Inflammation, oxidative stress and postoperative atrial fibrillation in cardiac surgery

Effects of febuxostat on atrial remodeling in a rabbit model of atrial fibrillation induced by rapid atrial pacing

Background

Febuxostat, a novel nonpurine selective inhibitor of xanthine oxidase (XO), may be used in the prevention and management of atrial fibrillation (AF). The purpose of this study was to evaluate the effects of febuxostat on atrial remodeling in a rabbit model of AF induced by rapid atrial pacing (RAP) and the mechanisms by which it acts.

Methods

Twenty-four rabbits were randomly divided into four groups: sham-operated group (Group S), RAP group (Group P), RAP with 5 mg/kg per day febuxostat group (Group LFP), and RAP with 10 mg/kg per day febuxostat group (Group HFP). All rabbits except those in Group S were subjected to RAP at 600 beats/min for four weeks. The effects of febuxostat on atrial electrical and structural remodeling, markers of inflammation and oxidative stress, and signaling pathways involved in the left atrium were examined.

Results

Shortened atrial effective refractory period (AERP), increased AF inducibility, decreased mRNA levels of Cav1.2 and Kv4.3, and left atrial enlargement and dysfunction were observed in Group P, and these changes were suppressed in the groups treated with febuxostat. Prominent atrial fibrosis was observed in Group P, as were increased levels of TGF-β1, Collagen I, and α-SMA and decreased levels of Smad7 and eNOS. Treatment with febuxostat attenuated these differences. Changes in inflammatory and oxidative stress markers induced by RAP were consistent with the protective effects of febuxostat.

Conclusions

This study is the first to find that febuxostat can inhibit atrial electrical and structural remodeling of AF by suppressing XO and inhibiting the TGF-β1/Smad signaling pathway.

Remote ischaemic preconditioning ameliorates sinus rhythm restoration rate through Cox maze radiofrequency procedure associated with inflammation reaction reduction

Remote ischaemic preconditioning (RIPC) as adjuvant to selective heart surgery attenuates cardiac injury and atrial fibrillation (AF) occurrence. We investigated its effect on sinus rhythm (SR) restoration rate in permanent AF patients undergoing Cox maze (CM) radiofrequency ablation with concomitant mitral valve surgery. From May 2013 to May 2017, 206 patients with rheumatic valve disease concomitant with permanent AF were randomized to receive prosthesis valve replacement and CM radiofrequency ablation procedure with (n = 104) or without (n = 102) RIPC (intermittent arm ischaemia through three cycles of 5-min inflation, followed by 5-min deflation of a blood pressure cuff). The primary end point of the study was freedom from cumulative AF without using antiarrhythmic drugs 1 year after operation; the secondary end points included inflammation reaction index over 48 h postoperatively and clinical outcomes. Baseline characteristics and preoperative data did not differ between groups. The SR restoration rates were significantly higher in the RIPC group, 85.6%, 83.7%, and 82.7%, than those in the control group, 72.5%, 70.6%, and 69.6%, at discharge, 6 months and 12 months, respectively, after the radiofrequency ablation procedure (P < 0.05). The serum concentration of high sensitivity C-reactive protein and neutrophil-lymphocyte ratio were significantly decreased at 12 h, 24 h, and 48 h postoperatively in the RIPC group compared to those in the control group (P < 0.05). RIPC induced by brief ischaemia and reperfusion of the arm ameliorated SR restoration rate in patients with permanent AF through CM radiofrequency ablation procedure and was associated with reduction of postoperative systemic inflammation reaction index.

Urinary Biomarkers of Oxidative Stress in Atrial Fibrillation

There is increasing evidence from molecular studies to support the role of inflammation and increased oxidative stress that produce structural and electrical atrial remodeling to produce Atrial Fbrillation (AF). Oxidative damage to cardiomyocytes yields chemical substances that are secreted in urine. These substances can serve as biomarkers that can be measured, potentially allowing clinicians to quantify oxidative damage to the heart.

Oxidative Stress and Neonatal Respiratory Extracorporeal Membrane Oxygenation

Oxidative stress is a frequent condition in critically ill patients, especially if exposed to extracorporeal circulation, and it is associated with worse outcomes and increased mortality. The inflammation triggered by the contact of blood with a non-endogenous surface, the use of high volumes of packed red blood cells and platelets transfusion, the risk of hyperoxia and the impairment of antioxidation systems contribute to the increase of reactive oxygen species and the imbalance of the redox system. This is responsible for the increased production of superoxide anion, hydrogen peroxide, hydroxyl radicals, and peroxynitrite resulting in increased lipid peroxidation, protein oxidation, and DNA damage. The understanding of the pathophysiologic mechanisms leading to redox imbalance would pave the way for the future development of preventive approaches. This review provides an overview of the clinical impact of the oxidative stress during neonatal extracorporeal support and concludes with a brief perspective on the current antioxidant strategies, with the aim to focus on the potential oxidative stress-mediated cell damage that has been implicated in both short and long-term outcomes.

Therapeutic Approaches Targeting Inflammation in Cardiovascular Disorders

Cardiovascular disease is a leading cause of morbidity and mortality in the Western world and represents an enormous global health burden. Significant advances have been made in the conservative, medical and surgical management across the range of cardiovascular diseases however the inflammatory components of these diseases have traditionally been neglected. Inflammation is certainly a key component of atherosclerosis, a chronic inflammatory condition, but it is at least correlative and predictive of risk in many other aspects of cardiovascular medicine ranging from heart failure to outcomes following reperfusion strategies. Inflammation therefore represents significant potential for future risk stratification of patients as well as offering new therapeutic targets across cardiovascular medicine. This review explores the role of inflammation in several of the major aspects of cardiovascular medicine focusing on current and possible future examples of the targeting of inflammation in prognosis and therapy. It concludes that future directions of cardiovascular research and clinical practice should seek to identify cohorts of patients with a significant inflammatory component to their cardiovascular condition or reaction to cardiovascular intervention. These patients might benefit from therapeutic strategies mounted against the inflammatory components implicated in their condition.

