Predictive Significance of Plasma Levels of Interleukin-6 and High-Sensitivity C-Reactive Protein in Atrial Fibrillation after Coronary Artery Bypass Surgery

Biomarkers of inflammation and coagulation after minimally invasive mitral valve surgery: a prospective comparison to conventional surgery

OBJECTIVES

Minimally invasive cardiac surgery techniques are increasingly used but have longer cardiopulmonary bypass time, which may increase inflammatory response and negatively affect coagulation. Our aim was to compare biomarkers of inflammation and coagulation as well as transfusion rates after minimally invasive mitral valve repair and mitral valve surgery using conventional sternotomy.

DESIGN

A prospective non-randomized study was performed enrolling 71 patients undergoing mitral valve surgery (35 right mini-thoracotomy and 36 conventional sternotomy procedures). Blood samples were collected pre- and postoperatively to assess inflammatory response. Thromboelastometry (ROTEM) was performed to assess coagulation, and transfusion rates were monitored.

RESULTS

The minimally invasive group had longer cardiopulmonary bypass times compared to the sternotomy group: 127 min ([115-146] vs 79 min [65-112], p < 0.001) and were cooled to a lower temperature during cardiopulmonary bypass, 34 °C vs 36 °C (p = 0.04). IL-6 was lower in the minimally invasive group compared to the conventional sternotomy group when measured at the end of the surgical procedure, (38 [23-69] vs 61[41-139], p = 0.008), but no differences were found at postoperative day 1 or postoperative day 3. The transfusion rate was lower in the minimally invasive group (14%) compared to full sternotomy (35%, p = 0.04) and the chest tube output was reduced, (395 ml [190-705] vs 570 ml [400-1040], p = 0.04).

CONCLUSIONS

Our data showed that despite the longer use of extra corporal circulation during surgery, minimally invasive mitral valve repair is associated with reduced inflammatory response, lower rates of transfusion, and reduced chest tube output.

Effects of multimodal low-opioid anesthesia protocol during on-pump coronary artery bypass grafting: a prospective cohort study

BACKGROUND

The most favorable anesthesia protocol during on-pump coronary artery bypass grafting (CABG) in patients with coronary heart disease remains unclear, despite previous publications regarding the interaction between anesthesia protocol and postoperative complications. The aim of the study was to compare the effect of a multimodal low-opioid anesthesia protocol (MLOP) on early postoperative complications during on-pump CABG.

METHODS

A single-center prospective cohort study including 120 patients undergoing on-pump CABG aged 18 to 65 years, divided into two groups according to undergoing MLOP or routine-opioid anesthesia protocol (ROP). The analyzed parameters were plasma IL-6 levels, complications, duration of mechanical ventilation, length of intensive care unit stay, and hospitalization.

RESULTS

In the MLOP group, the levels of IL-6 at the end of the surgery were 25.6% significantly lower compared to the ROP group (33.4 ± 9.4 vs. 44.9 ± 15.9, p < 0.0001), the duration of mechanical ventilation was significantly shorter (2.0 (2.0; 3.0) h vs. 4.0 (3.0; 5.0) h, p < 0.001), the incidence of low cardiac output syndrome was almost two and half times lower (7 (11.7%) vs. 16 (26.7%), p = 0.037), and also the incidence of postoperative atrial fibrillation was significantly lower (9 (15.0%) vs. 19 (31.7%), p = 0.031).

CONCLUSION

Our study confirms that using MLOP was characterized by significantly lower levels of IL-6 at the end of surgery and a lower incidence of low cardiac output syndrome and postoperative atrial fibrillation than ROP.

TRIAL REGISTRATION

The study is registered in clinicaltrials.gov №NCT05514652.

Patterns of cytokine release and association with new onset of post-cardiac surgery atrial fibrillation

Introduction

Postoperative Atrial Fibrillation (POAF) is a common complication of cardiac surgery, associated with increased mortality, stroke risk, cardiac failure and prolonged hospital stay. Our study aimed to assess the patterns of release of systemic cytokines in patients with and without POAF.

Methods

A post-hoc analysis of the Remote Ischemic Preconditioning (RIPC) trial, including 121 patients (93 males and 28 females, mean age of 68 years old) who underwent isolated coronary artery bypass grafting (CABG) and aortic valve replacement (AVR). Mixed-effect models were used to analyze patterns of release of cytokines in POAF and non-AF patients. A logistic regression model was used to assess the effect of peak cytokine concentration (6 h after the aortic cross-clamp release) alongside other clinical predictors on the development of POAF.

Results

We found no significant difference in the patterns of release of IL-6 (p = 0.52), IL-10 (p = 0.39), IL-8 (p = 0.20) and TNF-α (p = 0.55) between POAF and non-AF patients. Also, we found no significant predictive value in peak concentrations of IL-6 (p = 0.2), IL-8 (p = >0.9), IL-10 (p = >0.9) and Tumour Necrosis Factor Alpha (TNF-α)(p = 0.6), however age and aortic cross-clamp time were significant predictors of POAF development across all models.

Conclusions

Our study suggests no significant association exists between cytokine release patterns and the development of POAF. Age and Aortic Cross-clamp time were found to be significant predictors of POAF.

Usefulness of systemic immune-inflammation index in predicting atrial fibrillation recurrence after direct current cardioversion

Background: We aimed to determine whether there is a relationship between the systemic immune-inflammation (SII) index and the recurrence of atrial fibrillation (AF) after successful direct current cardioversion (DCCV). Methods: The study included 99 patients with persistent AF who underwent successful cardioversion between 2015 and 2020. Results: In multiple regression analyses, the SII index was found to be a better independent predictor of AF recurrence after successful DCCV (p < 0.001). The cut-off value of SII (563) was associated with 96.9% sensitivity and 55.2% specificity to predict AF recurrence after DCCV. Conclusion: As a simple biomarker, SII index is an independent parameter for predicting AF recurrence after successful DCCV in patients with persistent AF. Also, SII levels can predict AF recurrence better than neutrophil-to-lymphocyte ratio.

[Elevation of C-reactive protein early after cardiopulmonary bypass surgery is associated with occurrence of postoperative atrial fibrillation]

OBJECTIVE

To explore the association between postoperative C-reactive protein (CRP) levels and the occurrence of postoperative atrial fibrillation in patients undergoing cardiopulmonary bypass surgery.

METHODS

We retrospectively analyzed the data of 550 patients undergoing cardiopulmonary bypass surgery in our hospital from September, 2018 to May, 2021, and after screening against the exclusion criteria, 363 patients were selected for further analysis. Univariate analysis was used to analyze the correlation of age and early postoperative CRP level with the occurrence of postoperative atrial fibrillation, and Chi-square test was used to explore the correlation of gender, disease type, and comorbidity with postoperative atrial fibrillation followed by multivariate analysis of the data using a binary logistic regression model.

RESULTS

The 363 patients enrolled in this study included 247 with valvular disease, 42 with aortic dissection, 37 with coronary heart disease, and 37 with congenital heart disease, with a median postoperative CRP level of 88.65 mg/L and a median age of 57 years (range 5-77 years). Postoperative atrial fibrillation occurred in 101 (27.82%) of the patients, who were subsequently divided into atrial fibrillation group and sinus group. Univariate and multivariate correlation analyses showed that early postoperative elevation of CRP level was an important factor contributing to the occurrence of postoperative atrial fibrillation.

CONCLUSION

Early postoperative elevation of CRP level is associated with the occurrence of atrial fibrillation following cardiopulmonary bypass surgery.

Synovial fluid proteome profile of surgical versus chemical induced osteoarthritis in rabbits

BACKGROUND

Animal models are significant for understanding human osteoarthritis (OA). This study compared the synovial fluid proteomics changes in surgical and chemical induced OA models.

