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PoAF is the most common complication after cardiac surgery and may occur in patients with pre-existing arrhythmogenic substrate. Characterization of this substrate could aid in identifying patients at risk for PoAF. We therefore compared intra-atrial conduction parameters and electrogram morphology between patients without and with early- (≤5 days after surgery) and late- (up to 5 years) postoperative atrial fibrillation (PoAF). Epicardial mapping of the right and left atrium and Bachmann's Bundle (BB) was performed during sinus rhythm (SR) in 263 patients (207male, 67 ± 11 years). Unipolar potentials were classified as single, short or long double and fractionated potentials. Unipolar voltage, fractionation delay (time difference between the first and last deflection), conduction velocity (CV) and conduction block (CB) prevalence were measured. Comparing patients without (N = 166) and with PoAF (N = 97), PoAF was associated with lower CV and more CB at BB. Unipolar voltages were lower and more low-voltage areas were found at the left and right atrium and BB in PoAF patients. These differences were more pronounced in patients with late-PoAF (6%), which could even occur up to 5 years after surgery. Although several electrophysiological parameters were related to PoAF, age was the only independent predictor. Patients with de novo PoAF have more extensive arrhythmogenic substrate prior to cardiac surgery compared to those who remained in SR, which is even more pronounced in late-PoAF patients. Future studies should evaluate whether intra-operative electrophysiological examination enables identification of patients at risk for developing PoAF and hence (preventive) therapy. [Display omitted] • PoAF is associated with pre-existing substrate, consisting of conduction slowing, lower unipolar voltages and more LVAs. • Patients with late-PoAF have even more pronounced arrhtyhmogenic substrates prior to cardiac surgery. • This substrate is particularly located at Bachmann's Bundle, although clear differences in electrophysiological parameters are also present at the left and right atrium. • The first episode of late-PoAF could even occur up to 5 years after surgery and occurred only in patients who also developed early-PoAF. [ABSTRACT FROM AUTHOR]

Changes in cardiac autonomic regulation and P-wave characteristics are associated with the occurrence of atrial fibrillation. The purpose of this study was to evaluate whether combined preoperative non-invasive determination of cardiac autonomic regulation and PR interval allows for the identification of patients at risk of new-onset atrial fibrillation after cardiac surgery. RR, PR and QT intervals, and linear and non-linear heart rate variability parameters from 20 min high-resolution electrocardiographic recordings were determined one day before surgery in 150 patients on chronic beta blockers undergoing elective coronary artery bypass grafting, aortic valve replacement, or both, electively. Thirty-one patients (21%) developed postoperative atrial fibrillation. In the atrial fibrillation group, more arterial hypertension, a greater age, a higher EuroSCORE II, a higher heart rate variability index (pNN50: 9 ± 20 vs. 4 ± 10, p = 0.050), a short PR interval (156 ± 23 vs. 173 ± 31 ms; p = 0.011), and a reduced short-term scaling exponent of the detrended fluctuation analysis (DFA1, 0.96 ± 0.36 vs. 1.11 ± 0.30 ms; p = 0.032) were found compared to the sinus rhythm group. Logistic regression modeling confirmed PR interval, DFA1 and age as the strongest preoperative predictors of postoperative atrial fibrillation (area under the receiver operating characteristic curve = 0.804). Patients developing atrial fibrillation after cardiac surgery presented with severe cardiac autonomic derangement and a short PR interval preoperatively. The observed state characterizes both altered heart rate regulation and arrhythmic substrate and is strongly related to an increased risk of postoperative atrial fibrillation. • Cardiac autonomic derangement predisposes to postoperative atrial fibrillation. • Observed autonomic changes are mirrored in non-linear heart rate variability DFA1. • Parasympathetic coactivation not withdrawal closest reflects the mode of derangement. • Shorter PR interval further increases risk of postoperative atrial fibrillation. • Prediction model including age, PR interval and DFA1 yielded AUC of 0.804. [ABSTRACT FROM AUTHOR]

Introduction Post-operative atrial fibrillation (POAF) is one of the most common complications following cardiac surgery. However, it is unclear whether there is a relationship between obesity and POAF. We thus assessed all available evidence investigating the association between obesity and POAF, also considering any link between POAF and other post-operative conditions such as mortality, stroke, myocardial infarctions and respiratory complications. Methods Five electronic databases were searched and relevant studies were identified. Data was extracted and meta-analyzed from the identified studies. Results We found that obese patients had significantly higher odds of POAF when compared with non-obese patients (P = 0.006). There was also significant heterogeneity among the identified studies. POAF when compared with no-POAF was associated with an increased risk of stroke (P < 0.0001), 30-day mortality (P = 0.005) and respiratory complications (P < 0.00001). However, we found no significant link between POAF and myocardial infarctions (P = 0.79). Conclusions Our findings suggest that obesity is associated with a moderately higher risk of POAF. While POAF is also associated with an increased incidence of stroke, 30-day mortality and respiratory complications, further studies must be conducted before conclusions can be made about the long-term outcomes. [ABSTRACT FROM AUTHOR]

