Higher Incidence Of Postoperative Atrial Fibrillation Research Articles

Risk Factors of Postoperative Atrial Fibrillation After Isolated Coronary Artery Bypass Grafting Surgery in the Recent 10 Years: Clinical Analysis of 6229 Patients.

Postoperative atrial fibrillation (POAF) is a common complication after coronary artery bypass grafting (CABG) that prolongs hospitalization and increases expenses. Perioperative risk factors may predict POAF. From March 2015 to January 2023, 6229 patients who underwent isolated CABG and were in sinus rhythm before CABG were included in this retrospective study. The preoperative and postoperative variants of patients were collected and analyzed by univariate analyses between the patients with and without POAF. Multivariate logistic regression analysis was then used to study the independent risk factors for POAF. The incidence of POAF in this group of patients was 30.94%. Univariate analyses demonstrated that age (p < 0.001), hypertension (p < 0.001), smoking (p < 0.05), cardiopulmonary bypass (CPB) time (p < 0.01), and ejection fraction (EF, p < 0.01) were the risk factors for POAF. Multivariate logistic regression analysis determined the independent risk factors associated with POAF were old age (odds ratio [OR] = 1.062, p = 0.000) and low EF (OR = 0.980; p = 0.008). In the current era, after isolated CABG surgery, there is still a quite high incidence of POAF (30.94% in this group of CABG patients). The main risk factors correlating to POAF include age, hypertension, smoking, CPB time, and EF. Among these factors, multivariate analysis identified old age and low EF as the independent risk factors associated with POAF. Particular care should be taken in the perioperative period for these patients in the prevention of POAF.

Abstract 16671: Supraventricular Ectopic Activity Predicts Postoperative Atrial Fibrillation, New-Onset Atrial Fibrillation, and Worse Survival in Hypertrophic Cardiomyopathy

Introduction: Supraventricular ectopic activity (SEA), in the form of frequent premature atrial contractions (PACs) and runs of PACs, has been considered a marker of foci that are capable of firing rapidly to initiate atrial fibrillation (AF), but the cut-off value has not been determined. Therefore, we aimed to examine the association between SEA and postoperative AF (POAF) and clinical outcomes and to investigate the cut-off value in patients with hypertrophic cardiomyopathy. Methods: This cohort included 1491 consecutively recruited patients, of which 530 were excluded for various reasons, leaving 961 patients for final analysis. All patients received 24-hour Holter ECG monitoring 2-5 days before surgery. Results: The mean age of the study population was 48.4 (SD,12.3) years and 397 patients (41.3%) were female. The incidence of POAF was 20.7% and increased with PACs severity. Multivariable logistic regression analysis showed that supraventricular tachycardia (SVT) was independently associated with higher incidence of POAF and the model including SVT had the largest area under the curve (AUC) [AUC=0.710] among all the multivariable models. Furthermore, Kaplan-Meier survival curves demonstrated that patients in the tertile 3 (upper tertile of the total numbers of PACs), PACs&gt;100, PACs &gt;200, ESVEA (top decile of PACs plus top decile length of short atrial runs), and ESVEA3 (PACs&gt;100 plus top decile length of short atrial runs) group had significantly higher cumulative rates of new-onset AF and composite endpoints compared to their counterparts. On multivariable Cox regression analysis, PACs&gt; 100, PACs&gt;200, ESVEA, and ESVEA3 were independent indicators for higher incidence of new-onset AF and composite endpoints. Among those multivariate models, PACs &gt;200 had the higher effect size for predicting new-onset AF [Hazard ratio (HR) 3.13, 95% confidence interval (CI) 1.74-5.62] and composite endpoints [HR =2.00, 95%CI 1.30-3.06]. Conclusions: The incidence of POAF was 20.7% increasing with the severity of the PACs burden. Moreover, among supraventricular arrhythmias, SVT was the best indicator for predicting POAF. Likewise, PACs&gt;200 may consider as the best candidate for predicting a higher incidence of new-onset AF and composite endpoints.