METHODS

Thirty rabbits either had anterior cruciate ligament transection (ACLT) procedure or injected intra-articularly with monosodium iodoacetate (MIA, 8 mg) into the right knee. The joints were anatomically assessed, and the synovial fluid proteins analyzed using two-dimensional polyacrylamide gel electrophoresis (2DGE) and MALDI TOF/TOF mass spectrometry analysis at 4, 8 and 12 weeks. The proteins' upregulation and downregulation were compared with control healthy knees.

RESULTS

Seven proteins (histidine-rich glycoprotein, beta-actin-like protein 2 isoform X1, retinol-binding protein-4, alpha-1-antiproteinase, gelsolin isoform, serotransferrin, immunoglobulin kappa-b4 chain-C-region) were significantly expressed by the surgical induction. They characterized cellular process (27%), organization of cellular components or biogenesis (27%), localization (27%) and biological regulation (18%), which related to synovitis, increased cellularity, and subsequently cartilage damage. Three proteins (apolipoprotein I-IV precursor, serpin peptidase inhibitor and haptoglobin precursor) were significantly modified by the chemical induction. They characterized stimulus responses (23%), immune responses (15%), biological regulations (15%), metabolism (15%), organization of cellular components or biogenesis (8%), cellular process (8%), biological adhesions (8%) and localization (8%), which related to chondrocytes glycolysis/death, neovascularization, subchondral bone necrosis/collapse and inflammation.

CONCLUSIONS

The surgical induced OA model showed a wider range of protein changes, which were most upregulated at week 12. The biological process proteins expressions showed the chemical induced joints had slower OA progression compared to surgical induced joints. The chemical induced OA joints showed early inflammatory changes, which later decreased.

Interleukin-6-Mediated-Ca2+ Handling Abnormalities Contributes to Atrial Fibrillation in Sterile Pericarditis Rats

Pre-existing Ca²⁺ handling abnormalities constitute the arrhythmogenic substrate in patients developing postoperative atrial fibrillation (POAF), a common complication after cardiac surgery. Postoperative interleukin (IL)-6 levels are associated with atrial fibrosis in several animal models of POAF, contributing to atrial arrhythmias. Here, we hypothesize that IL-6-mediated-Ca²⁺ handling abnormalities contribute to atrial fibrillation (AF) in sterile pericarditis (SP) rats, an animal model of POAF. SP was induced in rats by dusting atria with sterile talcum powder. Anti-rat-IL-6 antibody (16.7 μg/kg) was administered intraperitoneally at 30 min after the recovery of anesthesia. In vivo electrophysiology, ex vivo optical mapping, western blots, and immunohistochemistry were performed to elucidate mechanisms of AF susceptibility. IL-6 neutralization ameliorated atrial inflammation and fibrosis, as well as AF susceptibility in vivo and the frequency of atrial ectopy and AF with a reentrant pattern in SP rats ex vivo. IL-6 neutralization reversed the prolongation and regional heterogeneity of Ca²⁺ transient duration, relieved alternans, reduced the incidence of discordant alternans, and prevented the reduction and regional heterogeneity of the recovery ratio of Ca²⁺ transient. In agreement, western blots showed that IL-6 neutralization reversed the reduction in the expression of ryanodine receptor 2 (RyR2) and phosphorylated phospholamban. Acute IL-6 administration to isolated rat hearts recapitulated partial Ca²⁺ handling phenotype in SP rats. In addition, intraperitoneal IL-6 administration to rats increased AF susceptibility, independent of fibrosis. Our results reveal that IL-6-mediated-Ca²⁺ handling abnormalities in SP rats, especially RyR2-dysfunction, independent of IL-6-induced-fibrosis, early contribute to the development of POAF by increasing propensity for arrhythmogenic alternans.

A Prediction Rule Including Interleukin-6 in Pericardial Drainage Improves Prediction of New-Onset Atrial Fibrillation After Coronary Artery Bypass Grafting

OBJECTIVE

To test the hypothesis that a prediction rule including levels of interleukin-6 in pericardial drainage (pdIL-6) would improve the discrimination in classifying patients undergoing coronary artery bypass grafting (CABG) into different postoperative atrial fibrillation (POAF) risk levels.

DESIGN

Prospective cohort study.

SETTING

A university-affiliated tertiary hospital.

PARTICIPANTS

Patients undergoing CABG.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We prospectively recruited patients who underwent CABG into derivation and validation cohorts. The independent predictors were identified in the derivation cohort using multiple logistic regression and tested in the validation cohort. The performance of the predictive model was tested using area under the receiver operating characteristic curve (AUC) in both cohorts. A prediction rule was created by assigning points to each predictor. Patients were classified in various risk levels according to their total risk scores. We enrolled 302 and 207 patients in the derivation and validation cohorts, respectively. Multiple logistic regression analysis identified six predictors: age ≥61 y, left atrial diameter ≥49 mm, right atrial diameter ≥45 mm, number of grafts ≥3, and serum uric acid ≥226 µmol/L and pdIL-6 levels ≥166 ng/mL at postoperative 12 h. The AUC of the model was 0.78 and 0.77 for the derivation and validation cohort, respectively, which was greatly increased by adding pdIL-6. Patients were stratified into low-risk, moderate-risk and high-risk groups.

CONCLUSIONS

A POAF prediction rule including pdIL-6 had good performance for stratifying CABG patients into various risk groups for POAF. The inclusion of pdIL-6 resulted in clinically meaningful improvement in risk prediction.

Blood-based 8-hydroxy-2'-deoxyguanosine level: A potential diagnostic biomarker for atrial fibrillation

BACKGROUND

Recent research findings have revealed a key role of oxidative DNA damage in the pathogenesis of atrial fibrillation (AF). Therefore, the circulating oxidative DNA damage marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) may represent a biomarker for staging AF and identifying patients at risk for AF recurrence and postoperative atrial fibrillation (POAF) after treatment.

OBJECTIVE

The purpose of this study was to investigate whether serum levels of 8-OHdG correlate with the stage of AF, recurrence after AF treatment, and onset of POAF after cardiac surgery.

METHODS

In this prospective observational study, 8-OHdG levels were detected by enzyme-linked immunosorbent assay in human serum samples. Blood samples were collected from control patients without AF history; patients with paroxysmal AF and persistent AF undergoing electrical cardioversion or pulmonary vein isolation (PVI); and patients with sinus rhythm (SR) undergoing cardiac surgery. AF recurrence was determined during 12-month follow-up. Univariate and multivariate analyses were used to identify changes in 8-OHdG levels between the groups.

RESULTS

Compared to the control group, 8-OHdG levels in the patient groups gradually and significantly increased during arrhythmia progression. 8-OHdG levels in AF patients showing AF recurrence after PVI treatment were significantly increased compared to patients without AF recurrence. Moreover, in SR patients undergoing cardiac surgery, 8-OHdG levels were significantly elevated in those showing POAF compared to patients without POAF.

CONCLUSION

8-OHdG level may represent a potential diagnostic biomarker for AF staging as well as for predicting AF recurrence and POAF after treatment.

Predictive values of C-reactive protein/albumin ratio in new-onset atrial fibrillation after coronary artery bypass grafting

OBJECTIVE

This study aimed to investigate the predictive value of the newly defined C-Reactive Protein (CRP)/Albumin Ratio (CAR) in determining the development of atrial fibrillation (AF) in comparison with other inflammatory markers, such as Neutrophil/Lymphocyte (N/L) Ratio and Platelet/Lymphocyte (P/L) Ratio, in patients undergoing Coronary Artery Bypass Grafting (CABG) surgery.

METHODS

The population of this observational study consisted of 415 patients undergoing CABG. The study cohort was subdivided into two groups based on the development of AF. Complete blood counts, serum CRP, and serum albumin levels were evaluated before the CABG. The CAR, N/L, and P/L ratios of all the patients were calculated. Predictors of postoperative AF were determined by multiple logistic regression analysis (MLRA).