Up regulated Tmbim1 activation promotes high fat diet (HFD)-induced cardiomyopathy by enhancement of inflammation and oxidative stress

The prevalence of cardiomyopathy due to metabolic stress has up-regulated dramatically; nevertheless, its molecular mechanisms remain unclear. Here we suggested that transmembrane BAX inhibitor motif-containing 1 (Tmbim1) is down-regulated in the hearts of mice fed with high fat diet (HFD). We provided evidence that Tmbim1 knockout (KO) accelerated HFD-induced metabolic disorders in mice, as supported by the remarkable increase of fasting serum glucose and insulin levels. HFD-induced cardiac dysfunctions were greatly intensified by the loss of Tmbim1, along with higher levels of lactate dehydrogenase (LDH) and creatine kinase (CK) in serum. In addition, Tmbim1 deletion significantly enhanced lipid accumulation in heart of mice administrated with HFD. Furthermore, Tmbim1 knockout reinforced myocardial inflammation, evidenced by increasing the expression of pro-inflammatory cytokines (interleukin 1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α)), and the activation of nuclear factor-κB (NF-κB) signaling pathway. Tmbim1 deficiency strengthened oxidative damage in hearts of HFD-fed mice, accompanied with a significant reduction of nuclear factor-erythroid 2 related factor 2 (Nrf-2) pathway. In palmitate (PA)-treated primary cardiomyocytes, Tmbim1 ablation markedly enhanced cell inflammation and oxidative stress, which were abolished by the suppression of ROS generation and NF-κB activation. Taken together, these findings suggested that Tmbim1 might be a key suppressor of metabolic stress-induced cardiomyopathy, which could be a promising target for the treatment of metabolic syndrome-triggered myocardial damage and heart failure.

Role of inflammatory signaling in atrial fibrillation

Atrial fibrillation (AF), the most prevalent arrhythmia, is often associated with enhanced inflammatory response. Emerging evidence points to a causal role of inflammatory signaling pathways in the evolution of atrial electrical, calcium handling and structural remodeling, which create the substrate of AF development. In this review, we discuss the clinical evidence supporting the association between inflammatory indices and AF development, the molecular and cellular mechanisms of AF, which appear to involve multiple canonical inflammatory pathways, and the potential of anti-inflammatory therapeutic approaches in AF prevention/treatment.

Oxidative stress and atrial fibrillation: an update

Atrial remodelling involves electrophysiological and structural abnormalities that promote the development and perpetuation of atrial fibrillation. Experimental and clinical data indicate that oxidative stress is implicated in the pathophysiology of atrial remodelling. The mechanistic links between atrial remodelling and oxidative stress are complex with several underlying diseases and conditions may affect these pathways. Therefore, the development of antioxidant interventions in this setting remains difficult. Besides classical antioxidant compounds, several agents with pleiotropic effects, including anti-inflammatory and antioxidant, have been tested in experimental and clinical settings with variable results. Strategies applying conventional antioxidants in specific situations such as postoperative atrial fibrillation show beneficial effects, especially the two-step regimen of antioxidants combination. Of note, there are limited data on the development of strategies that target specific sources of reactive oxygen species implicated in atrial remodelling. Lifestyle, diet, and risk factors modification is a complementary promising approach. This updated review provides a concise and critical overview of all available data regarding oxidative stress and its modulation in atrial fibrillation. Future directions on this exciting field are also discussed.

Comparative Effects of Blood and Crystalloid Cardioplegia on Cellular Injury and Oxidative Stress in Cardiovascular Surgery

Purpose: The purpose of this study was to evaluate the effect of different cardioplegic solutions on endothelial integrity and oxidative stress in cardiovascular surgery.

Methods: In this randomized prospective study, after ethics approval and informed consent, 60 surgical patients were included. Patients undergoing coronary bypass surgery were randomized into two groups as warm blood cardioplegia (n = 30) and cold crystalloid cardioplegia (n = 30) following the cross-clamping. Measurements were performed at three time points: before induction of anesthesia (T1), at admission to intensive care unit (ICU) (T2) and at the 24th postoperative hour (T3). Besides biochemical routine hemodynamic monitoring, patients were assessed for the sialic acid (SA), ischemic-modified albumin (IMA), advanced oxide protein products (AOPPs), total thiol (SH), and free hemoglobin (fHb) level.

Results: Neither crystalloid nor blood cardioplegia led to significant changes in the AOPPs, T-SH, and SA level (p >0.05). Crystalloid cardioplegia, however, increased IMA level compared to both baseline (p <0.01) and blood cardioplegia group (p <0.05). fHb levels were transiently increased in both groups at the second-time point (p <0.001). fHb level was lower in the crystalloid group compared to that in the other group (p <0.05) at T2.

Conclusion: Cardioplegia type creates similar effects on glycocalyx integrity. However, myocardial protection could be provided with warm blood cardioplegia.

Postoperative atrial fibrillation following cardiac surgery: a persistent complication

Postoperative atrial fibrillation (POAF) is a common, expensive and potentially morbid complication following cardiac surgery. POAF occurs in around 35% of cardiac surgery cases and has a peak incidence on postoperative day 2. Patients who develop POAF incur on average $10 000-$20 000 in additional hospital treatment costs, 12-24 h of prolonged ICU time, and an additional 2 to 5 days in the hospital. POAF has been identified as an independent predictor of numerous adverse outcomes, including a 2- to 4-fold increased risk of stroke, reoperation for bleeding, infection, renal or respiratory failure, cardiac arrest, cerebral complications, need for permanent pacemaker placement, and a 2-fold increase in all-cause 30-day and 6-month mortality. The pathogenesis of POAF is incompletely understood but likely involves interplay between pre-existing physiological components and local and systemic inflammation. POAF is associated with numerous risk factors including advanced age, pre-existing conditions that cause cardiac remodelling and certain non-cardiovascular conditions. Clinical management of POAF includes both prophylactic and therapeutic measures, although the efficacy of many interventions remains in question. This review provides a comprehensive and up-to-date summary of the pathogenesis of POAF, outlines current clinical guidelines for POAF prophylaxis and management, and discusses new avenues for further investigation.

Wider perioperative glycemic fluctuations increase risk of postoperative atrial fibrillation and ICU length of stay

INTRODUCTION

Postoperative atrial fibrillation (POAF) is a common complication following cardiac surgery associated with increased morbidity and mortality. Although sustained hyperglycemia is a known risk factor of AF and poor ICU outcomes, emerging in-vitro studies reveal acute glycemic fluctuations to be an additional independent predictor of AF. The effect of acute glycemic fluctuations on the incidence of POAF in the clinical setting remains unclear. We aim to investigate the effect of the magnitude of acute perioperative glycemic fluctuations on the incidence of POAF in a multi-ethnic Southeast-Asian population.