Molecular mechanisms of postoperative atrial fibrillation in patients with obstructive sleep apnea.

Obstructive sleep apnea (OSA) promotes atrial remodeling and fibrosis, providing a substrate for atrial fibrillation (AF). Herein, we investigate the pathophysiological mechanisms of AF in association with OSA in a cohort of cardiac surgery patients. A prospective study including patients undergoing cardiac surgery. Biomarkers reflective of AF pathophysiology (interleukin [IL-6], C-reactive protein [CRP], von Willebrand factor [vWF], N-terminal pro-brain natriuretic peptide [NT-proBNP], high-sensitivity Troponin T [hs-TnT], and Galectin-3 [Gal-3]) was assessed by functional or immunological assays. miRNAs involved in AF were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). Using atrial tissue samples, fibrosis was assessed by Masson's trichrome. Connexin 40 and 43 (Cx40; Cx43) were evaluated by immunolabeling. Fifty-six patients (15 with OSA and 41 non-OSA) were included in this hypothesis-generating pilot study. OSA group had a higher incidence of postoperative AF (POAF) (46.7% vs. 19.5%; p = .042), presented an increased risk of POAF (OR 3.61, 95% CI 1.01-12.92), and had significantly higher baseline levels of NT-proBNP (p = .044), vWF (p = .049), Gal-3 (p = .009), IL-6 (p = .002), and CRP (p = .003). This group presented lower levels of miR-21 and miR-208 (both p < .05). Also, lower Cx40 levels in POAF and/or OSA patients (50.0% vs. 81.8%, p = .033) were found. The presence of interstitial fibrosis (according to myocardial collagen by Masson's trichrome) was raised in OSA patients (86.7% vs. 53.7%, p = .024). Several biomarkers and miRNAs involved in inflammation and fibrosis were dysregulated in OSA patients, which together with a higher degree of interstitial fibrosis, altered miRNA, and Cxs expression predisposes to the development of a substrate that increases the AF risk.

Association of postoperative atrial fibrillation with higher dosing ratios of protamine-to-heparin.

Background: Postoperative atrial fibrillation (POAF) is defined as new-onset AF in the immediate postoperative period. The relatively high incidence of POAF after cardiac surgery is well described, but pathophysiological mechanisms underlying the initiation, maintenance, and progression of POAF may be multifactorial and have not yet been comprehensively characterized. One of the mechanisms includes altered Ca2+ kinetics. Accumulating evidence has suggested that altered atrial cytosolic calcium handling contributes to the development of POAF, protamine reversibly modulates the calcium release channel/ryanodine receptor 2 (RyR2) and voltage-dependent cardiac RyR2. However, it is currently unknown whether such abnormalities contribute to the arrhythmogenic substrate predisposing patients to the development of POAF. Methods: We have retrospectively analyzed 147 patients who underwent cardiac surgery with cardiopulmonary bypass support. Of these, 40 patients were excluded from the analysis because of pre-existing AF. All patients received heparin followed by protamine at different dosing ratios of protamine-to-heparin, depending on the periods studied. Results: The dosing ratio of protamine-to-heparin=1.0 was compared with higher dosing ratios of protamine-to-heparin >1.0 up to 1.7. POAF developed in 15 patients (15/107=14%), of these, 5 out of 57 patients (33.3%) in the dosing ratio of protamine-to-heparin=1.0 and 10 out of 35 patients (66.7%) in the higher dosing ratios of protamine-to-heparin. Statistical significance was observed in patients with higher dosing ratios of protamine-to-heparin, compared with the dosing ratio of protamine-to-heparin=1.0 (odds ratio=3.890, 95% CI=1.130-13.300, p-value=0.031). When types of diseases were analyzed in terms of higher dosing ratios of protamine-to-heparin, only valvular disorders were significantly associated with POAF (p=0.04). Conclusions: Protamine is clinically utilized to reverse heparin overdose and has been shown to display immunological and inflammatory alterations. However, its association with POAF has not been reported. Our results provide evidence that higher dosing ratios of protamine-to-heparin may increase the incidence of POAF.