RESULTS

During follow-up, 136 patients (32.8%) developed postoperative AF. With MLRA, independent risk factors for postoperative AF were determined as follows: fasting glucose level (OR: 1.01; 95 % CI: 1.00-1.01, P <0.001), age (OR: 1.12; 95 % CI: 1.07-1.17, P <0.001), left ventricle ejection fraction (OR: 0.90; 95 % CI: 0.87-0.94, P <0.001), male gender (OR: 3.32; 95 % CI: 1.39-7.90, P = 0.007), 24-hour drainage amount (OR: 1.004; 95 % CI: 1.002-1.005, P <0.001), and CAR (OR: 1.82; 95 % CI: 1.53-2.16, P <0.001). Receiver Operating Characteristic curve analysis showed that CAR (C-statistic: 0.75; 95% CI: 0.71-0.79, p< 0.001) was a significant predictor of AF.

CONCLUSION

Novel inflammatory marker CAR can be used as a reliable marker to predict the development of AF following CABG.

Relationship between c-reactive protein/albumin ratio and new-onset atrial fibrillation after coronary artery bypass grafting

OBJECTIVE

This study aimed to investigate the predictive value of the newly defined C-Reactive Protein (CRP)/Albumin Ratio (CAR) in determining the development of atrial fibrillation (AF) in comparison with other inflammatory markers, such as Neutrophil/Lymphocyte (N/L) Ratio and Platelet/Lymphocyte (P/L) Ratio, in patients undergoing Coronary Artery Bypass Grafting (CABG) surgery.

METHODS

The population of this observational study consisted of 415 patients undergoing CABG. The study cohort was subdivided into two groups based on the development of AF. Complete blood counts, serum CRP, and serum albumin levels were evaluated before the CABG. The CAR, N/L, and P/L ratios of all the patients were calculated. Predictors of postoperative AF were determined by multiple logistic regression analysis (MLRA).

RESULTS

During follow-up, 136 patients (32.8%) developed postoperative AF. With MLRA, independent risk factors for postoperative AF were determined as follows: fasting glucose level (OR: 1.01; 95 % CI: 1.00-1.01, P <0.001), age (OR: 1.12; 95 % CI: 1.07-1.17, P <0.001), left ventricle ejection fraction (OR: 0.90; 95 % CI: 0.87-0.94, P <0.001), male gender (OR: 3.32; 95 % CI: 1.39-7.90, P = 0.007), 24-hour drainage amount (OR: 1.004; 95 % CI: 1.002-1.005, P <0.001), and CAR (OR: 1.82; 95 % CI: 1.53-2.16, P <0.001). Receiver Operating Characteristic curve analysis showed that CAR (C-statistic: 0.75; 95% CI: 0.71-0.79, p< 0.001) was a significant predictor of AF.

CONCLUSION

Novel inflammatory marker CAR can be used as a reliable marker to predict the development of AF following CABG.

Atrial Myocyte NLRP3/CaMKII Nexus Forms a Substrate for Postoperative Atrial Fibrillation

RATIONALE

Postoperative atrial fibrillation (POAF) is a common and troublesome complication of cardiac surgery. POAF is generally believed to occur when postoperative triggers act on a preexisting vulnerable substrate, but the underlying cellular and molecular mechanisms are largely unknown.

OBJECTIVE

To identify cellular POAF mechanisms in right atrial samples from patients without a history of atrial fibrillation undergoing open-heart surgery.

METHODS AND RESULTS

Multicellular action potentials, membrane ion-currents (perforated patch-clamp), or simultaneous membrane-current (ruptured patch-clamp) and [Ca²⁺]_i-recordings in atrial cardiomyocytes, along with protein-expression levels in tissue homogenates or cardiomyocytes, were assessed in 265 atrial samples from patients without or with POAF. No indices of electrical, profibrotic, or connexin remodeling were noted in POAF, but Ca²⁺-transient amplitude was smaller, although spontaneous sarcoplasmic reticulum (SR) Ca²⁺-release events and L-type Ca²⁺-current alternans occurred more frequently. CaMKII (Ca²⁺/calmodulin-dependent protein kinase-II) protein-expression, CaMKII-dependent phosphorylation of the cardiac RyR2 (ryanodine-receptor channel type-2), and RyR2 single-channel open-probability were significantly increased in POAF. SR Ca²⁺-content was unchanged in POAF despite greater SR Ca²⁺-leak, with a trend towards increased SR Ca²⁺-ATPase activity. Patients with POAF also showed stronger expression of activated components of the NLRP3 (NACHT, LRR, and PYD domains-containing protein-3)-inflammasome system in atrial whole-tissue homogenates and cardiomyocytes. Acute application of interleukin-1β caused NLRP3-signaling activation and CaMKII-dependent RyR2/phospholamban hyperphosphorylation in an immortalized mouse atrial cardiomyocyte cell-line (HL-1-cardiomyocytes) and enhanced spontaneous SR Ca²⁺-release events in both POAF cardiomyocytes and HL-1-cardiomyocytes. Computational modeling showed that RyR2 dysfunction and increased SR Ca²⁺-uptake are sufficient to reproduce the Ca²⁺-handling phenotype and indicated an increased risk of proarrhythmic delayed afterdepolarizations in POAF subjects in response to interleukin-1β.

CONCLUSIONS

Preexisting Ca²⁺-handling abnormalities and activation of NLRP3-inflammasome/CaMKII signaling are evident in atrial cardiomyocytes from patients who subsequently develop POAF. These molecular substrates sensitize cardiomyocytes to spontaneous Ca²⁺-releases and arrhythmogenic afterdepolarizations, particularly upon exposure to inflammatory mediators. Our data reveal a potential cellular and molecular substrate for this important clinical problem.

C-reactive protein after coronary artery bypass graft surgery and its relationship with postoperative atrial fibrillation

Aims

Postoperative atrial fibrillation (POAF), a common complication following coronary artery bypass graft (CABG) surgery, is associated with increased morbidity and mortality. Inflammation may be an important factor for the pathogenesis of POAF, and increased preoperative levels of C-reactive protein (CRP) are associated with the development of POAF. However, the relationship between postoperative CRP and POAF is less well established.

Methods and results

Patients undergoing first-time isolated CABG surgery (1 January 2000–31 December 2016) were identified using the Eastern Danish Heart Surgery Database and nationwide administrative registries. Patients with no history of atrial fibrillation and with available CRP measurements from postoperative day (POD) 4 were included. The study population was divided into quartiles based on CRP. The association between CRP levels and the odds of developing POAF was investigated using multivariable logistic regression analysis. We included 6711 patients. The CRP intervals on POD 4 for the CRP groups (lowest to highest) were ≤90, &gt;90 to ≤127, &gt;127 to ≤175, and &gt;175 mg/L, respectively. Patients in the highest CRP group were older and more often men compared with patients in the lowest CRP group [median age 67 years (P25–P75: 61–73) and 84.7% men vs. median age 64 years (P25–P75: 56–70) and 77.9% men]. In the lowest and highest CRP groups, 25% and 35% developed POAF, respectively. In adjusted analysis, the highest CRP group, compared with the lowest CRP group, was associated with greater odds of developing POAF (odds ratio 1.31; 95% confidence interval 1.12–1.54).

Conclusion

Increased postoperative CRP levels after CABG surgery was associated with the development of POAF.

