Risk Factors for Postoperative Atrial Fibrillation in Myocardial Revascularization Surgery: A 15-Year Experience.

Background: Myocardial revascularization surgery (MRV) is a revascularization therapy for coronary artery disease aimed at improving survival conditions. Elderly patients with increased comorbidities undergoing MRV face challenges in preventing postoperative complications, including atrial fibrillation (AF), a common arrhythmia occurring in 40% of cases or even in 80% of cases if the procedure is combined with valve surgery. This study aimed to determine the risk factors associated with the appearance of postoperative AF (POAF) in patients undergoing isolated MRV. Methods: This is an epidemiological, retrospective, and analytical case-control study (90 cases and 360 controls). Results: Mortality within the group of patients who presented with POAF in the study population was 15.5%, and 9.44% in the control group. Logistic regression showed an association of AF with the presurgical variables age >60 years and urgent/emergency surgery and the postsurgical variables cardiogenic shock, blood transfusion, pulmonary edema, pleural effusion, orotracheal reintubation, and mechanical ventilation time. Conclusions: Strategies should be proposed for the timely identification of risk factors and postoperative complications related to AF onset to avoid the increased morbidity and mortality associated with this type of arrhythmia during the postoperative period.

Rivaroxaban versus warfarin in postoperative atrial fibrillation: Cost-effectiveness analysis in a single-center, randomized, and prospective trial.

Objectives: Postoperative atrial fibrillation is the most common clinical complication after coronary artery bypass graft surgery. It is associated with a high risk of both stroke and death and increases the length of hospital stay and costs. This study aimed to evaluate anticoagulants in postoperative atrial fibrillation. Methods: A single-center, randomized, prospective, and open-label study. The trial was conducted in Heart Institute at University of São Paulo, Brazil. Patients who developed postoperative atrial fibrillation were randomized to anticoagulation with rivaroxaban or warfarin plus enoxaparin bridging. The primary objective was the cost-effectiveness evaluated by quality-adjusted life years, using the SF-6D questionnaire. The secondary end point was the combination of death, stroke, myocardial infarction, thromboembolic events, infections, bleeding, readmissions, and surgical reinterventions. The safety end point was any bleeding using the International Society on Thrombosis and Haemostasis score. Follow-up period was 30 days after hospital discharge. Results: We analyzed 324 patients and 53 patients were randomized. The median cost-effectiveness was $1423.20 in the warfarin group versus $586.80 in the rivaroxaban group (P = .002). The median cost was lower in the rivaroxaban group, $450.20 versus $947.30 (P < .001). The secondary outcome was similar in both groups, 44.4% in warfarin group versus 38.5% in the rivaroxaban group (P = .65). Bleeding occured in 25.9% in the warfarin group versus 11.5% in the rivaroxaban group (P = .18). Conclusions: Rivaroxaban was more cost-effective when compared with warfarin associated with enoxaparin bridging in postoperative atrial fibrillation after isolated coronary artery bypass grafting.

Novel Combined Antioxidant Strategy against Hypertension, Acute Myocardial Infarction and Postoperative Atrial Fibrillation.

Reactive oxygen species (ROS) play a physiological role in the modulation of several functions of the vascular wall; however, increased ROS have detrimental effects. Hence, oxidative stress has pathophysiological impacts on the control of the vascular tone and cardiac functions. Recent experimental studies reported the involvement of increased ROS in the mechanism of hypertension, as this disorder associates with increased production of pro-oxidants and decreased bioavailability of antioxidants. In addition, increased ROS exposure is found in ischemia-reperfusion, occurring in acute myocardial infarction and cardiac surgery with extracorporeal circulation, among other settings. Although these effects cause major heart damage, at present, there is no available treatment. Therefore, it should be expected that antioxidants counteract the oxidative processes, thereby being suitable against cardiovascular disease. Nevertheless, although numerous experimental studies agree with this notion, interventional trials have provided mixed results. A better knowledge of ROS modulation and their specific interaction with the molecular targets should contribute to the development of novel multitarget antioxidant effective therapeutic strategies. The complex multifactorial nature of hypertension, acute myocardial infarction, and postoperative atrial fibrillation needs a multitarget antioxidant strategy, which may give rise to additive or synergic protective effects to achieve optimal cardioprotection.