METHODS

We obtained data from1743 patients who underwent elective CABG in a tertiary heart centre from 2009-2011. Patients were kept to a tight baseline glycemic control in accordance with hospital protocol. The magnitude of the difference between the highest and lowest perioperative glucose levels up till the first 48 postoperative hours was employed as a measure of glycemic fluctuation. Patients were divided into 4 groups for analysis based on the magnitude of glycemic fluctuation:A)0-2mmol/L(N = 147); B)>2-4mmol/L(N = 426); C)>4-6mmol/L(N = 513); D)>6mmol/L(N = 657).Our primary outcome was the incidence of POAF. Secondary outcomes included ICU and 30-day mortality and length of stay.

RESULTS

The overall incidence of POAF was 14.7%. This increased as the magnitude of glycemic fluctuation increased, and was statistically highest in Group D(16.4%) as compared with the other 3 sub-groups. Multivariate logistic regression revealed the magnitude of perioperative glycemic fluctuation to be an independent risk factor of POAF(O.R.1.06, 95% C.I.1.01-1.11, p = 0.014).ICU length of stay was statistically highest in Group D(63.1 hours, p = < .001). However, ICU and 30 day mortality rates were similar among the 4 groups.

CONCLUSION

Increased magnitudes of acute perioperative glycemic fluctuations are associated with a significantly increased risk of POAF and length of ICU stay; and should therefore be minimised but balanced against the risks of hypoglycemia so as to avoid POAF and optimise patient outcomes.

Impact of Different Serum Potassium Levels on Postresuscitation Heart Function and Hemodynamics in Patients with Nontraumatic Out-of-Hospital Cardiac Arrest

Background

Sustained return of spontaneous circulation (ROSC) can be initially established in patients with out-of-hospital cardiac arrest (OHCA); however, the early postresuscitation hemodynamics can still be impaired by high levels of serum potassium (hyperkalemia). The impact of different potassium levels on early postresuscitation heart function has remained unclear. We aim to analyze the relationship between different levels of serum potassium and postresuscitation heart function during the early postresuscitation period (the first hour after achieving sustained ROSC).

Methods

Information on 479 nontraumatic OHCA patients with sustained ROSC was retrospectively obtained. Measures of early postresuscitation heart function (rate, blood pressure, and rhythm), hemodynamics (urine output and blood pH), and the duration of survival were analyzed in the case of different serum potassium levels (low: <3.5; normal: 3.5–5; high: >5 mmol/L).

Results

Most patients (59.9%, n = 287) had previously presented with high levels of potassium. Bradycardia, nonsinus rhythm, urine output <1 ml/kg/hr, and acidosis (pH < 7.35) were more common in patients with high levels of potassium (all p < 0.05). Compared with hyperkalemia, a normal potassium level was more likely to be associated with a normal heart rate (OR: 2.97, 95% CI: 1.74–5.08) and sinus rhythm (OR: 2.28, 95% CI: 1.45–3.58). A low level of potassium was more likely to be associated with tachycardia (OR: 3.54, 95% CI: 1.32–9.51), urine output >1 ml/kg/hr (OR: 5.35, 95% CI: 2.58–11.10), and nonacidosis (blood pH >7.35, OR: 7.74, 95% CI: 3.78–15.58). The duration of survival was shorter in patients with hyperkalemia than that in patients whose potassium levels were low or normal (p < 0.05).

Conclusion

Early postresuscitation heart function and hemodynamics were associated with the serum potassium level. A high potassium level was more likely to be associated with bradycardia, nonsinus rhythm, urine output <1 ml/kg/hr, and acidosis. More importantly, a high potassium level decreased the duration of survival.

Association between incidence of atrial fibrillation and duration of cardiopulmonary bypass in coronary artery bypass graft surgery (CABG): a cohort study

BACKGROUND

Open heart surgery is one of the most common and valuable treatment methods for cardiovascular diseases, a common side effect of which is atrial fibrillation that occurs due to various reasons.

OBJECTIVE

To determine the relationship between incidence of atrial fibrillation (AF) and duration of cardiopulmonary bypass (CPB) in patients after open heart surgery.

METHODS

The present retrospective cohort study was conducted on 330 patients in Farshchian Heart Center through census. The required data were collected from medical records of the patients undergoing coronary bypass surgery using data collection between April 2015 and March 2015. Then, data analysis was performed using SPSS software (ver.16) at error level of p<0.05. The tests used in this study included independent-samples t-test, Mann-Whitney, and chi-squared tests.

RESULTS

Based on the results, mean age of the patients was 61.76±9.2, the majority of the patients (70.1%) were male. The association between Incidence of Atrial Fibrillation and cardiopulmonary pump time (minute) was not meaningful. Incidence of atrial fibrillation had statistically significant relationship with variables of mean age, BMI, PAC, PVC, creatinine and duration of hospitalization (p<0.05); on the other hand, variables of gender, cross clamp time (minute), intubation time (hour), and clinical history had no effect on atrial fibrillation incidence rate (p>0.05).

CONCLUSION

Since the pathogenesis of AF after cardiac surgery is believed to be multifactorial, including clinical variables and technical intraoperative factors, the relation between incidence of AF with mean age, BMI, PAC, PVC, creatinine and duration of hospitalization was significant. But AF was not related to cardiopulmonary pump time (minute). It is necessary to conduct further research on factors affecting incidence of atrial fibrillation.

Can dexmedetomidine reduce atrial fibrillation after cardiac surgery? A systematic review and meta-analysis

PURPOSE

Cardiac surgery patients always present with atrial fibrillation (AF) after admission to the intensive care unit, leading to high mortality and lengthy hospitalization. Dexmedetomidine (DEX) is a popular medication used for sedation in the intensive care unit; however, whether it can reduce AF needs to be analyzed.

MATERIALS AND METHODS

Three primary databases, Medline, Embase (Ovid SP) and the Cochrane Central Register of Controlled Trials (CENTRAL), were searched. All English language and randomized control designed clinical publications comparing DEX to control medicines for sedation after elective cardiac surgery were included. Two independent colleagues conducted the data extraction and quality assessments. The subgroup analysis was performed according to the medicine used, age, AF history, and whether previous beta-blocker premedication and cardiopulmonary bypass (CPB) were applied. The overall incidence of AF was analyzed.