Postoperative Atrial Fibrillation Following Cardiac Surgery: From Pathogenesis to Potential Therapies

Postoperative atrial fibrillation (POAF) is a major complication after cardiac surgery which can lead to high rates of morbidity and mortality, an enhanced length of hospital stay, and an increased cost of care. POAF is postulated to be a multifactorial phenomenon; however, some major pathogeneses have been proposed, including inflammatory pathways, oxidative stress, and autonomic dysfunction. Genetic studies also showed that inflammatory pathways, beta-1 adrenoreceptor variants, G protein-coupled receptor kinase 5 gene variants, and non-coding single-nucleotide polymorphisms in the 4q25 chromosomal locus are involved in this phenomenon. Moreover, several predisposing factors lead to the development of POAF, consisting of pre-, intra-, and postoperative contributors. The main predisposing factors comprise age, prior history of major cardiovascular risk factors, and ischemia-reperfusion injury during surgery. The management of POAF is based on the usual therapies used for non-surgical AF, including medications for either rate control or rhythm control in hemodynamically unstable patients. The perioperative administration of β-blockers and some antiarrhythmic agents has been recommended in major international guidelines. In addition, upstream therapies consisting of colchicine, magnesium, statins, and antioxidants have attenuated the incidence of POAF; however, some uncomfortable side effects developed in large randomized trials. The use of anticoagulation has also resulted in less mortality in patients with POAF at higher risk of thromboembolic events. Despite these recommendations, the actual regimen for the prevention of POAF remains controversial. In this review, we highlight the pathogenesis, predisposing factors, and potential therapeutic options for the management of patients at risk for or with POAF following cardiac surgery.

Perioperative Biomarkers Predicting Postoperative Atrial Fibrillation Risk After Coronary Artery Bypass Grafting: A Narrative Review

Postoperative atrial fibrillation (POAF) after cardiac surgery remains a highly prevalent and costly condition that negatively impacts patient quality of life and survival. Numerous retrospective studies, meta-analysis, and review papers have been reported identifying POAF risk based on patients' risk factors and clinical biomarkers. In this narrative review, the authors report significant variations among selected pre- and perioperative biomarkers used to predict POAF incidence in patients without a history of atrial fibrillation (AF). POAF prediction based on B-type natriuretic peptide, N-terminal pro B-type natriuretic peptide, C-reactive protein, interleukin-6, creatinine, and plasminogen activator inhibitor-1 differs significantly among different studies, thereby limiting their clinical utility to predict POAF risk with high accuracy. Conversely, soluble vascular endothelial cells adhesion molecule-1, soluble CD40 ligand, Galectin-3, and aldosterone show promise for better POAF prediction. However, the current datasets for these selected biomarkers are not of sufficient size to validate the broad clinical application specifically for patients with no prior history of AF.

IL-6 Rapidly Induces Reversible Atrial Electrical Remodeling by Downregulation of Cardiac Connexins

See Article Lazzerini et al

What is the role of metabolic syndrome and obesity for postoperative atrial fibrillation after coronary bypass grafting?

BACKGROUND

Postoperative atrial fibrillation is the most common arrhythmia seen after cardiac surgery. We aimed to determine the effect of obesity and metabolic syndrome on postoperative atrial fibrillation, whether they are independent risk factors, and their effect level. We also analyzed the effect of atrial fibrillation on postoperative complications.

METHODS

In our clinic, 756 patients who underwent coronary artery bypass grafting between June 2010-September 2017 were evaluated retrospectively. Preoperatively, demographic characteristics, chronic diseases, body mass index, waist circumference measurements, and ejection fraction values of the cases were determined from file records. Perioperatively, cross-clamp and cardiopulmonary bypass times, intra-aortic balloon use, distal coronary bypass counts were determined. Postoperatively, complications, duration of intensive care unit and hospital stay, and mortality were evaluated. The patients were followed up with continuous 3-lead ECG monitorization on the postoperative first day and 12-lead ECG records once in a day on the remaining days. In the study, the first endpoint was the determination of atrial fibrillation and the second endpoint was the discharge time of the patient.

RESULTS

The rate of postoperative atrial fibrillation was 21.3%. Atrial fibrillation was seen in 33% of metabolic syndrome cases and in 38.5% of obese cases. Atrial fibrillation was seen in 23, 24 and 17% of cases using statin, ACE inhibitor and beta blocker, respectively. It was seen in 21% of smokers and 20% of the COPD cases. In the study, metabolic syndrome, diabetes mellitus, hypertension, and obesity, between the ages of 56-78 with Metabolic syndrome, were found to affect the development of postoperative atrial fibrillation (2.46), (2.3), (1.6), and (1.65) times, respectively. In cases with postoperative atrial fibrillation, infection and stroke were 1.45 and 8.85 times more frequent, respectively. Patients with metabolic syndrome were found to have 31% longer hospital stay, and 17% higher infection rate. In obese patients, hospitalization was 23.5% longer.

CONCLUSIONS

Metabolic syndrome and obesity were found to be two independent risk factors for postoperative atrial fibrillation. If causes and mechanisms of postoperative atrial fibrillation are identified in planned cardiovascular interventions, we believe that cost of hospitalization and morbidity will be reduced.

Cardiolipotoxicity, Inflammation, and Arrhythmias: Role for Interleukin-6 Molecular Mechanisms

Fatty acid infiltration of the myocardium, acquired in metabolic disorders (obesity, type-2 diabetes, insulin resistance, and hyperglycemia) is critically associated with the development of lipotoxic cardiomyopathy. According to a recent Presidential Advisory from the American Heart Association published in 2017, the current average dietary intake of saturated free-fatty acid (SFFA) in the US is 11–12%, which is significantly above the recommended <10%. Increased levels of circulating SFFAs (or lipotoxicity) may represent an unappreciated link that underlies increased vulnerability to cardiac dysfunction. Thus, an important objective is to identify novel targets that will inform pharmacological and genetic interventions for cardiomyopathies acquired through excessive consumption of diets rich in SFFAs. However, the molecular mechanisms involved are poorly understood. The increasing epidemic of metabolic disorders strongly implies an undeniable and critical need to further investigate SFFA mechanisms. A rapidly emerging and promising target for modulation by lipotoxicity is cytokine secretion and activation of pro-inflammatory signaling pathways. This objective can be advanced through fundamental mechanisms of cardiac electrical remodeling. In this review, we discuss cardiac ion channel modulation by SFFAs. We further highlight the contribution of downstream signaling pathways involving toll-like receptors and pathological increases in pro-inflammatory cytokines. Our expectation is that if we understand pathological remodeling of major cardiac ion channels from a perspective of lipotoxicity and inflammation, we may be able to develop safer and more effective therapies that will be beneficial to patients.

Usefulness of platelet to lymphocyte ratio for predicting recurrence of atrial fibrillation after direct current cardioversion

OBJECTIVE

Atrial fibrillation (AF) is the most common cardiac rhythm disorder with the associated risks of stroke and mortality. The usefulness of platelet to lymphocyte ratio (PLR), a recently described inflammatory marker, in predicting adverse cardiovascular events has been demonstrated in several studies. In the current study, we investigated the role of PLR in predicting recurrence after successful electrical cardioversion (ECV) in patients with non-valvular persistent AF.

METHODS

A total of 287 patients with non-valvular persistent AF achieving restoration of the sinus rhythm after successful ECV were included in this study. At study entry, complete blood count, routine biochemistry tests, and transthoracic echocardiography (TTE) were performed routinely in all subjects. Patients were followed up for 6 months following the procedure and comparisons were performed between patients who recurred and who maintained the sinus rhythm (SR).

RESULTS

At 6 months of follow-up, AF recurred in 108 patients, corresponding to a recurrence rate of 39%. Mean PLR values in the "AF recurrence group" (mean age 57.4 ± 12.0 years, 47.6% [n = 80] female) and in "SR maintenance" group (mean age 65.0 ± 9.4 years, 55.6% [n = 60] female) were 184.8 ± 44.2 and 103.3 ± 44.2, respectively, with a significant difference between the two groups (p < 0.001). In multiple regression analyses, PLR emerged as a risk factor associated with AF recurrence during the 6-month follow-up period after successful ECV (odds ratio [OR]: 3.029 (1.013-9.055 95% confidence interval [CI]), p = 0.047). When a cutoff value of 147 was used, the sensitivity and specificity of PLR for predicting AF recurrence were 83.3% and 84.5%, respectively.