Occurrence of recently diagnosed atrial fibrillation in the immediate postoperative period of myocardial revascularization surgery. Although common, a devalued complication

SUMMARY Atrial fibrillation (AF) is the most common arrhythmia in the postoperative period of cardiac surgery, with a prevalence between 15-40% after coronary artery bypass surgery (CABG). Several strategies have been tested for the prevention and management of AF postoperatively. Previous studies and analysis of records have shown higher rates of hospitalization and clinical outcomes associated with this entity, including increased mortality in the short- and long-term. This perspective reviews the topic, and offers recommendations for the management of this arrhythmia in the postoperative period of CABG, with a special focus on anticoagulation strategies.

Predicting postoperative atrial fibrillation after myocardial revascularization without cardiopulmonary bypass: A retrospective cohort study.

INTRODUCTION: Considering the threat imposed by postoperative atrial fibrillation (POAF) after coronary artery bypass grafting (CABG) and the potential benefits of off-pump CABG, the objective of this study was to describe the incidence and identify predictor factors for POAF in patients undergoing CABG without cardiopulmonary bypass (CPB). METHODS: In this retrospective cohort study, we enrolled patients undergoing CABG without CPB between December 2008 and December 2011. The independent variables evaluated in this study were major patients' characteristics (age, sex, and ethnia), associated comorbidities (systemic arterial hypertension, diabetes mellitus, thyroid dysfunction, chronic renal failure (CRF), chronic obstructive pulmonary disease, and ischemic stroke), and the revascularization approach (the number of grafts used, the revascularized branch, and the choice of vascular graft (arterial or venous). The dependent variable was the onset of atrial fibrillation after the procedure. RESULTS: Two hundred and eighty patients were included in the present study. The overall incidence of POAF after off-pump CABG was 5.0%. In the univariate analysis, the presence of chronic renal failure (odds ratio [OR], 3.01 [1.00-9.06], P = .049) and the use of venous-origin graft alone (OR, 9.67 [1.15-81.56], P = .037) were associated with an increased risk or POAF. These findings were confirmed after multivariate analysis, for both CRF (OR, 3.31 [1.05-10.46], P = .042) and the use of venous-origin graft alone (OR, 9.81 [1.13-85.35], P = .039). CONCLUSION: Off-pump coronary artery bypass grafting proved a safe and effective procedure, with low postoperative atrial fibrillation occurrence, for myocardial revascularization. Chronic renal insufficiency and the use of venous-origin graft solely proved to be independent predictor factors for PAOF.

[Bayes' syndrome in cardiac surgery: prevalence of interatrial block in patients younger than 65 years undergoing cardiac surgery and association with postoperative atrial fibrillation]. / Síndrome de Bayés en cirugía cardiaca: prevalencia de bloqueo interauricular en menores de 65 años sometidos a cirugía cardiaca y su asociación con fibrilación auricular en el postoperatorio.

OBJECTIVE: Interatrial block (IAB) is a well-known entity that is associated with an increased risk of atrial fibrillation (AF). This association is called Bayes' syndrome. The aim of our study was to define the prevalence of IAB among patients younger than 65 years undergoing cardiac surgery and determine whether there is an association between the presence of interatrial conduction delay and postoperative atrial fibrillation (POAF). METHOD: A total of 207 patients were enrolled. Partial IAB was defined as P-wave>120ms. Advanced IAB was defined as P-wave>120ms+biphasic morphology in the inferior leads. Ocurrence of POAF was assessed and a comparative analysis was conducted between patients that did and did not develop AF. RESULTS: IAB prevalence was 78.3% (partial 66.2%, advanced 12.1%). POAF occurred in 28.5% of all patients, and was more frequent among patients with advanced IAB (44%) compared to 27.7% and 24.4% of POAF among patients with partial IAB and without IAB, respectively. Patients who developed POAF were significantly older, had significantly higher NTproBNP, higher prevalence of atrial enlargement and thyroid disease. After multivariate analysis, advanced IAB was found to be independently associated with POAF. CONCLUSIONS: IAB is a frequent finding among patients undergoing cardiac surgery. According to our results, advanced IAB is independently associated with POAF in younger patients (<65 years) undergoing cardiac surgery.