RESULTS

A total of 1,295 patients in nine studies met the selection criteria among 2,587 studies screened from the database. After quantitative synthesis, our results revealed that the DEX group was not associated with a decreased incidence of AF compared with the placebo (risk ratio [RR] 0.76, 95% CI 0.37, 1.55, P=0.44) and morphine groups (RR 0.86, 95% CI 0.56, 1.31, P=0.48). Subgroup analysis also indicated that the DEX vs propofol comparison exhibited no difference: 1) for patients of age >60 years (P=0.69) or ≤60 years (P=0.69); 2) under CPB surgery (P=0.45) or without CPB surgery (P=0.88); 3) with beta-blocker premedication (P=0.32) or without beta-blocker premedication (P=0.90); and 4) with AF history (RR 1.07, 95% CI 0.85, 1.36, P=0.57) or without AF history (P=0.30).

CONCLUSION

This meta-analysis revealed that DEX could not reduce the incidence of AF compared to control medicines following cardiac surgery. DEX may have an increased influence on AF occurrence if patients had a history of AF. However, cautious interpretation should be made due to high clinical heterogeneity.

New-onset atrial fibrillation: an update

New-onset atrial fibrillation (NOAF) is the most common perioperative complication of heart surgery, typically occurring in the perioperative period. NOAF commonly occurs in patients who are elderly, or have left atrial enlargement, or left ventricular hypertrophy. Various factors have been identified as being involved in the development of NOAF, and numerous approaches have been proposed for its prevention and treatment. Risk factors include diabetes, obesity, and metabolic syndrome. For prevention of NOAF, β-blockers and amiodarone are particularly effective and are recommended by guidelines. NOAF can be treated by rhythm/rate control, and antithrombotic therapy. Treatment is required in patients with decreased cardiac function, a heart rate exceeding 130 beats/min, or persistent NOAF lasting for ≥ 48 h. It is anticipated that anticoagulant therapies, as well as hemodynamic management, will also play a major role in the management of NOAF. When using warfarin as an anticoagulant, its dose should be adjusted based on PT-INR. PT-INR should be controlled between 2.0 and 3.0 in patients aged < 70 years and between 1.6 and 2.6 in those aged ≥ 70 years. Rate control combined with antithrombotic therapies for NOAF is expected to contribute to further advances in treatment and improvement of survival.

Influence of Inflammation and Atherosclerosis in Atrial Fibrillation

BACKGROUND

Inflammation markers have been associated with cardiovascular diseases including atrial fibrillation. This arrhythmia is the most frequent, with an incidence of 38/1000 person-years.

PURPOSE OF REVIEW

The aims of this study are to discuss the association between inflammation, atherosclerosis and atrial fibrillation and its clinical implications. Atherosclerosis is a chronic inflammatory disease and inflammation is a triggering factor of atherosclerotic plaque rupture. In addition to coronary artery disease, clinical conditions identified as risk factors for atrial fibrillation (AF) are also associated with the inflammatory state such as obesity, diabetes mellitus, hypertension, heart failure, metabolic syndrome and sedentary lifestyle. Biomarkers of inflammation, oxidative stress, coagulation, and myocardial necrosis have been identified in patients with atrial fibrillation and these traditional risk factors. Some markers of inflammation were identified as predictors of recurrence of this arrhythmia, subsequent myocardial infarction, stroke by embolism, and death. Thus, approaches to manipulate the inflammatory pathways may be therapeutic interventions, benefiting patients with AF and increased inflammatory markers.

Does dexmedetomidine have an antiarrhythmic effect on cardiac patients? A meta-analysis of randomized controlled trials

Background

Cardiac surgery patients often experience several types of tachyarrhythmias after admission to the intensive care unit (ICU), which increases mortality and morbidity. Dexmedetomidine (DEX) is a popular medicine used for sedation in the ICU, and its other pharmacological characteristics are gradually being uncovered.

Purpose

To determine whether DEX has an antiarrhythmic effect after cardiac surgery.

Methods

The three primary databases MEDLINE, Embase (OVID SP) and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched, and all English-language and randomized control-designed clinical publications comparing DEX to control medicines for sedation after elective cardiac surgery were included. Two colleagues independently extracted the data and performed other quality assessments. A subgroup analysis was performed according to the different medicines used and whether cardiopulmonary bypass (CPB) was applied. All tachyarrhythmias that occurred in the atria and ventricles were analyzed.

Results

A total of 1295 patients in 9 studies met the selection criteria among 2587 studies that were screened. After quantitative synthesis, our results revealed that the DEX group was associated with a lower incidence of ventricular arrhythmia (VA, OR 0.24, 95% CI 0.09–0.64, I² = 0%, P = 0.005) than the control group. Subgroup analysis did not reveal a significant difference between the DEX and propofol subgroups (OR 0.13, 95% CI 0.03–0.56, I² = 0%, P = 0.007). Additionally, no difference in the incidence of atrial fibrillation (AF) was observed regardless of the different control medicines (OR 0.82, 95% CI 0.60–1.10, I² = 25%, P = 0.19) or whether CPB was applied.

Conclusions

This meta-analysis revealed that DEX has an antiarrhythmic effect that decreases the incidence of VA compared to other drugs used for sedation following cardiac surgery. DEX may not have an effect on AF, but cautious interpretation should be exercised due to high heterogeneity.

Atrial Fibrillation Initiated by Early Afterdepolarization-Mediated Triggered Activity during Acute Oxidative Stress: Efficacy of Late Sodium Current Blockade

Background

The mechanism of Atrial Fibrillation (AF) that emerges spontaneously during acute oxidative stress is poorly defined and its drug therapy remains suboptimal. We hypothesized that oxidative activation of Ca-calmodulin dependent protein kinase (CaMKII) promotes Early Afterdepolarization-(EAD)-mediated triggered AF in aged fibrotic atria that is sensitive to late Na current (I_Na-L) blockade.