CONCLUSION

Elevated PLR is a marker of increased inflammation and may serve as a practical and inexpensive predictor for recurrence during 6 months of follow-up in patients with non-valvular persistent AF who had restoration of the sinus rhythm after successful ECV.

Blood transfusion and risk of atrial fibrillation after coronary artery bypass graft surgery: A meta-analysis of cohort studies

The aim of this study was to systematically evaluate the effect of blood transfusion (BT) on postoperative atrial fibrillation (AF) in adult patients who had undergone coronary artery bypass grafting (CABG) surgery.PubMed, Embase, and Cochrane Library databases from inception to January 2017 were searched. Cohort studies were searched that evaluated the association between BT and the risk of postoperative AF in adult patients who had undergone CABG surgery. Study quality was assessed by using the Newcastle-Ottawa scale (NOS). A meta-analysis was performed with the random-effect model.Eight cohort studies involving 7401 AF cases and 31,069 participants were identified and included in our data analysis. The pooled odds ratio of postoperative AF in patients with BT was 1.45 (95% confidence interval, 1.26-1.67), with significant heterogeneity (P < .0001, I = 79%). Excluding one study that had an off-pump CABG did not significantly impact this result (odds ratio, 1.36; 95% confidence interval, 1.23-1.50; n = 7). To examine the stability of the primary results, we performed subgroup analyses. The association between BT and the risk of postoperative AF was similar, as determined in the stratified analyses conducted according to study design, type of surgery, and country.The findings of the present meta-analysis demonstrated a statistically significant increase in postoperative AF risk among adult patients with BT. Further prospective large-scale studies are needed to establish causality and to elucidate the underlying mechanisms.

The Pathophysiology of Cardiac Surgery-Associated Acute Kidney Injury (CSA-AKI)

Cardiac surgery associated acute kidney injury (CSA-AKI) is a significant clinical problem. Its pathogenesis is complex and multifactorial. It likely involved at least six major injury pathways: exogenous and endogenous toxins, metabolic factors, ischemia and reperfusion, neurohormonal activation, inflammation and oxidative stress. These mechanisms of injury are likely to be active at different times with different intensity and probably act synergistically. Because of such complexity and the small number of randomised controlled investigations in this field only limited recommendations can be made. Nonetheless, it appears important to avoid nephrotoxic drugs and desirable to avoid hyperglycemia in the peri-operative period. The duration of cardiopulmonary bypass should be limited whenever possible. Off-pump surgery, when indicated, may decrease the risk of AKI. Invasive hemodynamic monitoring focussed on attention to maintaining euvolemia, an adequate cardiac output and an adequate arterial blood pressure is desirable. Echocardiography may be useful in minimizing atheroembolic complications. The administration of N-acetylcysteine to protect the kidney from oxidative stress is not recommended. There is marked lack of randomised controlled trials in this field.

Minimally invasive heart valve surgery: influence on coagulation and inflammatory response

OBJECTIVES

Minimally invasive valve surgery (MIVS) is associated with improved clinical outcome but longer cardiopulmonary bypass (CPB) time. The aim of the present study is to compare inflammatory and coagulation parameters in patients undergoing minimally invasive or standard valve surgery.

METHODS

A prospective non-randomized study was performed enrolling 79 patients undergoing mitral (20 right mini-thoracotomy and 18 standard sternotomy) and aortic valve (20 mini-sternotomy and 21 standard sternotomy) procedures. Blood samples were collected perioperatively to measure prothrombin fragment 1.2 (PF1.2, thrombin generation), plasmin antiplasmin complex (PAP, fibrinolysis), interleukin-6 (IL-6, inflammation). Plasma free haemoglobin (f-Hb) was assessed to evaluate haemolysis.

RESULTS

Patients in the minimally invasive group were younger and had less comorbidities CPB and cross-clamp times were comparable considering both aortic and mitral procedures, but longer in the mini-thoracotomy group. IL-6 and PAP were reduced in the minimally invasive group, particularly 2 h after CPB (respectively 102 ± 114 vs 34 ± 49 pg/ml, P < 0.001 and 2137 ± 1046 vs 1207 ± 675 ng/ml, P < 0.001), PF1.2 was also reduced during and after the operation (688 ± 514 vs 571 ± 470, P = 0.02; 1600 ± 1185 vs 1042 ± 548, P < 0.001; 1487 ± 676 vs 1042 ± 541). Despite the use of vacuum-assisted active venous drainage (VAVD) f-Hb was significantly reduced in the minimally invasive group. The other routine biomarkers such as C-reactive protein, fibrinogen and cTnI were also reduced in the minimally invasive group.

CONCLUSIONS

In a selected cohort of patients MIVS is associated to reduced inflammatory reaction and coagulopathy, supporting the clinical evidence of reduced postoperative bleeding and lower transfusion rate. Our data offer further suggestion supporting the adoption of minimally invasive approaches.

Signal Transducer and Activator of Transcription 3/MicroRNA-21 Feedback Loop Contributes to Atrial Fibrillation by Promoting Atrial Fibrosis in a Rat Sterile Pericarditis Model

Supplemental Digital Content is available in the text.

Background—

Postoperative atrial fibrillation is a frequent complication in cardiac surgery. The aberrant activation of signal transducer and activator of transcription 3 (STAT3) contributes to the pathogenesis of atrial fibrillation. MicroRNA-21 (miR-21) promotes atrial fibrosis. Recent studies support the existence of reciprocal regulation between STAT3 and miR-21. Here, we test the hypothesis that these 2 molecules might form a feedback loop that contributes to postoperative atrial fibrillation by promoting atrial fibrosis.

Methods and Results—

A sterile pericarditis model was created using atrial surfaces dusted with sterile talcum powder in rats. The inflammatory cytokines interleukin (IL)-1β, IL-6, transforming growth factor-β, and tumor necrosis factor-α, along with STAT3 and miR-21, were highly upregulated in sterile pericarditis rats. The inhibition of STAT3 by S3I-201 resulted in miR-21 downregulation, which ameliorated atrial fibrosis and decreased the expression of the fibrosis-related genes, α-smooth muscle actin, collagen-1, and collagen-3; reduced the inhomogeneity of atrial conduction; and attenuated atrial fibrillation vulnerability. Meanwhile, treatment with antagomir-21 decreased STAT3 phosphorylation, alleviated atrial remodeling, abrogated sterile pericarditis–induced inhomogeneous conduction, and prevented atrial fibrillation promotion. The culturing of cardiac fibroblasts with IL-6 resulted in progressively augmented STAT3 phosphorylation and miR-21 levels. S3I-201 blocked IL-6 induced the expression of miR-21 and fibrosis-related genes in addition to cardiac fibroblast proliferation. Transfected antagomir-21 decreased the IL-6–induced cardiac fibroblast activation and STAT3 phosphorylation. The overexpression of miR-21 in cardiac fibroblasts caused the upregulation of STAT3 phosphorylation, enhanced fibrosis-related genes, and increased cell numbers.

Conclusions—

Our results have uncovered a novel reciprocal loop between STAT3 and miR-21 that is activated after heart surgery and can contribute to atrial fibrillation.

