62P, which are markers of leukocyte and platelet activation, respectively, were assessed by flow cytometry as a secondary outcome. The effect of magnesium on postoperative cognition was tested using multivariable regression modeling, adjusting for age, years of education, baseline cognition, sex, race, and weight.

RESULTS

Among the 389 allocated subjects (magnesium: n=198; placebo: n=191), the incidence of cognitive deficit in the magnesium group was 44.4% compared with 44.9% in the placebo group (P=0.93). The cognitive change score and platelet and leukocyte activation were also not different between the groups. Multivariable analysis revealed a marginal interaction between treatment group and weight such that heavier subjects receiving magnesium were less likely to have cognitive deficit (P=0.06).

CONCLUSIONS

Magnesium administered intravenously during cardiac surgery does not reduce postoperative cognitive dysfunction.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00041392.

Cortical β-amyloid levels and neurocognitive performance after cardiac surgery

INTRODUCTION

Neurological and neurocognitive dysfunction occurs frequently in the large number of increasingly elderly patients undergoing cardiac surgery every year. Perioperative cognitive deficits have been shown to persist after discharge and up to several years after surgery. More importantly, perioperative cognitive decline is predictive of long-term cognitive dysfunction, reduced quality of life and increased mortality. The proposed mechanisms to explain the cognitive decline associated with cardiac surgery include the neurotoxic accumulation of β-amyloid. This study will be the first to provide molecular imaging to assess the relationship between neocortical β-amyloid deposition and postoperative cognitive dysfunction.

METHODS AND ANALYSIS

40 patients providing informed consent for participation in this Institutional Review Board-approved study and undergoing cardiac (coronary artery bypass graft (CABG), valve or CABG+valve) surgery with cardiopulmonary bypass will be enrolled based on defined inclusion and exclusion criteria. At 6 weeks after surgery, participants will undergo (18)F-florbetapir positron emission tomography imaging to assess neocortical β-amyloid burden along with a standard neurocognitive battery and blood testing for apolipoprotein E ε-4 genotype.

RESULTS

The results will be compared to those of 40 elderly controls and 40 elderly patients with mild cognitive impairment who have previously completed (18)F-florbetapir imaging.

ETHICS AND DISSEMINATION

This study has been approved by the Duke University Institutional Review Board. The results will provide novel mechanistic insights into postoperative cognitive dysfunction that will inform future studies into potential treatments or preventative therapies of long-term cognitive decline after cardiac surgery.

Arterial hyperoxia during cardiopulmonary bypass and postoperative cognitive dysfunction

OBJECTIVE

To determine the effect of arterial normobaric hyperoxia during cardiopulmonary bypass (CPB) on postoperative neurocognitive function. The authors hypothesized that arterial hyperoxia during CPB is associated with neurocognitive decline at 6 weeks after cardiac surgery.

DESIGN

Retrospective study of patients undergoing cardiac surgery with CPB.

SETTING

A university hospital.

PARTICIPANTS

One thousand eighteen patients undergoing coronary artery bypass graft (CABG) or CABG + valve surgery with CPB who previously had been enrolled in prospective cognitive trials.

INTERVENTIONS

A battery of neurocognitive measures was administered at baseline and 6 weeks after surgery. Anesthetic and surgical care was managed as clinically indicated.

MEASUREMENTS AND MAIN RESULTS

Arterial hyperoxia was assessed primarily as the area under the curve (AUC) for the duration that PaO2 exceeded 200 mmHg during CPB and secondarily as the mean PaO2 during bypass, as a PaO2 = 300 mmHg at any point and as AUC>150 mmHg. Cognitive change was assessed both as a continuous change score and a dichotomous deficit rate. Multivariate regression accounting for age, years of education, baseline cognition, date of surgery, baseline postintubation PaO2, duration of CPB, and percent change in hematocrit level from baseline to lowest level during CPB revealed no significant association between hyperoxia during CPB and postoperative neurocognitive function.

CONCLUSIONS

Arterial hyperoxia during CPB was not associated with neurocognitive decline after 6 weeks in cardiac surgical patients.