Method and Results

High-resolution voltage optical mapping of the Left and Right Atrial (LA & RA) epicardial surfaces along with microelectrode recordings were performed in isolated-perfused male Fisher 344 rat hearts in Langendorff setting. Aged atria (23-24 months) manifested 10-fold increase in atrial tissue fibrosis compared to young/adult (2-4 months) atria (P<0001. Spontaneous AF arose in 39 out of 41 of the aged atria but in 0 out of 12 young/adult hearts (P<001) during arterial perfusion of with 0.1 mm of hydrogen peroxide (H₂O₂). Optical Action Potential (AP) activation maps showed that the AF was initiated by a focal mechanism in the LA suggestive of EAD-mediated triggered activity. Cellular AP recordings with glass microelectrodes from the LA epicardial sites showing focal activity confirmed optical AP recordings that the spontaneous AF was initiated by late phase 3 EAD-mediated triggered activity. Inhibition of CaMKII activity with KN-93 (1 μM) (N=6) or its downstream target, the enhanced I_Na-L with GS-967 (1 μM), a specific blocker of I_Na-L (N=6), potently suppressed the AF and prevented its initiation when perfused 15 min prior to H₂O₂ (n=6).

Conclusions

Increased atrial tissue fibrosis combined with acute oxidative activation of CaMK II Initiate AF by EAD-mediated triggered activity. Specific block of the I_Na-L with GS-967 effectively suppresses the AF. Drug therapy of oxidative AF in humans with traditional antiarrhythmic drugs remains suboptimal; suppressing I_Na-L offers a potential new strategy for effective suppression of oxidative human AF that remains suboptimal.

Omega-3 Index and Anti-Arrhythmic Potential of Omega-3 PUFAs

Omega-3 polyunsaturated fatty acids (PUFAs), namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are permanent subjects of interest in relation to the protection of cardiovascular health and the prevention of the incidence of both ventricular and atrial arrhythmias. The purpose of this updated review is to focus on the novel cellular and molecular effects of omega-3 PUFAs, in the context of the mechanisms and factors involved in the development of cardiac arrhythmias; to provide results of the most recent studies on the omega-3 PUFA anti-arrhythmic efficacy and to discuss the lack of the benefit in relation to omega-3 PUFA status. The evidence is in the favor of omega-3 PUFA acute and long-term treatment, perhaps with mitochondria-targeted antioxidants. However, for a more objective evaluation of the anti-arrhythmic potential of omega-3 PUFAs in clinical trials, it is necessary to monitor the basal pre-interventional omega-3 status of individuals, i.e., red blood cell content, omega-3 index and free plasma levels. In the view of evidence-based medicine, it seems to be crucial to aim to establish new approaches in the prevention of cardiac arrhythmias and associated morbidity and mortality that comes with these conditions.

Oxidative stress and inflammation as central mediators of atrial fibrillation in obesity and diabetes

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in humans. Several risk factors promote AF, among which diabetes mellitus has emerged as one of the most important. The growing recognition that obesity, diabetes and AF are closely intertwined disorders has spurred major interest in uncovering their mechanistic links. In this article we provide an update on the growing evidence linking oxidative stress and inflammation to adverse atrial structural and electrical remodeling that leads to the onset and maintenance of AF in the diabetic heart. We then discuss several therapeutic strategies to improve atrial excitability by targeting pathways that control oxidative stress and inflammation.

Linking atrial fibrillation with non-alcoholic fatty liver disease: potential common therapeutic targets

Non-alcoholic fatty liver disease (NAFLD) and atrial fibrillation (AF) are common chronic non-infectious diseases with rising incidences. NAFLD is an independent risk factor for the onset of AF, after adjusting potentially related factors. The pathogenesis of these diseases share several mechanisms including reduced adiponectin level, insulin resistance, and renin angiotensin aldosterone system (RAAS) activation, in addition to activation of common disease pathways that promote inflammation, oxidative stress, and fibrosis. Furthermore, statins and RAAS blockers exert therapeutic effects concurrently on NAFLD and AF. The common pathogenesis of NAFLD and AF may serve as a potential therapeutic target in the future.

Plasma Catecholamine Levels on the Morning of Surgery Predict Post-Operative Atrial Fibrillation

OBJECTIVES

This study sought to determine whether plasma catecholamines and monoamine oxidase-B (MOA-B) are associated with post-operative atrial fibrillation (POAF) in patients undergoing elective cardiac surgery.

BACKGROUND

Although intra- and post-operative adrenergic tone has been demonstrated to be an causative factor for POAF, the role and association of pre-operative plasma catecholamines remains unclear.

METHODS

Prior to administration of anesthesia on the morning of surgery, blood samples were obtained from 324 patients undergoing nonemergent coronary artery bypass graft and/or aortic valve surgery with cardiopulmonary bypass at East Carolina Heart Institute. The concentrations of norepinephrine (NE), dopamine (DA), epinephrine (EPI), and enzyme MAO-B were assessed in platelet-rich plasma. A log-binomial regression model was used to determine the association between quartiles of these variables and POAF.

RESULTS

Levels of NE (p = 0.0006) and EPI (p = 0.047) in the 4th quartile [Formula: see text] were positively associated with POAF, whereas DA (p = 0.0034) levels in the 4th quartile [Formula: see text] were inversely associated with POAF. Adjusting for age, heart failure (HF), and history of atrial fibrillation, the composite pre-operative (adrenergic) plasma marker [Formula: see text] was associated with a 4-fold increased occurrence of POAF (adjusted p = 0.0001). No association between plasma MAO-B and POAF was observed.

CONCLUSIONS

Our results suggest that pre-operative adrenergic tone is an important factor underlying POAF. This information provides evidence that assessment of plasma catecholamines may be a low-cost method that is easy to implement for predicting which patients are likely to develop POAF. More investigation in a multicentric setting is needed to validate our results.

Fish oil supplementation for primary prevention of atrial fibrillation after coronary artery bypass graft surgery: A randomized clinical trial

BACKGROUND

Atrial fibrillation (AF) after cardiac surgery is a common complication that may influence patients' early and long term outcomes and hospital costs. The purpose of this study was to assess the effect of fish oil on occurrence of AF following coronary artery bypass graft surgery (CABG).

METHODS

This study was a single-center, randomized, double blinded, placebo-controlled clinical trial. Four-hundred and one patients undergoing coronary artery bypass graft surgery were randomly assigned to receive 2 g/d fish oil or placebo (olive oil) for at least 5 days before surgery. The primary end point was defined as time to AF improvement After AF incidence following isolated CABG or a need for pharmacologic therapy or cardioversion.