Background Posterior pericardiotomy (PP) has been shown to be effective in patients after cardiac surgery complicated by a reduced the incidence of atrial fibrillation (AF). However, the role of PP in patients following coronary artery bypass graft (CABG) remains ambiguous. We aimed to systematically evaluate the efficacy of PP in preventing postoperative AF in adult patients after CABG. Methods Studies were identified by searching multiple electronic databases (PubMed, Embase, and the Cochrane Library) through February, 2016, and by reviewing reference lists of obtained articles. The outcome measure was the incidence of postoperative AF. The meta-analysis was performed with the fixed-effect model or random-effect model according to heterogeneity. Results Ten randomized trials incorporating 1648 patients were included in this meta-analysis (822 in the PP group and 826 in the control group). The cumulative incidence of AF was 10.6% in the PP group and 24.9% in the control group. Meta-analysis with all studies using a random-effects model suggested that PP had significant effect on the prevention of postoperative AF ( I 2 55%; P < 0.00001; OR, 0.36; 95% CI, 0.23–0.56; RR, 0.45; 95% CI, 0.31–0.64). Sensitivity analyses by methodological quality and surgical technique yields similar results. Conclusions This meta-analysis indicates that PP shows beneficial efficacy in preventing postoperative AF in adult patients after CABG. This finding encourages the use of PP to prevent postoperative AF after CABG, but, more high quality randomized controlled trials are still warranted to confirm the safety. [ABSTRACT FROM AUTHOR]

Background Postoperative atrial fibrillation (AF) is a common complication after cardiac surgery. Inflammation is believed to play a pivotal role in the etiology of postoperative AF. There is a suggestion from small studies that perioperative treatment with corticosteroids may reduce postoperative AF. The DExamethasone for Cardiac Surgery (DECS) study was a large randomized trial showing no protective effect of dexamethasone on major adverse events. The aim of this study was to investigate the effect of dexamethasone treatment on the occurrence of AF after cardiac surgery. Methods The DECS study compared intra-operative dexamethasone (1 mg/kg) or placebo treatment in 4494 adult patients undergoing cardiac surgery. AF was defined by the occurrence of any reported AF within 30 days after surgery. We also performed an in-depth analysis of a subset of 1565 patients on new-onset AF. Relative risks (RRs) with 95% confidence intervals (CIs) were calculated. Results The incidence of any AF in the main study of 4494 patients was 33.1% in the dexamethasone and 35.2% in the placebo group (RR 0.94, 95% CI: 0.87-1.02, p = 0.14). In the substudy of 1565 patients, the incidence of new-onset AF was 33.0% vs. 35.5% (RR 0.93, 95% CI: 0.81-1.07, p = 0.31), respectively. There was no protective effect of dexamethasone across clinically important patient subgroups. Conclusion Intraoperative administration of dexamethasone had no protective effect on the occurrence of any or new-onset atrial fibrillation after cardiac surgery. Therefore, the use of dexamethasone for the reduction of postoperative AF should not be recommended. [ABSTRACT FROM AUTHOR]

Abstract: Oxidative stress has been strongly involved in the underlying mechanism of atrial fibrillation, particularly in the arrhythmia occurring in patients undergoing cardiac surgery with extracorporeal circulation (postoperative atrial fibrillation). The ischemia/reperfusion injury thus occurring in the myocardial tissue contributes to the development of tissue remodeling, thought to be responsible for the functional heart impairment. Consequently, structural changes due to the cardiac tissue biomolecules attack by reactive oxygen and/or nitrogen species could account for functional changes in ion channels, transporters, membrane conductance, cytosolic transduction signals, and other events, all associated with the occurrence of arrhythmic consequences. The lack of success and significant side effects of anti-arrhythmic drugs have given rise to attempts aimed to develop alternative novel pharmacologic treatments. On this line, the biological properties of the antioxidant vitamins C and E suggest that they could decrease the vulnerability of the heart to the oxidative damage. Nevertheless, very few studies to assess their anti-arrhythmic effects have been reported in humans. The clinical and experimental evidence supporting the view that the pharmacological use of antioxidant vitamins could contribute to prevent postoperative atrial fibrillation is presented. [Copyright &y& Elsevier]

Abstract: Although all beta blockers appear to be effective in the prevention of postoperative atrial fibrillation (AF) following coronary artery bypass surgery (CABG), carvedilol was found to be much more effective than metoprolol in this respect as the current study clearly delineated. We believe that the ongoing COMPACT trial will answer the question of whether or not carvedilol is more superior than metoprolol to prevent postoperative AF in patients undergoing CABG. [Copyright &y& Elsevier]

Abstract: Atrial fibrillation is the most common sustained arrhythmia encountered following cardiac surgery. Although anti-arrhythmic drugs such as beta-blockers and amiodarone are recommended and used in clinical practice, the incidence of postoperative atrial fibrillation (POAF) is still very high. Recent evidence suggests oxidative stress may play an important role in the pathogenesis and perpetuation of POAF. Increased reactive oxygen species and activated atrial nicotinamide adenine dinucleotide phosphate (NADPH) oxidases after cardiac surgery are key targets for the prevention of POAF. In addition to statins, Vitamin C and E, N-acetylcysteine and carvedilol, some other anti-oxidant interventions such as thiazolidinediones, nitric oxide donor or precursor, probucol, levosimendan and NADPH oxidase inhibitors have emerged as novel strategies in the prevention of POAF. [ABSTRACT FROM AUTHOR]