Meta-analysis Identifies Serum C-Reactive Protein as an Indicator of Atrial Fibrillation Risk After Coronary Artery Bypass Graft

A meta-analysis-based study was conducted to examine the clinical value of serum C-reactive protein (CRP) levels in predicting postoperative atrial fibrillation (POAF) in patients with coronary artery disease (CAD) who underwent coronary artery bypass graft. Computer-based search of scientific literature databases was performed to identify relevant studies in strict accordance with our inclusion and exclusion criteria. Data extracted from the selected studies were used to perform meta-analysis using the STATA 12.0 statistical software. Standardized mean differences (SMDs) with their 95% confidence interval (95% CI) were calculated. The database search strategy initially identified 62 articles (Chinese = 17, English = 45). After multiple levels of screening and validation, 15 case-control studies (Chinese = 1, English = 14), containing of a total of 3110 atrial fibrillation patients (POAF = 925, non-POAF = 2185), were selected for our meta-analysis. The meta-analysis results confirmed that serum CRP level was remarkably higher in patients with POAF compared with non-POAF (SMD = 1.36; 95% CI, 0.44-2.28; P = 0.004). Ethnicity-stratified analysis revealed that elevated serum CRP levels were associated with an increased risk of POAF in white patients with CAD (SMD = 0.85; 95% CI, 0.12-1.58; P = 0.022), but not Asian patients with CAD (SMD = 3.31, 95% CI, -0.04 to 6.66; P = 0.053). Elevated CRP levels, indicating profound inflammation, may be associated with significantly increased risk of POAF in patients with CAD who underwent coronary artery bypass graft. Thus, serum CRP levels are important for early diagnosis and monitoring of POAF in high-risk patients.

Cytokine Effects on Mechano-Induced Electrical Activity in Atrial Myocardium

The role of cytokines as regulators of stretch-related mechanisms is of special importance since mechano-sensitivity plays an important role in a wide variety of biological processes. Here, we elucidate the influence of cytokine application on mechano-sensitivity and mechano-transduction. The atrial myocardial stretch induces production of interleukin (IL)-2, IL-6, IL-13, IL-17A, and IL-18 with exception of tumor necrosis factor α (TNF-α), IL-1β, and vascular endothelial growth factor B (VEGF-B). Positive ionotropic effect was specific for VEGF-B, negative ionotropic effects were specific for TNF-α, IL-1β, IL-2, IL-6, IL-13, IL-17A and IL-18, while IL-1α doesn't show direct ionotropic effect. The IL-2, IL-6, IL-17A, IL-18, and VEGF-B cause elongation of the APD, in comparison with the reduced APD caused by the IL-13. The TNF-α, IL-1β, and IL-18 influences L-type Ca²⁺ channels, IL-2 has an inhibitory effect on the fast Na⁺ channels while IL-17A and VEGF-B were specific for Kir channels. With exception of the IL-1α, IL-2, and VEGF-B, all analyzed cytokines include nitric oxide dependent signaling with resultant combined effects on mechano-gated and Ca²⁺ channels. The relationships between these pathways and the time-dependence of their activation are of important considerations in the evaluation of cytokine-induced electrical abnormality, specific for cardiac dysfunctions. In general, the discussion presented in this review covers research devoted to counterbalance between different cytokines in the regulation of stretch-induced effects in rat atrial myocardium.

ABBREVIATIONS

APs: action potentials; APD25: action potential durations to 25% of re-polarization; APD50: action potential durations to 50% of repolarization; APD90: action potential durations to 90% of repolarization; MGCs: mechanically gated channels.

Serum interleukin-6: Association with circulating cytokine serum levels in patients with sinus arrhythmia and patients with coronary artery disease

In this study, we were focused on the differences between certain circulating cytokine levels in patients with or without sinus arrhythmia, according to the median IL-6 level. All patients were stable with regards to symptoms and therapy for at least one month prior to the measurements conducted within this study.Exclusion criteria were: patients with sleep apnea, asthma, respiratory insufficiency of any genesis, active infection, allergy, inflammatory diseases, cancer, diabetes of any type and treatment with anti-inflammatory drugs. The study was approved by the Institutional Review Board. All recruited patients gave their verbal and written consent for participation in the study. The study group consisted of 74 patients divided into two groups: with (38) and without sinus arrhythmia but with diagnosed coronary artery disease (36). Sinus arrhythmia was confirmed by 24h Holter monitoring. From all test parameters only cytokines IL-2, IL-8, IL-10, IL-17 and IL-18, showed statistically significant increasing in patients with statistically higher IL-6 levels. It is possible that IL-6 may not be a marker for the selection of patients with sinus arrhythmia or coronary artery disease. The findings indicate that IL-6 represents a reliable indicator for increased expression of IL-2, IL-8, IL-10, IL-17 and IL-18 in patients with sinus arrhythmia or coronary artery disease. Further studies in a large number of patients would be necessary to confirm our observations.

Inflammation, oxidative stress and postoperative atrial fibrillation in cardiac surgery

Postoperative atrial fibrillation (POAF) is a common complication of cardiac surgery that occurs in up to 60% of patients. POAF is associated with increased risk of cardiovascular mortality, stroke and other arrhythmias that can impact on early and long term clinical outcomes and health economics. Many factors such as disease-induced cardiac remodelling, operative trauma, changes in atrial pressure and chemical stimulation and reflex sympathetic/parasympathetic activation have been implicated in the development of POAF. There is mounting evidence to support a major role for inflammation and oxidative stress in the pathogenesis of POAF. Both are consequences of using cardiopulmonary bypass and reperfusion following ischaemic cardioplegic arrest. Subsequently, several anti-inflammatory and antioxidant drugs have been tested in an attempt to reduce the incidence of POAF. However, prevention remains suboptimal and thus far none of the tested drugs has provided sufficient efficacy to be widely introduced in clinical practice. A better understanding of the cellular and molecular mechanisms responsible for the onset and persistence of POAF is needed to develop more effective prediction and interventions.

Postoperative atrial fibrillation: role of inflammatory biomarkers and use of colchicine for its prevention

Postoperative atrial fibrillation (POAF) is the most common complication following cardiac surgery, occurring in up to 65% of cardiac surgical patients. It is a condition associated with increased morbidity, increased length of hospital stay, and increased health care costs. One of the many potential causes of POAF is postsurgical inflammation, as demonstrated by increased levels of inflammatory biomarkers such as C-reactive protein and interleukin-6. Although still a subject of debate, the role of these inflammatory markers in the pathogenesis of POAF remains under vigorous investigation. Several antiinflammatory drugs have demonstrated promising results in prevention of POAF, including nonsteroidal antiinflammatory drugs, glucocorticoids, and statins. Colchicine is one of the oldest medications used in modern medicine, typically for the treatment and prevention of gout. New evidence has recently surfaced that colchicine may also be useful in the prevention of POAF. In recent studies, colchicine has demonstrated both safety and efficacy in the prevention of POAF. Several new studies are currently being initiated that may further elucidate colchicine's role in the prevention of POAF.

Inflammation in new-onset atrial fibrillation after cardiac surgery: a systematic review

BACKGROUND

Postoperative new-onset atrial fibrillation (PNAF) is the most common complication following cardiac surgery. The pathogenesis of PNAF is multifactorial. The concept of the postoperative inflammatory response, as a potential underlying mechanism has been extensively studied. This review aims to provide a comprehensive summary of literature relevant to the association between the inflammatory response following cardiac surgery and PNAF.

DESIGN

MEDLINE, EMBASE and the Cochrane Central Register were systematically reviewed by two independent investigators for studies published between January 1980 and May 2012, in which an association between serum markers of inflammation and PNAF was evaluated, or the effect of drugs with anti-inflammatory properties on the risk of PNAF.

RESULTS

Sixty-three studies met selection criteria (39 observational and 24 randomized studies) including 27,363 patients. The mean incidence of PNAF after cardiac surgery was 25·5%. Elevated levels of various inflammatory mediators were associated with PNAF, and the most consistent association was found between white blood cell count and PNAF. Of the drugs with anti-inflammatory properties, statins gave the best protective effect against PNAF, followed by anti-oxidants, steroids and colchicine. Nonsteroidal anti-inflammatory drugs did not prevent PNAF significantly.