RESULTS

The time to AF improvement in intervention group was shorter than control group (HR: 2.05; 95% CI = 0.70-6.22, P = 0.20). The incidence of AF in the intervention and control groups was 8.40% vs. 14.07% respectively (p = 0.07). Mean total duration of AF was 20.96 ± 4.71 h in intervention groups and 46.87 ± 7.44 h in control groups (p = 0.04). Mean duration of stay in the ICU and total hospital stay showed a significant reduction in the intervention group (p = 0.003 and p = 0.04, respectively).

CONCLUSION

The consumption of PUFA leads to a shorter time to AF improvement, which was not statistically significant. The incidence of AF in patients undergoing CABG surgery was decreased by approximately 5.7%; which was statistically on the borderline. Fish oil reduced median length of stay in the ICU and hospital. Further well-designed studies are needed to overcome the limitations of the existing trials and provide conclusive conclusions.

Coronary Artery Bypass Graft Surgery and Dementia Risk in the Cardiovascular Health Study

INTRODUCTION

The association between history of coronary artery bypass graft surgery (CABG) and dementia risk remains unclear.

METHODS

We conducted a prospective cohort analysis using data on 3155 elderly adults free from prevalent dementia from the US population-based Cardiovascular Health Study (CHS) with adjudicated incident all-cause dementia, Alzheimer disease (AD), vascular dementia (VaD), and mixed dementia.

RESULTS

In the CHS, the hazard ratio (HR) for all-cause dementia was 1.93 [95% confidence interval (CI), 1.36-2.74] for those with CABG history compared with those with no CABG history after adjustment for potential confounders. Similar HRs were observed for AD (HR=1.71; 95% CI, 0.98-2.98), VaD (HR=1.42; 95% CI, 0.56-3.65), and mixed dementia (HR=2.73; 95% CI, 1.55-4.80). The same pattern of results was observed when these CHS findings were pooled with a prior prospective study, the pooled HRs were 1.96 (95% CI, 1.42-2.69) for all-cause dementia, 1.71 (95% CI, 1.04-2.79) for AD and 2.20 (95% CI, 0.78-6.19) for VaD.

DISCUSSION

Our results suggest CABG history is associated with long-term dementia risk. Further investigation is warranted to examine the causal mechanisms which may explain this relationship or whether the association reflects differences in coronary artery disease severity.

Storage time of intraoperative transfused allogeneic red blood cells is not associated with new-onset postoperative atrial fibrillation in cardiac surgery

BACKGROUND

Allogeneic red blood cell (RBC) transfusion has been associated with new-onset postoperative atrial fibrillation (POAF) following cardiac surgery. Prolonged storage time of RBC may increase the risk. The primary aim of the study was to evaluate whether the storage time of RBC is associated with development of POAF.

MATERIALS AND METHODS

Pre-, per- and postoperative data were retrieved from the Western Denmark Heart Registry and local blood banks regarding patients who underwent coronary artery bypass surgery, valve surgery or combined procedures in Aalborg or Aarhus University Hospital during 2010-2014. Multiple logistic regression was used to determine the risk of POAF according to transfusion of RBC on the day of surgery. Furthermore, we determined trend in storage time of RBC according to risk of POAF using restricted cubic splines. Patients with a history of preoperative atrial fibrillation, patients who received transfusions preoperative and patients who died at the day of surgery were among excluded patients.

RESULTS

A total of 2,978 patients with a mean age of 66.4 years were included and 609 patients (21%) received RBC transfusion on the day of surgery. POAF developed in 752 patients (25%) and transfused patients were at an increased risk compared with non-transfused patients (adjusted Odds Ratios for patients receiving RBC: 1.37; 95% CI: 1.11-1.69, P-value = 0.004). However, RBC transfusion was not necessarily the cause of POAF and may only be a marker for development of POAF. There was no significant association between storage time of RBC and POAF.

CONCLUSIONS

In contrast to intraoperative allogeneic RBC transfusion in general, increased storage time of RBC is not associated with development of POAF in cardiac surgery.

Preoperative Antihypertensive Medication in Relation to Postoperative Atrial Fibrillation in Patients Undergoing Cardiac Surgery: A Meta-Analysis

Background. We undertake a systematic review and meta-analysis to evaluate the effect of preoperative hypertension and preoperative antihypertensive medication to postoperative atrial fibrillation (POAF) in patients undergoing cardiac surgery. Methods. We searched PubMed, Embase, and Cochrane Library (from inception to March 2016) for eligible studies. The outcomes were the effects of preoperative hypertension, preoperative calcium antagonists regimen, preoperative ACE inhibitors regimen, and preoperative beta blocking agents regimen with POAF. We calculated pooled risk ratios (OR) and 95% CIs using random- or fixed-effects models. Results. Twenty-five trials involving 130087 patients were listed. Meta-analysis showed that the number of preoperative hypertension patients in POAF group was significantly higher (P < 0.05), while we found that there are no significant differences between two groups in Asia patients by subgroup analysis, which is in contrast to other outcomes. Compared with the Non-POAF group, the number of patients who used calcium antagonists and ACE inhibitors preoperatively in POAF group was significantly higher (P < 0.05). And we found that there were no significant differences between two groups of preoperative beta blocking agents used (P = 0.08). Conclusions. Preoperative hypertension and preoperative antihypertensive medication in patients undergoing cardiac operations seem to be associated with higher risk of POAF.

Relationship between Angiotensin Converting Enzyme, Apelin, and New-Onset Atrial Fibrillation after Off-Pump Coronary Artery Bypass Grafting

It has been shown that inflammation and oxidative stress are important factors in postoperative atrial fibrillation (POAF). Angiotensin converting enzyme (ACE) and apelin have a close relationship with inflammation and oxidative stress. The effect of ACE and apelin on POAF after off-pump coronary artery bypass grafting (OPCABG) remains a question. The concentrations of serum ACE, angiotensin II (Ang II), apelin, bradykinin (BK), malondialdehyde (MDA), and C reactive protein (CRP) were measured in the perioperative period of OPCABG. The levels of serum ACE in the POAF group were higher than in the no POAF group both preoperatively and postoperatively. Apelin in the POAF group was lower than in the no POAF group. There was a correlation between serum ACE and apelin. Postoperatively, CRP and MDA in the POAF group were higher than in the no POAF group; however, there was no difference before the operation. Preoperative ACE and apelin were both significant and independent risk factors for POAF. In conclusion, the high ACE and low apelin preoperatively led to CRP and MDA being increased postoperatively, which was probably associated with POAF after OPCABG. Apelin may be a new predictor for POAF.