Síndrome de Bayés en cirugía cardiaca: prevalencia de bloqueo interauricular en menores de 65 años sometidos a cirugía cardiaca y su asociación con fibrilación auricular en el postoperatorio / Bayes' syndrome in cardiac surgery: prevalence of interatrial block in patients younger than 65 years undergoing cardiac surgery and association with postoperative atrial fibrillation

Resumen Objetivo: El bloqueo interauricular (BIA) es una entidad asociada con un mayor riesgo de presentar fibrilación auricular (FA), constituyendo el denominado síndrome de Bayés. El objetivo de nuestro estudio fue definir la prevalencia de BIA en pacientes menores de 65 años sometidos a cirugía cardiaca y determinar si existe una asociación entre la presencia de BIA y la aparición de FA postoperatoria. Método: Se incluyeron un total de 207 pacientes. Se definió BIA parcial como onda P > 120 ms. Se definió BIA avanzado como onda P > 120 ms con morfología bifásica en derivaciones inferiores. Se determinó la frecuencia de aparición de FA postoperatoria y se realizó un análisis comparativo entre los pacientes que presentaron y los que no presentaron esta arritmia. Resultados: La prevalencia de BIA fue del 78.3% (parcial, 66.2%; avanzado, 12.1%). La frecuencia de aparición de FA fue del 28.5% de forma global, siendo mayor en los pacientes con BIA avanzado (44%) comparado con pacientes con BIA parcial (27.7%) y sin BIA (24.4%). Los pacientes que presentaron FA fueron significativamente mayores, con niveles más elevados de NTproBNP y presentaron mayor prevalencia de dilatación auricular y de patología tiroidea. El análisis multivariable demostró una asociación independiente entre BIA avanzado y FA postoperatoria. Conclusiones: El BIA es una entidad frecuente en pacientes sometidos a cirugía cardiaca. En nuestro estudio, el BIA avanzado se asocia de forma independiente con una mayor frecuencia de FA postoperatoria en pacientes menores de 65 años sometidos a cirugía cardiaca.

Abstract Objective: Interatrial block (IAB) is a well-known entity that is associated with an increased risk of atrial fibrillation (AF). This association is called Bayes' syndrome. The aim of our study was to define the prevalence of IAB among patients younger than 65 years undergoing cardiac surgery and determine whether there is an association between the presence of interatrial conduction delay and postoperative atrial fibrillation (POAF). Method: A total of 207 patients were enrolled. Partial IAB was defined as P-wave > 120 ms. Advanced IAB was defined as P-wave > 120 ms + biphasic morphology in the inferior leads. Ocurrence of POAF was assessed and a comparative analysis was conducted between patients that did and did not develop AF. Results: IAB prevalence was 78.3% (partial 66.2%, advanced 12.1%). POAF occurred in 28.5% of all patients, and was more frequent among patients with advanced IAB (44%) compared to 27.7% and 24.4% of POAF among patients with partial IAB and without IAB, respectively. Patients who developed POAF were significantly older, had significantly higher NTproBNP, higher prevalence of atrial enlargement and thyroid disease. After multivariate analysis, advanced IAB was found to be independently associated with POAF. Conclusions: IAB is a frequent finding among patients undergoing cardiac surgery. According to our results, advanced IAB is independently associated with POAF in younger patients (< 65 years) undergoing cardiac surgery.

Analysis of Circulating miR-1, miR-23a, and miR-26a in Atrial Fibrillation Patients Undergoing Coronary Bypass Artery Grafting Surgery.

Atrial fibrillation (AF) is the most common arrhythmia after cardiac surgery. From a pathophysiological point of view, a myriad of factors such as trauma, atrial dilation, ischemia, mechanical myopericarditis, autonomic imbalance, loss of connexins, AF nest remodeling, inflammation, sutures, and dysfunction caused by postextracorporeal circulation can contribute to postoperative atrial fibrillation (POAF) resulting in a longer hospital stay and consequently higher cost. Recent studies showed that short fragments of RNA, called microRNA (miRNA), can contribute to the development of several cardiovascular diseases, including AF. The aim of this study was to evaluate the levels of circulating miRNAs (miR-1, -23a, and -26a) that can be involved in POAF. Patients submitted to coronary artery bypass graft surgery were grouped in POAF (24 patients) and without POAF (24 patients). Results showed older age, longer clamp-time, and more days in the intensive care unit as well as a longer total hospital stay in the POAF group. Preoperative levels of circulating miRNAs were similar. Analysis of miRNAs revealed significantly lower circulating levels of miRNA-23a (P = 0.02) and -26a (P = 0.01) in the POAF group during the postoperative period. Receiver operating characteristic (ROC) analysis showed the area under the ROC curve of miR-23a and miR-26a for predicting FA was 0.63 (95% confidence interval [CI]: 0.51-0.74; P = 0.02) and 0.66 (95% CI: 0.55-0.77; P = 0.01), respectively. Our data suggests that circulating miRNA-23a and -26a may be involved in the underlying biology of postoperative AF development.