CONCLUSION

The postoperative inflammation response may play a role in the pathogenesis of PNAF. However, of the inflammation biomarkers, only elevated white blood cell count reliably predicts PNAF. Pre- and perioperative use of statins and several other drugs with anti-inflammatory properties reduce the incidence of PNAF.

Inflammation, Functional Status, and Weight Loss During Recovery From Cardiac Surgery in Older Adults

Objective:

To determine the nutritional, inflammatory, and functional aspects of unintentional weight loss after cardiac surgery that warrant further investigation.

Research Methods and Procedures:

Twenty community-dwelling adults > 65 years old undergoing cardiac surgery (coronary artery bypass graft [CABG] or CABG + valve) were recruited for this prospective longitudinal (preoperative and 4–6 weeks postdischarge) pilot study. Anthropometrics (weight, standing height, and mid-arm and calf circumference), nutritional status (Mini-Nutritional Assessment™ [MNA]), appetite, physical performance (timed chair stand), muscle strength (hand grip) and functional status (basic and instrumental activities of daily living), and inflammatory markers (plasma leptin, ghrelin, interleukin [IL]-6, high-sensitivity[hs] C-reactive protein, and serum albumin and prealbumin) were measured.

Results:

Participants who completed the study ( n = 11 males, n = 3 females) had a mean age 70.21 ± 4.02 years. Of these, 12 lost 3.66 ± 1.44 kg over the study period. Weight, BMI, activities of daily living, and leptin decreased over time ( p < .05). IL-6 increased over time ( p < .05). Ghrelin, hs-CRP, and timed chair stand increased over time in those who underwent combined procedures ( p < .05). Grip strength decreased in those who developed complications ( p = .004). Complications, readmission status, and lowered grip strength were found in those with low preoperative MNA scores ( p < .05).

Conclusion:

After cardiac surgery, postdischarge weight loss occurs during a continued inflammatory response accompanied by decreased physical functioning and may not be a positive outcome. The impacts of weight loss, functional impairment, and inflammation during recovery on disability and frailty warrant further study.

Plasma leptin levels increase to a greater extent following on-pump coronary artery surgery in type 2 diabetic patients than in nondiabetic patients

AIMS

We aimed to evaluate whether leptin and ghrelin responses to cardiopulmonary bypass (CPB) are dependent on type 2 diabetes and whether these responses are associated with interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP), cortisol and insulin.

METHODS

We examined stress-response patterns in plasma leptin, ghrelin, hsCRP, IL-6, cortisol and insulin levels before and up to 5 days after cardiopulmonary bypass in 20 patients with type 2 diabetes and 20 patients without diabetes.

RESULTS

Plasma leptin levels increased significantly in both groups (p<0.05) and rose significantly higher in diabetics when compared with nondiabetic patients (p=0.004). Plasma ghrelin levels increased significantly only in diabetics (p=0.033). Patients with and without diabetes showed significantly elevated serum concentrations of IL-6, hsCRP, cortisol and insulin (p<0.005 for IL-6, hsCRP; p<0.05 for cortisol, insulin) but the difference between the two groups was nonsignificant. Leptin was independently predicted by hsCRP (p<0.05, F=2.9), gender (women p<0.001, F=4.7), body mass index (BMI p<0.0001, F=6.1) whereas ghrelin levels were not associated with any variables in the total patient population. (critical F=2.26, p≤0.05).

CONCLUSIONS

Acute phase response in diabetics differs by higher leptin levels independent of BMI, gender and IL-6, hsCRP, insulin and cortisol levels.

Impaired cardiac autophagy in patients developing postoperative atrial fibrillation

OBJECTIVES

Postoperative atrial fibrillation (POAF) is a common complication after on-pump heart surgery. Several histologic abnormalities, such as interstitial fibrosis and vacuolization, have been described in atrial samples from patients developing POAF. This ultrastructural remodeling has been associated with the establishment of a proarrhythmic substrate. We studied whether atrial autophagy is activated in patients who develop POAF.

METHODS

A total of 170 patients in sinus rhythm who had undergone elective coronary artery bypass grafting were included. Systemic inflammatory markers were measured at baseline and 72 hours after surgery. During the procedure, samples of the right atrial appendages were obtained for evaluation of remodeling by light and electron microscopy. Protein ubiquitination and autophagy-related LC3B processing were assessed by Western blot.

RESULTS

Of these patients, 22% developed POAF. The level of high-sensitivity C-reactive protein, fibrosis, inflammation, myxoid degeneration, and ubiquitin-aggregates in the atria did not differ between patients with and without POAF. Electron microphotographs of those with POAF showed a significant accumulation of autophagic vesicles and lipofuscin deposits. Total protein ubiquitination was similar in the patients with and without POAF, but LC3B processing was markedly reduced in those with POAF, suggesting a selective impairment in autophagic flow.

CONCLUSIONS

This study provides novel evidence that ultrastructural atrial remodeling characterized by an impaired cardiac autophagy is present in patients developing POAF after coronary artery bypass surgery.

[Cardiac biomarkers in perioperative risk stratification]

OBJECTIVES

The field of new cardiac biomarkers has triggered physicians' enthusiasm because of their potential diagnostic and prognostic values for routine clinical practice in the surgical setting. The objective of the present article is to review the role of new cardiac biomarkers and their potential additive clinical value in predicting short- and long-term risk following cardiac and non-cardiac surgery.

DATA SOURCES

A PubMed(®) database research in English and French languages published until June 2010. Keywords were cardiac biomarkers, troponins, cardiac troponin I (cTnI), natriuretic peptides, B-type natriuretic peptide (BNP), C-reactive protein (CRP), multiple markers approach, risk stratification, clinical risk scores.

DATA SYNTHESIS

Numerous publications deal with the diagnostic and prognostic values of new cardiac biomarkers in cardiac and non-cardiac surgical settings and provide an increasing evidence of their interest, validating different hierarchical steps which are mandatory before recommending a wide use of biomarkers for routine practice. Even if the first studies demonstrating an additional prognostic value of serum postoperative cTnI and/or preoperative BNP when compared with clinical predictive models are now available, we still lack data concerning an actual positive impact of new biomarkers measurements on clinical decision making or practice, as well as patient care and outcome.

CONCLUSIONS

While use of new cardiac biomarkers in the perioperative period appears to be a simple and objective tool for risk stratification at the bedside, we still need to remain cautious concerning their additional clinical value on existing predictive models for routine practice.

Postoperative atrial fibrillation predicts long-term survival after aortic-valve surgery but not after mitral-valve surgery: a retrospective study

Background Postoperative atrial fibrillation (POAF) has been reported to be associated with reduced long-term survival after isolated coronary artery bypass grafting surgery. The objective of this study was to determine the impact of POAF on long-term survival after valvular surgery. Methods The authors retrospectively analysed the preoperative and operative data of 2986 consecutive patients with no preoperative history of atrial fibrillation undergoing first valvular surgery (aortic-valve replacement (AVR), mitral valve replacement or mitral valve repair (MVR/MVRp) with or without coronary artery bypass grafting surgery) in their institution between 1995 and 2008 (median follow-up 5.31 years, range 0.1-15.0). The authors investigated the impact of POAF on survival using multivariable Cox regression. Results Patients with POAF were older, and were more likely to have hypertension or renal failure when compared with patients without POAF. The 12-year survival in patients with POAF was 45.7±2.8% versus 61.4±2.1% in patients without POAF (p<0.001). On a multivariable analysis, when adjusting for age and other potential confounding factors, POAF tended to be associated with lower long-term survival (HR for all-cause death (HR)=1.17, 95% CI 1.00 to 1.38, p=0.051). The authors also analysed this association separately in patients with AVR and those with MVR/MVRp. In the multivariable analysis, POAF was a significant predictor of higher long-term mortality in patients with AVR (HR=1.22, CI 1.02 to 1.45, p=0.03) but not in patients with MVR/MVRp (HR=0.87, CI 0.58 to 1.29, p=0.48). Conclusions POAF is significantly associated with long-term mortality following AVR but not after MVR/MVRp. The underlying factors involved in the pathogenesis of POAF after MVR/MVRp may partially account for the lack of association between POAF and survival in these patients.