New-Onset Sleep Disorders before Cardiac Surgery May Indicate an Increased Risk of Postoperative Atrial Fibrillation.

We aimed to determine if sleep disorders before cardiac surgery indicate an increased risk of postoperative atrial fibrillation (POAF). In this study, 238 patients undergoing coronary artery bypass grafting in our center were included. Patients were separated into the preoperative sleep disorder group and the control group. The primary endpoint was the incidence of POAF, and the secondary endpoints were the incidence of postoperative stroke, duration of invasive ventilation, length of intensive care unit, and hospitalization stay. Propensity score matching and multivariable logistic regression were used for adjusting potential confounders. A total of 165 (69.3%) patients had sleep disorders before surgery, and 73 well-matched pairs were generated. A higher incidence of POAF was found in the preoperative sleep disorder group (16.4% versus 5.5%, p = 0.034). In multivariable logistic regression, preoperative sleep disorders were correlated to a higher risk of POAF (odds ratio = 4.627, 95% confidence interval: 1.181-18.123, p = 0.028). In the subgroup of patients without long-term sleep disorders, those who experienced preoperative sleep disorders had a higher incidence of POAF (16.1% versus 4.3%, p = 0.024), meanwhile, no difference was found in the subgroup of long-term sleep disorders. New-onset sleep disorders before cardiac surgery may indicate a higher incidence of POAF.

Radiofrequency pulmonary vein isolation for the prevention of new-onset atrial fibrillation after coronary artery bypass grafting

Aim. To evaluate the in-hospital results of the epicardial bipolar radiofrequency ablation of the pulmonary vein in the prevention of new-onset postoperative atrial fibrillation (POAF) in coronary artery disease (CAD) patients undergoing coronary artery bypass graft (CABG) surgery in a pilot randomised multi-centre controlled Pulmonary Vein Ablation (PULVAB).Methods. The pilot study was conducted for the organisation of a multi-centre randomised PULVAB trial. We enrolled 63 CAD patients without a history of AF. The inclusion criterion was CAD demanding CABG; the exclusion criteria were as follows: AF history, antiarrhythmic therapy in anamnesis, significant heart valve disease, severe renal failure and decompensating diabetes mellitus. The patients were randomised into 2 groups. Group I comprised 34 patients who underwent CABG alone, and Group II had 29 patients who underwent CABG combined with radiofrequency ablation (RFA) as the initial tool for POAF prevention. All the procedures were performed by a single surgical team using standardised anaesthetic and perfusion support.Results. There was no in-hospital mortality in either group. There were differences in the duration of the intervention, cardiopulmonary bypass time and the aorta clamping time between groups (p &gt; 0.05). A higher incidence of POAF was observed (11 %–32.4 %) in the isolated CABG group than in the CABG combined with PULVAB group (6 %–20.7 %), although the difference was not significant (p = 0.29). In most cases (91 %), AF occurred on the second to third postoperative day, irrespective of the observation group.Conclusion. The combination of CABG and RFA does not complicate the operation and does not increase the duration of the surgery or time of cardiopulmonary bypass. There were no significant differences in the postoperative course or the incidence and structure of complications between the groups. This may indicate the safety of our method. The positive tendency of POAF-cases decrease after preventive epicardial RFA observed in the present study allows us to continue the PULVAB study to gain more statistically significant results.Clin.Trials.gov Identifier: NCT03857711 Received 20 February 2020. Revised 29 June 2020. Accepted 2 July 2020. Funding: The study did not have sponsorship. Conflict of interest: Authors declare no conflict of interest. Author contributionsConception and design: A.Sh. Revishvili, V.A. PopovData collection and analysis: M.M. Anishchenko, E.S. Malyshenko, N.V. PopovaStatistical analysis: M.M. AnishchenkoDrafting the article: G.P. Plotnikov, M.M. AnishchenkoCritical revision of the article: A.Sh. Revishvili, V.A. PopovFinal approval of the version to be published: A.Sh. Revishvili, V.A. Popov, E.S. Malyshenko, G.P. Plotnikov, M.M. Anishchenko, N.V. Popova