The effects of polyunsaturated fatty acids and antioxidant vitamins on atrial oxidative stress, nitrotyrosine residues, and connexins following extracorporeal circulation in patients undergoing cardiac surgery.

Cardiac surgery with extracorporeal circulation is characterized by different degrees of myocardial ischemia/reperfusion, which is often associated with postoperative atrial fibrillation (POAF). We have previously shown that a novel preventive therapy based on the reinforcement of the antioxidant system using omega-3 fatty acids plus antioxidant vitamin supplementation applied to patients undergoing cardiac surgery reduces POAF occurrence. We hypothesized that oxidative stress and nitrosative stress are involved in the development of an arrhythmogenic substrate by their effect on connexins (Cx40, Cx43 and Cx45) abundance and distribution pattern. Therefore, we have assessed the effect of redox status on atrial tissue in patients undergoing cardiac surgery. Placebo/POAF and supplemented/POAF patients showed 276 and 170% higher reactive oxygen species (ROS) levels and 223 and 96% higher nitrotyrosine residues levels, respectively, compared to sinus rhythm (SR). In POAF tissue, antioxidant supplementation prevented Cx40 and Cx43 lateralization on cardiomyocyte sarcolemma, keeping them at the intercalated disks. POAF samples showed Cx40 heterogeneous distribution pattern, presenting tissue areas lacking this protein (49 and 55% lower levels in placebo/POAF and supplemented/POAF groups, respectively, compared to SR). Of note, Cx45 overexpression occurred in POAF, being 211 and 167% higher in placebo/POAF and supplemented/POAF groups, respectively, compared to SR. It is concluded that treatment with omega-3 fatty acids and antioxidant vitamins reduces oxidative and nitrosative stress and prevents Cx40/Cx43 lateralization in atrial tissue likely contributing to POAF prevention. However, it failed to fully prevent POAF occurrence because these compounds have no effects on the normalization of Cx40 down-regulation and Cx45 up-regulation, which may promote POAF.

Association between obesity and postoperative atrial fibrillation in patients undergoing cardiac operations: a systematic review and meta-analysis.

In a systematic review and random-effects meta-analysis, we evaluated whether obesity is associated with postoperative atrial fibrillation (POAF) in patients undergoing cardiac operations. We selected 18 observational studies until December 2011 that excluded patients with preoperative AF (n=36,147). Obese patients had a modest higher risk of POAF compared with nonobese (odds ratio, 1.12; 95% confidence interval, 1.04 to 1.21; p=0.002). The association between obesity and POAF did not vary substantially by type of cardiac operation, study design, or year of publication. POAF was significantly associated with a higher risk of stroke, respiratory failure, and operative death.

Prevention of postoperative atrial fibrillation: novel and safe strategy based on the modulation of the antioxidant system.

Postoperative atrial fibrillation (AF) is the most common arrhythmia following cardiac surgery with extracorporeal circulation. The pathogenesis of postoperative AF is multifactorial. Oxidative stress, caused by the unavoidable ischemia-reperfusion event occurring in this setting, is a major contributory factor. Reactive oxygen species (ROS)-derived effects could result in lipid peroxidation, protein carbonylation, or DNA oxidation of cardiac tissue, thus leading to functional and structural myocardial remodeling. The vulnerability of myocardial tissue to the oxidative challenge is also dependent on the activity of the antioxidant system. High ROS levels, overwhelming this system, should result in deleterious cellular effects, such as the induction of necrosis, apoptosis, or autophagy. Nevertheless, tissue exposure to low to moderate ROS levels could trigger a survival response with a trend to reinforce the antioxidant defense system. Administration of n-3 polyunsaturated fatty acids (PUFA), known to involve a moderate ROS production, is consistent with a diminished vulnerability to the development of postoperative AF. Accordingly, supplementation of n-3 PUFA successfully reduced the incidence of postoperative AF after coronary bypass grafting. This response is due to an up-regulation of antioxidant enzymes, as shown in experimental models. In turn, non-enzymatic antioxidant reinforcement through vitamin C administration prior to cardiac surgery has also reduced the postoperative AF incidence. Therefore, it should be expected that a mixed therapy result in an improvement of the cardioprotective effect by modulating both components of the antioxidant system. We present novel available evidence supporting the hypothesis of an effective prevention of postoperative AF including a two-step therapeutic strategy: n-3 PUFA followed by vitamin C supplementation to patients scheduled for cardiac surgery with extracorporeal circulation. The present study should encourage the design of clinical trials aimed to test the efficacy of this strategy to offer new therapeutic opportunities to patients challenged by ischemia-reperfusion events not solely in heart, but also in other organs such as kidney or liver in transplantation surgeries.