Predictors of cognitive recovery after cardiac surgery

BACKGROUND

Postoperative neurocognitive decline occurs frequently. Although predictors of cognitive injury have been well examined, factors that modulate recovery have not. We sought to determine the predictors of cognitive recovery after initial injury following cardiac surgery.

METHODS

Two hundred eighty-one patients previously enrolled in cognitive studies who experienced cognitive decline 6 weeks after cardiac surgery were retrospectively evaluated. Eligible patients completed a battery of neurocognitive measures and quality-of-life assessments at baseline, 6 weeks, and 1 year after surgery. Factor analysis was conducted to calculate the cognitive index (CI), a unified, continuous measure of cognitive function. Cognitive recovery was defined as 1-year CI greater than baseline CI. Potential predictors of cognitive recovery including patient characteristics, quality-of-life factors, comorbidities, medications, and intraoperative variables were assessed with multivariable regression modeling; P<0.05 was considered significant.

RESULTS

Of the 229 patients in our final data set, 103 (45%) demonstrated cognitive recovery after initial decline in CI at 6 weeks. Multivariable analyses revealed that more education (odds ratio [OR] 1.332 [1.131-1.569], P<0.001), baseline CI (OR 0.987 [0.976-0.998], P=0.02), less decline in CI at 6 weeks (OR 1.044 [1.014-1.075], P=0.004), and greater activities of daily living at 6 weeks (OR 0.891 [0.810-0.981], P=0.02) were significant predictors of cognitive recovery.

CONCLUSION

Cognitive recovery occurred in approximately one half of the cardiac surgical patients experiencing early decline. The association between cognitive recovery and Instrumental Activities of Daily Living scores at 6 weeks merits further investigation as it is the only potentially modifiable predictor of recovery.

Effect of adenosine-regulating agent acadesine on morbidity and mortality associated with coronary artery bypass grafting: the RED-CABG randomized controlled trial

CONTEXT

Ischemia/reperfusion injury remains an important cause of morbidity and mortality after coronary artery bypass graft (CABG) surgery. In a meta-analysis of randomized controlled trials, perioperative and postoperative infusion of acadesine, a first-in-class adenosine-regulating agent, was associated with a reduction in early cardiac death, myocardial infarction, and combined adverse cardiac outcomes in participants undergoing on-pump CABG surgery.

OBJECTIVE

To assess the efficacy and safety of acadesine administered in the perioperative period in reducing all-cause mortality, nonfatal stroke, and severe left ventricular dysfunction (SLVD) through 28 days.

DESIGN, SETTING, AND PARTICIPANTS

The Reduction in Cardiovascular Events by Acadesine in Patients Undergoing CABG (RED-CABG) trial, a randomized, double-blind, placebo-controlled, parallel-group evaluation of intermediate- to high-risk patients (median age, 66 years) undergoing nonemergency, on-pump CABG surgery at 300 sites in 7 countries. Enrollment occurred from May 6, 2009, to July 30, 2010.

INTERVENTIONS

Eligible participants were randomized 1:1 to receive acadesine (0.1 mg/kg per minute for 7 hours) or placebo (both also added to cardioplegic solutions) beginning just before anesthesia induction.

MAIN OUTCOME MEASURE

Composite of all-cause mortality, nonfatal stroke, or need for mechanical support for SLVD during and following CABG surgery through postoperative day 28.

RESULTS

Because results of a prespecified futility analysis indicated a very low likelihood of a statistically significant efficacious outcome, the trial was stopped after 3080 of the originally projected 7500 study participants were randomized. The primary outcome occurred in 75 of 1493 participants (5.0%) in the placebo group and 76 of 1493 (5.1%) in the acadesine group (odds ratio, 1.01 [95% CI, 0.73-1.41]). There were no differences in key secondary end points measured.

CONCLUSION

In this population of intermediate- to high-risk patients undergoing CABG surgery, acadesine did not reduce the composite of all-cause mortality, nonfatal stroke, or SLVD.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00872001.

Thrombomodulin gene variants are associated with increased mortality after coronary artery bypass surgery in replicated analyses

BACKGROUND

We tested the hypothesis that genetic variation in thrombotic and inflammatory pathways is independently associated with long-term mortality after coronary artery bypass graft (CABG) surgery.