The suppressive effects of landiolol administration on the occurrence of postoperative atrial fibrillation and tachycardia, and plasma IL-6 elevation in patients undergoing esophageal surgery: A randomized controlled clinical trial

STUDY OBJECTIVE

To determine whether perioperative landiolol administration suppresses postoperative atrial fibrillation (AF) and the plasma cytokines elevation in patients undergoing esophageal cancer surgery.

DESIGN

A prospective, randomized controlled trial.

SETTING

Akita University Hospital, Akita, Japan, from April 2012 to January 2015.

PATIENTS

Forty American Society of Anesthesiologists grade I-II patients undergoing elective esophagectomy.

INTERVENTIONS

Patients were randomly divided into two groups, landiolol group (landiolol: 5μg/kg/min) and control group (the same volume of covered saline). Landiolol or saline was infused continuously from the induction of anesthesia until next morning.

MEASUREMENTS

We examined the new onset of AF and sinus tachycardia, and measured plasma concentrations of cytokines (IL-1β, IL-6, IL-8, IL-10, and TNF-α) just before surgery, at the end of surgery, the next day, and 2days after surgery. Data (mean±SD) were analyzed using two-way ANOVA followed by the Bonferroni"s test for post hoc comparison; a P<0.05 was considered statistically significant.

MAIN RESULTS

Demographic data were similar between the landiolol and the control groups. The incidence of AF was significantly lower in the landiolol group (1/19=5.3%) compared with the control group (7/20=35%) as well as sinus tachycardia (landiolol group, 0/19=0% vs. control group, 5/20=25%). Plasma IL-6 level at the end of surgery was significantly lower in the landiolol group compared with the control group, but the other plasma cytokines levels were similar between the two groups during the entire study period.

CONCLUSIONS

Perioperative landiolol administration suppressed the incidence of new-onset of AF as well as sinus tachycardia, and the plasma IL-6 elevation in patients undergoing esophageal cancer surgery.

Manubrium-limited ministernotomy versus conventional sternotomy for aortic valve replacement (MAVRIC): study protocol for a randomised controlled trial

Background

Aortic valve replacement is one of the most common cardiac surgical procedures performed worldwide. Conventional aortic valve replacement surgery is performed via a median sternotomy; the sternum is divided completely from the sternal notch to the xiphisternum. Minimally invasive aortic valve replacement, using a new technique called manubrium-limited ministernotomy, divides only the manubrium from the sternal notch to 1 cm below the manubrio-sternal junction.

More than one third of patients undergoing conventional sternotomy develop clinically significant bleeding requiring post-operative red blood cell transfusion. Case series data suggest a potentially clinically significant difference in red blood cell transfusion requirements between the two techniques. Given the implications for National Health Service resources and patient outcomes, a definitive trial is needed.

Methods/design

This is a single-centre, single-blind, randomised controlled trial comparing aortic valve replacement surgery using manubrium-limited ministernotomy (intervention) and conventional median sternotomy (usual care). Two hundred and seventy patients will be randomised in a 1:1 ratio between the intervention and control arms, stratified by baseline logistic EuroSCORE and haemoglobin value. Patients will be followed for 12 weeks from discharge following their index operation. The primary outcome is the proportion of patients who receive a red blood cell transfusion post-operatively within 7 days of surgery. Secondary outcomes include red blood cell and blood product transfusions, blood loss, re-operation rates, sternal wound pain, quality of life, markers of inflammatory response, hospital discharge, health care utilisation, cost and cost effectiveness and adverse events.

Discussion

This is the first trial to examine aortic valve replacement via manubrium-limited ministernotomy versus conventional sternotomy when comparing red blood cell transfusion rates following surgery. Surgical trials present significant challenges; strengths of this trial include a rigorous research design, standardised surgery performed by experienced consultant cardiothoracic surgeons, an agreed anaesthetic regimen, patient blinding and consultant-led patient recruitment. The MAVRIC trial will demonstrate that complex surgical trials can be delivered to exemplary standards and provide the community with the knowledge required to inform future care for patients requiring aortic valve replacement surgery.

Trial registration

International Standard Randomised Controlled Trial Number (ISRCTN) ISRCTN29567910. Registered on 3 February 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1768-4) contains supplementary material, which is available to authorized users.

Detection of Myocardial Injury Using miRNAs Expression as Genetic Biomarkers in Acute Cardiac Care

Cardiovascular disease is a leading cause of death globally. At present, there are many ways to diagnose this pathophysiology. The greatest disadvantages related to current biomarkers are their low specificity, low selectivity and low accuracy. A new method, extensively studied recently, is the expression of miRNAs, used as genetic biomarkers for the early diagnosis of cardiovascular diseases. This paper presents an update of miRNAs species expression that can serve as early diagnostic biomarkers and for the continuous monitoring of patients with cardiovascular disease.

Autophagy: an adaptive physiological countermeasure to cellular senescence and ischaemia/reperfusion-associated cardiac arrhythmias

Oxidative stress placed on tissues that involved in pathogenesis of a disease activates compensatory metabolic changes, such as DNA damage repair that in turn causes intracellular accumulation of detritus and ‘proteotoxic stress’, leading to emergence of ‘senescent’ cellular phenotypes, which express high levels of inflammatory mediators, resulting in degradation of tissue function. Proteotoxic stress resulting from hyperactive inflammation following reperfusion of ischaemic tissue causes accumulation of proteinaceous debris in cells of the heart in ways that cause potentially fatal arrhythmias, in particular ventricular fibrillation (VF). An adaptive response to VF is occurrence of autophagy, an intracellular bulk degradation of damaged macromolecules and organelles that may restore cellular and tissue homoeostasis, improving chances for recovery. Nevertheless, depending on the type and intensity of stressors and inflammatory responses, autophagy may become pathological, resulting in excessive cell death. The present review examines the multilayered defences that cells have evolved to reduce proteotoxic stress by degradation of potentially toxic material beginning with endoplasmic reticulum‐associated degradation, and the unfolded protein response, which are mechanisms for removal from the endoplasmic reticulum of misfolded proteins, and then progressing through the stages of autophagy, including descriptions of autophagosomes and related vesicular structures which process material for degradation and autophagy‐associated proteins including Beclin‐1 and regulatory complexes. The physiological roles of each mode of proteotoxic defence will be examined along with consideration of how emerging understanding of autophagy, along with a newly discovered regulatory cell type called telocytes, may be used to augment existing strategies for the prevention and management of cardiovascular disease.