Proteína C reactiva de alta sensibilidad como predictor de fibrilación auricular postoperatoria / High-sensitivity C-reactive protein predicts postoperative atrial fibrillation

Introducción: La fibrilación auricular postoperatoria (FAPO) es una complicación frecuente en la cardiocirugía con circulación extracorpórea (CEC). El evento de isquemia-reperfusión secundario a la CEC produce inflamación como mediador de daño miocárdico causando FAPO. Objetivo: determinar el poder predictivo del marcador de inflamación proteína C reactiva de alta sensibilidad (hsCRP) en la FAPO. Hipótesis: la hsCRP predice la ocurrencia de FAPO. Material y Método: estudio observacional, analítico, incluyó 123 pacientes sometidos a cardiocirugía con CEC en el Hospital Clínico de la Universidad de Chile entre 2007 y 2010. El muestreo fue aleatorio simple de pacientes concurrentes a cirugía cardíaca. Se realizó monitoreo electrocardiográfico continuo y medición de hsCRP plasmática antes de la cirugía, 8 horas postoperatorias y al alta. Se realizó un análisis de regresión multivariada, considerando los factores de riesgo conocidos de FAPO, así como la hsCRP. Para variable cuantitativa continua, se realizó ANOVA-Bonferroni. Para análisis de Kaplan-Meier de cuartiles de hsCRP, se realizó test de tendencia log-rank. Se realizó una receiver operator curve (ROC) para determinar el poder predictivo de la hsCRP. Significancia: p<0,05. Resultados: Se describe el perfil clínico-epidemiológico de los pacientes. La hsCRP fue máxima a las 8 horas postoperatorias (ANOVA-Bonferroni p<0,01). El análisis de regresión multivariada relacionó significativamente hsCRP y ocurrencia de FAPO (p<0,01). A mayor cuartil de hsCRP se asoció mayor ocurrencia de FAPO (p<0,01). El área bajo la curva ROC fue 0,73. Discusión: La hsCRP postoperatoria constituye una valiosa herramienta predictora de ocurrencia de FAPO en el contexto de cirugía cardíaca con CEC.

Introduction: Postoperative atrial fibrillation (POAF) is a common complication of cardiac surgery with extracorporeal circulation. Is associated with increased morbidity and health costs. The ischemia-reperfusion event secondary to extracorporeal circulation leads to inflammation, causing myocardial damage. Objective: The aim of this study is to determine the predictive power of high sensitivity C-reactive protein (hsCRP) in POAF.Hypothesis: hsCPR predicts POAF occurrence. Material and Method: An observational, analytical study, included 123 patients undergoing cardiac surgery with extracorporeal circulation at Universidad de Chile’s Hospital, between 2007 and 2010. Continuous electrocardiographic monitoring was performed and plasma hsCPR measurement before surgery, 8 hours postoperatively and at discharge. We performed a multivariate regressionanalysis considering the known risk factors for POAF and the hsCRP. For continuous quantitative variable ANOVA-Bonferroni was used. Kaplan-Meier analysis of quartiles of hsPCR was usedand Mantel-Cox log-rank test for trend test. Receiver operator curve (ROC) was performed to determine the predictive power of the hsPCR. Significance: p<0.05. Results: We describe the clinical and epidemiological characteristics of patients undergoingcardiac surgery. The hsCPR was highest at 8 postoperative hours (ANOVA-Bonferroni p<0.01). The multivariate regression analysis significantly correlated with the occurrence of hsPCRand POAF (p<0.01). The higher quartile of hsCPR was associated with increased occurrence of POAF (p<0.01). The area under the ROC curve was 0.73. Discussion: The postoperative hsPCR isa valuable predictor of the occurrence of POAF in the context of cardiac surgery with extracorporeal circulation.