METHODS AND RESULTS

Two separate cohorts of patients undergoing CABG surgery at a single institution were examined, and all-cause mortality between 30 days and 5 years after the index CABG was ascertained from the National Death Index. In a discovery cohort of 1018 patients, a panel of 90 single-nucleotide polymorphisms (SNPs) in 49 candidate genes was tested with Cox proportional hazard models to identify clinical and genomic multivariate predictors of incident death. After adjustment for multiple comparisons and clinical predictors of mortality, the homozygote minor allele of a common variant in the thrombomodulin (THBD) gene (rs1042579) was independently associated with significantly increased risk of all-cause mortality (hazard ratio, 2.26; 95% CI, 1.31 to 3.92; P=0.003). Six tag SNPs in the THBD gene, 1 of which (rs3176123) in complete linkage disequilibrium with rs1042579, were then assessed in an independent validation cohort of 930 patients. After multivariate adjustment for the clinical predictors identified in the discovery cohort and multiple testing, the homozygote minor allele of rs3176123 independently predicted all-cause mortality (hazard ratio, 3.6; 95% CI, 1.67 to 7.78; P=0.001).

CONCLUSIONS

In 2 independent cardiac surgery cohorts, linked common allelic variants in the THBD gene are independently associated with increased long-term mortality risk after CABG and significantly improve the classification ability of traditional postoperative mortality prediction models.

Population pharmacokinetics of lidocaine administered during and after cardiac surgery

OBJECTIVE

The objective of this study was to determine the pharmacokinetics of lidocaine in a 48-hour infusion in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

DESIGN

A retrospective substudy of a clinical trial assessing the efficacy of intravenous lidocaine for postoperative cognitive decline.

SETTING

A university hospital.

PARTICIPANTS

Ninety-nine patients undergoing cardiac surgery with CPB.

INTERVENTIONS

After the induction of anesthesia, lidocaine was administered as a bolus of 1 mg/kg and followed by a continuous infusion at 4 mg/min for the 1st hour, 2 mg/min for the 2nd hour, and 1 mg/min for the next 46 hours.

MEASUREMENTS AND MAIN RESULTS

Blood samples were taken at baseline, the end of CPB, and 24 and 48 hours after CPB for the measurement of the plasma concentration of lidocaine. Lidocaine levels increased significantly over time despite a constant rate of infusion (p < 0.05). The pharmacokinetics of lidocaine was best described by a 2-compartment model, and body weight was found to be a significant factor for the volume of the central compartment and clearance. The final pharmacokinetic parameters were V(1)(L) = 0.0619*weight, V(2)(L) = 187, CL(1) (L/min) = 0.00419*weight, and CL(2) (L/min) = 8.92.

CONCLUSIONS

A 2-compartment pharmacokinetic model best describes the plasma concentrations of a 48-hour lidocaine infusion in patients undergoing cardiac surgery with CPB. The inclusion of body weight as a covariate on clearance and central compartment improves the model. Lidocaine infusions should be dosed by body weight and decreased after 24 hours to avoid potential toxicity in long-term infusions.

Storage age of transfused platelets and outcomes after cardiac surgery

BACKGROUND

The relationship between duration of platelet (PLT) storage, currently limited to 5days, and surgical outcomes has not been established. We tested the hypothesis that PLT storage age was associated with adverse outcomes.

STUDY DESIGN AND METHODS

A retrospective cohort of aortocoronary bypass (CABG) surgery patients from January 1996 to January 2005 receiving one or more PLT transfusions was selected for study. The composite primary ("short-term") outcome was 30-day mortality or prolonged hospital stay. Secondary outcomes included complications and survival to annual follow-up. Multivariable logistic regression models and Cox proportional hazards regression analysis evaluated the association between PLT storage age and outcomes, expressed as an odds ratio (OR) or hazard ratio with 95% confidence intervals (CIs), respectively.