Inflammatory cytokines and atrial fibrillation: current and prospective views

Atrial fibrillation (AF) is the most common sustained arrhythmia and a challenging clinical problem encountered in daily clinical practice. There is an increasing body of evidence linking inflammation to a broad spectrum of cardiovascular conditions including AF. Historical evidence supports an association between AF and inflammation and is consistent with the association of AF with inflammatory conditions of the heart, such as myocarditis and pericarditis. AF has been associated with myocardial oxidative stress, and antioxidant agents have demonstrated antiarrhythmic benefit in humans. Increased plasma interleukin (IL)-6, C-reactive protein (CRP), and plasma viscosity support the existence of an inflammatory state among "typical" populations with chronic AF. These indexes of inflammation are related to the prothrombotic state and may be linked to the clinical characteristics of the patients (underlying vascular disease and comorbidities), rather than simply to the presence of AF itself. It has been suggested that inflammation may have a role in the development of atrial arrhythmias after cardiac surgery, and that a genetic predisposition to develop postoperative complications exists. Cytokines can have a prognostic significance; IL-6 levels, CRP, and other cytokines may have prognostic value in AF. Cytokine lowering therapies, statins, angiotensin converting enzyme inhibitors and other anti-inflammatory agents may have a role in the treatment of AF. The present article provides an overview of the evidence linking inflammatory cytokines to AF and their therapeutic and prognostic implications.

Preoperative angiotensin-blocking drug therapy is not associated with atrial fibrillation after cardiac surgery

BACKGROUND

Preoperative use of angiotensin-blocking drug therapy (ABDT) with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers and its link to occurrence of postoperative atrial fibrillation (POAF), a common marker of poor outcomes after cardiac surgery, remain controversial.

METHODS

From 1997 to 2003, 10,552 patients underwent coronary artery bypass grafting with or without valve surgery. To adjust for differences of clinical characteristics between patients who received ABDT within 24 hours before surgery compared with those who did not, propensity score analyses were conducted.

RESULTS

Angiotensin-blocking drug therapy was prescribed in 4,795 (45%) before surgery, of which 1,725 (36%) developed POAF before discharge versus 1,908 (33%) of 5,757 patients who did not receive ABDT (unadjusted odds ratio 1.13, 95% CI 1.05-1.25, P < .01). In 6,744 propensity score-matched patients with well-balanced comorbidity profiles, ABDT was not associated with POAF (odds ratio 1.05, CI 0.95-1.16, P = .38). Stratified analysis within quintiles of propensity score and propensity-adjusted logistic multivariable regression confirmed these findings.

CONCLUSIONS

In this large observational study, we found no evidence of an association between preoperative angiotensin blockade and the occurrence of POAF. Adequately powered randomized studies are needed to clarify the best strategy of perioperative ABDT in patients with and without guideline-based indications.

Systemic vascular cell adhesion molecule-1 predicts the occurrence of post-operative atrial fibrillation

BACKGROUND

Post-operative atrial fibrillation occurs in 30% of patients after on-pump heart surgery and is associated to elevated inflammatory markers. We have evaluated if the systemic biomarkers of inflammation and endothelial damage, vascular cell adhesion molecule-1 (VCAM-1) and soluble thrombomodulin may help in identifying patients prone to development of post-operative atrial fibrillation.

METHODS

One hundred and forty-four patients in sinus rhythm submitted to elective coronary artery bypass surgery. Systemic inflammatory, oxidative stress and endothelial damage markers were measured at baseline and 72 h after surgery. During the procedure, a sample of the right atrial appendage was obtained for histochemistry. Electrocardiogram was monitored for 72 h after surgery for event adjudication.

RESULTS

22% of the patients developed post-operative atrial fibrillation. Baseline systemic inflammatory markers did not differ between patients with or without post-operative atrial fibrillation. However, baseline plasma VCAM-1 and thrombomodulin levels were significantly higher in patients who developed post-operative atrial fibrillation. After adjustment for age, gender, comorbidities and concurrent medication, circulating VCAM-1 remained as an independent predictor for post-operative atrial fibrillation development. No association was observed between systemic plasma VCAM-1 and VCAM-1 tissue expression in the right atrial appendage.

CONCLUSIONS

In patients undergoing coronary artery bypass surgery, elevated VCAM-1 levels predict a higher risk for post-operative atrial fibrillation. Plasma VCAM-1 elevation is not related to its expression in the right atria, suggesting that systemic endothelial damage rather than local changes pre-exist in patients who develop the arrhythmia.

Usefulness of neutrophil/lymphocyte ratio as predictor of new-onset atrial fibrillation after coronary artery bypass grafting

The neutrophil/lymphocyte (N/L) ratio integrates information on the inflammatory milieu and physiologic stress. It is an emerging marker of prognosis in patients with cardiovascular disease. We investigated the relation between the N/L ratio and postoperative atrial fibrillation (AF) in patients undergoing coronary artery bypass grafting. In a prospective cohort study, 275 patients undergoing nonemergency coronary artery bypass grafting were recruited. Patients with previous atrial arrhythmia or requiring concomitant valve surgery were excluded. The N/L ratio was determined preoperatively and on postoperative day 2. The study end point was AF lasting >30 seconds. Patients who developed AF (n = 107, 39%) had had a greater preoperative N/L ratio (median 3.0 vs 2.4, p = 0.001), but no differences were found in the other white blood cell parameters or C-reactive protein. The postoperative N/L ratio was greater in patients with AF (day 2, median 9.2 vs 7.2, p <0.001), and in multivariate models, a greater postoperative N/L ratio was independently associated with a greater incidence of AF (odds ratio 1.10 per unit increase, p = 0.003: odds ratio for N/L ratio >10.14 [optimal postoperative cutoff in our cohort], 2.83 per unit, p <0.001). Elevated pre- and postoperative N/L ratios were associated with an increased occurrence of AF after coronary artery bypass grafting. In conclusion, these results support an inflammatory etiology in postoperative AF but suggest that other factors are also important.

Does treatment with n-3 polyunsaturated fatty acids prevent atrial fibrillation after open heart surgery?

AIMS

To examine the effect of n-3 polyunsaturated fatty acid (PUFA) treatment on the incidence of post-operative atrial fibrillation (POAF).

METHODS AND RESULTS

A prospective, randomized, double-blinded, placebo-controlled trial was conducted in patients admitted for coronary artery bypass grafting and/or valvular repair surgery. The patients received either n-3 PUFA capsules, containing a daily dose of 1240 mg eicosapentaenoic acid and 1000 mg docosahexaenoic acid, or olive oil capsules for 5-7 days prior to surgery and post-operatively until hospital discharge. The endpoint was POAF, defined as an episode detected by continuous electrocardiographic monitoring, lasting >5 min. A total of 170 patients were enrolled in the study, and 168 patients underwent surgery. Their median age was 67 (range 43-82) years, and 79.2% were males. There was no difference in baseline characteristics between the n-3 PUFA group (n = 83) and the placebo group (n = 85), and the incidence of POAF was 54.2 and 54.1% (P = 0.99), respectively. Factors associated with POAF included advanced age, peak post-operative C-reactive protein level, valvular surgery, lower body mass index, and non-smoking, but n-3 PUFA concentration in plasma lipids was not associated with POAF.

CONCLUSION

There is no evidence for a beneficial effect of treatment with n-3 PUFA on the occurrence of POAF in patients undergoing open heart surgery.