P380Simultaneous endo-epicardial mapping of the human right atrium: unravelling 3-dimensional excitation

Abstract Funding Acknowledgements Prof. Dr. NMS de Groot is supported by funding grants from CVON-AFFIP (914728), NWO-Vidi (91717339), Biosense Webster USA (ICD 783454) and Medical Del Abstract Introduction &amp; Purpose Mapping studies demonstrated that endo-epicardial asynchrony (EEA) and conduction disorders, mainly longitudinal dissociation, play an important role in the pathophysiology of atrial fibrillation (AF). The aim of our study was therefore to investigate the correlation between features of conduction disorders assessed in the endo- and epicardial plane and the degree of EEA. Methods In 80 patients (63 male (79%), age 66 ± 9 years, 31 history of AF (39%)) undergoing cardiac surgery, simultaneous endo-epicardial mapping (256 electrodes, interelectrode distance:2mm) of the inferior, middle and superior right atrium (RA) was performed during SR. Areas of conduction block (CB) were defined as conduction delays of ≥12ms, EEA as activation time differences of opposite electrodes of ≥15ms and transmural CB as CB at similar endo-epicardial sites. Results Amount of CB was highest at the endocardium (endo median:1.9% [0-21.6] vs. epi median:1.1% [0-19.2], all locations p &amp;lt; 0.025) and was more pronounced at the superior RA. Amount of conduction block at both the endo-epicardium combined was higher at the superior RA in patients with hypertension (p = 0.046). Likewise, prevalence of transmural CB and EEA,-up to 84ms-, significantly increased from inferior to superior RA (all p &amp;lt; 0.001). Transmural CB at the inferior RA appeared to be associated with a higher incidence of post-operative AF (p = 0.03). Degree of EEA was also highest at superior RA (superior: 17.5ms [16-21.75] vs mid: 17ms [0-20] and inferior: 0ms [0-17], p &amp;lt; 0.001). Prevalence of CB was correlated with prevalence EEA (r= 0.74-0.87; all locations p &amp;lt; 0.001). In patients with hypertension (p = 0.009), diabetes (p = 0.015) and hypercholesterolemia (p = 0.015), EEA degree was higher at inferior RA. Significantly more CB (p = 0.007) and EEA (p = 0.037) were observed in patients with a history of persistent AF compared to patients without AF history. Conclusions This study provides important insights into the complex 3-dimensional endo-epicardial excitation and arrhythmogenesis. Knowledge of 3-dimensional excitation during SR is essential to understand the substrate underlying AF in order to improve (ablative) AF therapy.

Plasminogen activator inhibitor-1 as a predictor after cardiopulmonary bypass for postoperative atrial fibrillation

Background Following cardiac surgery, atrial fibrillation may be a common event. While postoperative atrial fibrillation (POAF) can be transient, it may lead to serious consequences, such as stroke, hemodynamic instability, and death. Plasminogen activator inhibitor-1 (PAI-1) serves as the primary inhibitor of tissue-type plasminogen activator, but also is mainly an acute-phase reactant. Increased PAI-1 promotes fibrosis and reduces extracellular matrix turnover, which modify the atrial substrate and potentially lead to POAF trigged by cardiac surgery. Aim The aim the study was to assess the efficacy of PAI-1 as a predictor of POAF after cardiopulmonary bypass (CPB). Patients and methods In this study, we enrolled 100 patients undergoing cardiac surgery requiring CPB and were in sinus rhythm at surgery time. Blood samples were obtained for the measurement of PAI-1 in the morning of the operation and immediately after separation from CPB and administration of protamine. Pearson’s χ2-test, Fisher’s exact test, area under the receiver operating characteristic curves, P-value less than 0.05, multivariable binary logistic regression were used. Results This study has shown that the serum level of preoperative PAI-1 more than 15 ng/ml and post-CPB level of PAI-1 more than 23 ng/ml are associated with high incidence of POAF (P 60 years) (P=0.04), hypertension history (P=0.035), number of grafts (P=0.01), Right Coronary Artery (RCA) graft (P Conclusion PAI-1 could be considered as a predictor of POAF whether measured preoperatively or postoperatively immediately after separation from CPB.