Association of admission serum laboratory parameters with new-onset atrial fibrillation after a primary percutaneous coronary intervention

OBJECTIVES

New-onset atrial fibrillation (NOAF) during hospitalization is considered a frequent complication associated with worse outcomes in the setting of ST-segment elevation myocardial infarction (STEMI). We aimed to investigate the association of admission serum laboratory parameters, neutrophil to lymphocyte ratio (NLR), and monocyte to high-density lipoprotein ratio (MHR) with NOAF in STEMI patients treated with a primary percutaneous coronary intervention (PCI).

PATIENTS AND METHODS

A total of 621 patients who were hospitalized with a diagnosis of STEMI and treated with primary PCI were retrospectively enrolled in the study. NOAF during index hospitalization and overall mortality were reported as the clinical outcomes.

RESULTS

In our study population, 40 (6.4%) patients developed NOAF during index hospitalization. Monocyte counts, mean platelet volume (MPV), red cell distribution width (RDW), NLR, MHR, C-reactive protein (CRP), creatinine, glucose, and uric acid levels were higher in the NOAF+ group compared with the NOAF- group. In multivariate regression analysis, age, left-ventricular ejection fraction, left atrial volumes, admission heart rate, multivessel disease, increased levels of CRP, MPV, RDW, uric acid, NLR, and MHR independently predicted NOAF. In addition, NOAF was found to be an independent predictor of overall mortality in the study population.

CONCLUSION

For the first time in the literature, admission serum levels of MPV, RDW, uric acid, NLR, and MHR were found to be correlated independently with NOAF after primary PCI.

Effect of colchicine in prevention of pericardial effusion and atrial fibrillation: a meta-analysis

Randomized, controlled trials (RCTs) have assessed the effect of colchicine therapy in prevention of pericardial effusion (PE) and atrial fibrillation (AF). However, the effects are still inconclusive. PubMed, Cochrane Library, Google Scholar, and EMBASE database were searched. Primary outcome was the risk of PE and AF. Ten RCTs with 1981 patients and a mean follow-up of 12.6 months were included. Colchicine therapy was not associated with a significantly lower risk of post-operative PE (RR, 0.89; 95 % CI 0.70-1.13; p = 0.33, I (2) = 72.8 %) and AF (RR, 0.77; 95 % CI 0.52-1.13; p = 0.18, I (2) = 47.3 %). However, rates of pericarditis recurrence, symptoms persistence, and pericarditis-related hospitalization were significantly decreased with colchicine treatment. In addition, cardiac tamponade occurrence was similar between groups, and adverse events were significantly higher in the colchicine group. Colchicine may not significantly decrease the post-operative risk of PE and AF. However, only limited studies about patients undergoing cardiac surgery provide data about PE and AF.

Low preoperative selenium is associated with post-operative atrial fibrillation in patients having intermediate-risk coronary artery surgery

BACKGROUND/OBJECTIVES

Post-operative atrial fibrillation (POAF) is a frequent complication of cardiac surgery. Oxidative stress and reduced antioxidant function have major roles in its development. Selenium is a key to normal antioxidant function, and levels are often low before cardiac surgery. This study investigated whether low preoperative selenium levels were associated with POAF in cardiac surgical patients.

SUBJECTS/METHODS

Using the Society of Thoracic Surgeons (STS) Mortality risk score, 50 patients having primary coronary artery bypass grafts (CABG) surgery were divided into two groups: (i) low-risk group (STS ⩽0.5%; n=26) and (ii) intermediate-risk group (STS ⩾2.0%; n=24). Plasma levels of selenium, glutathione peroxidase (GPx) and malondialdehyde (MDA) were measured in all patients at anaesthetic induction, after aortic cross-clamp removal, 3 h post cardiopulmonary bypass and on post-operative days 1 and 5. Multiple logistic regression was used to assess whether selenium levels were associated with POAF development.

RESULTS

Seventeen patients developed POAF (14 patients in the intermediate-risk group and 3 patients in the low-risk group). Preoperative selenium was lower in patients who developed POAF compared with those with normal sinus rhythm (0.73±0.16 vs 0.89±0.13 μmol/l, P=0.005), and this was independently associated with POAF (PR 0.32; 95% confidence credible interval (95%cI) 0.06-0.85, P=0.016). Regardless of POAF, preoperative selenium was lower in the intermediate-risk patients than in the low-risk patients (0.77±0.15 vs 0.89±0.14 μmol/l; P=0.004).

CONCLUSIONS

Intermediate-risk patients with low preoperative selenium levels may be at a greater risk of developing POAF following CABG. This raises the question of whether selenium supplementation in select cardiac surgical patients may reduce their POAF risk.

Ischemic Stroke after Heart Transplantation

Cerebrovascular complications after orthotopic heart transplantation (OHT) are more common in comparison with neurological sequelae subsequent to routine cardiac surgery. Ischemic stroke and transient ischemic attack (TIA) are more common (with an incidence of up to 13%) than intracranial hemorrhage (2.5%). Clinically, ischemic stroke is manifested by the appearance of focal neurologic deficits, although sometimes a stroke may be silent or manifests itself by the appearance of encephalopathy, reflecting a diffuse brain disorder. Ischemic stroke subtypes distribution in perioperative and postoperative period after OHT is very different from classical distribution, with different pathogenic mechanisms. Infact, ischemic stroke may be caused by less common and unusual mechanisms, linked to surgical procedures and to postoperative inflammation, peculiar to this group of patients. However, many strokes (40%) occur without a well-defined etiology (cryptogenic strokes). A silent atrial fibrillation (AF) may play a role in pathogenesis of these strokes and P wave dispersion may represent a predictor of AF. In OHT patients, P wave dispersion correlates with homocysteine plasma levels and hyperhomocysteinemia could play a role in the pathogenesis of these strokes with multiple mechanisms increasing the risk of AF. In conclusion, stroke after heart transplantation represents a complication with considerable impact not only on mortality but also on subsequent poor functional outcome.