RESULTS

PLT transfusion was administered to 3272 of 10,275 CABG patients and 2578 received units of known storage age, which ranged between 2 and 5days (median, 4days; 25th percentile, 3days; 75th percentile, 5 days). The mortality rate for the 1637 patients receiving a single plateletpheresis transfusion was 3.8%, while 21.6% experienced a prolonged hospital stay or death. After adjusting for the number of PLT and red blood cell (RBC) units transfused, RBC storage age, and preoperative mortality risk, there was no association between PLT storage age and short-term outcome (OR, 1.01; 95% CI, 0.90-1.14), survival (hazard ratio [HR], 1.04; 95% CI, 0.96-1.13), or postoperative infections.

CONCLUSIONS

PLT storage age was not associated with adverse short-term outcomes, decreased long-term survival, or infections after cardiac surgery.

Departures from the protocol during conduct of a clinical trial: a pattern from the data record consistent with a learning curve

OBJECTIVE

Recognition of learning curves in medical skill acquisition has enhanced patient safety through improved training techniques. Clinical trials research has not been similarly scrutinised. The VALsartan In Acute myocardial iNfarcTion, a large multinational, pragmatic, randomised, double-blind, multicentre trial, was retrospectively evaluated for evidence of research conduct consistent with a performance "learning curve".

DESIGN

Records provided protocol departure (deviations/violations) and documentation query data. For each site, analysis included patient order (eg, first, second), recruitment rate and first enrollment relative to study start date.

SETTING

Computerised data from a trial coordinated by an academic research organisation collaborating with 10 academic and 2 commercial research organisations and an industry sponsor. Interventions 931 sites enrolled 14,703 patients. Departures were restricted to the first year. Exclusions included patient's death or loss to follow-up within 12 months and subjects enrolled 80th or higher at a site. Departures were assessed for variance with higher patient rank, more frequent recruitment and later start date.

METHODS AND RESULTS

12,367 patients at 931 sites were analysed. Departures were more common for patients enrolled earlier at a site (p<0.0001). For example, compared with the 30th patient, the first had 47% more departures. Departures were also more common with slower enrollment and site start closer to the trial start date (p<0.0001). Similar patterns existed for queries.

CONCLUSIONS

Research performance improved during the VALsartan In Acute myocardial iNfarcTion consistent with a "learning curve". Although effects were not related to a change in outcome (mortality), learning curves in clinical research may have important safety, ethical, research quality and economic implications for trial conduct.

Association of the 98T ELAM-1 polymorphism with increased bleeding after cardiac surgery

OBJECTIVE

Hemorrhage continues to be a major problem after cardiac surgery despite the routine use of antifibrinolytic drugs, with striking inter-patient variability poorly explained by already known risk factors. The authors tested the hypothesis that genetic polymorphisms of inflammatory mediators and cellular adhesion molecules are associated with bleeding after cardiac surgery.

DESIGN

Prospective, observational study.

SETTING

Single, tertiary referral university heart center.

PARTICIPANTS

Adult patients undergoing aortocoronary surgery with cardiopulmonary bypass.

INTERVENTIONS

Patients (n = 759) had 10 mL of blood drawn preoperatively and genomic DNA isolated then genotyped for 17 polymorphisms in 7 candidate genes: tumor necrosis factor, interleukins 1beta and 6, interleukin 1 receptor antagonist, intercellular adhesion molecule-1 (ICAM-1), P-selectin and endothelial leucocyte adhesion molecule-1 (E-selectin). Multivariate analyses were used to relate clinical and genetic factors to bleeding and transfusion.

MEASUREMENTS AND MAIN RESULTS

The 98G/T polymorphism of the E-selectin gene was independently associated with bleeding after cardiac surgery (p = 0.002), after adjusting for significant clinical predictors (patient size and baseline hemoglobin concentration). There was a gene dose effect according to the number of minor alleles in the genotype; carriers of the minor allele bled 17% (GT) and 54% (TT) more than wild type (GG) genotypes, respectively (p = 0.01). Carriers of the minor allele also had longer activated partial thromboplastin times (p = 0.0023) and increased fresh frozen plasma transfusion (p = 0.03) compared with wild type.

CONCLUSIONS

The authors found a dose-related association between the 98T E-selectin polymorphism and bleeding after cardiac surgery, independent of and additive to standard clinical risk factors.