0058 : Low circulating levels of Growth Differentiation Factor 15 (GDF-15) before coronary artery bypass surgery may predict post-operative atrial fibrillation

Post-operative atrial fibrillation (POAF) following cardiac surgery has a high prevalence and is associated with considerable morbidity. To assess the role of GDF-15, a member of the TGFβsuperfamily, as a potential new predictor of POAF after off-pump (OFP) and on-pump (ONP) coronary artery bypass graft (CABG) surgery. This observational study recruited the first 50 patients planned for OFP surgery and the first 50 patients planned for ONP surgery. Patients referred for CABG with the following exclusion criteria: age <18 or >80 years, previous atrial fibrillation/flutter, previous treatment with Amiodarone, previous cardiac surgery, emergency surgery. Included patients were equipped with long-duration (7 days) Holter ECG monitoring. POAF was defined as an AF episode lasting >30 seconds. All patients underwent pre-operative echocardiography to assess LVEF and left atrial diameter. GDF-15 levels were assessed at induction of anaesthesia and 12 hours after the end of surgery. Among the 100 patients, 34 developed POAF. In Cox multivariate regression analysis, the EuroSCORE, left atrial diameter>45mm and low GDF- 15 levels at induction (<1200 ng/l) were independently associated with the onset of POAF. When comparing the incremental prognostic value of GDF-15 according to the time of blood sampling, we found that a low circulating level of GDF-15 at induction was a better predictor of POAF than that 12h later. In contrast, pre-operative NT-proBNP levels did not predict POAF. The use of ONP surgery was not associated with a higher incidence of POAF, even though baseline and follow-up characteristics in ONP and OFP patients were identical. In patients with no history of AF, a low plasma level of GDF- 15 before CABG surgery was a strong and independent predictor of POAF. Moreover, preoperative plasma GDF-15 levels added an incremental predictive value to classical risk factors of POAF.

Increased late mortality after coronary artery bypass surgery complicated by isolated new-onset atrial fibrillation: A comprehensive propensity-matched analysis

The association of new-onset postoperative atrial fibrillation (POAF) and late death after coronary artery bypass grafting (CABG) has been confounded by the frequent concomitant serious complications that co-occur with POAF. We aimed to define the magnitude and time dependence of the effect of isolated POAF on late survival after uncomplicated CABG to comprehensively account for comorbidity and perioperative confounding factors. Nonsalvage CABG patients with no history of AF, no concomitant aortic or valvular surgery, and no perioperative complications other than POAF were studied (n=6305). Patients were divided into AF (n=1211, 68 years old, 72% male) and no-AF (n=5094, 63 years old, 70% male) groups. Propensity matching was done using 55 patient variables, including coronary grafts, completeness of revascularization, and transfusion data. The AF effect was quantified using time-segmented hazard ratios by Cox regression analysis. Single (1-to-1), double (1-to-2), and triple (1-to-3) propensity matching of the AF and no-AF was achieved for 1196, 993, and 719 cases, respectively. The AF group showed significantly worse, yet time-varying, 0- to 18-year survival: 0 to 1 year, HR, 1.18 (95% confidence interval, 0.77-1.81); 1 to 6 years, HR, 1.37 (95% confidence interval, 1.12 to 1.67); and 6 to 17 years, HR, 1.25 (95% confidence interval, 1.05 to 1.49). Isolated POAF was associated with a time-varying increase in mortality after CABG. Given these findings and the high incidence of POAF, efforts to reduce POAF should be pursued to potentially improve resource usage, morbidity, and mortality.

Incidence and Predictors of Postoperative Atrial Fibrillation in Kidney Transplant Recipients

Postoperative atrial fibrillation (POAF) is a complication of cardiothoracic and noncardiothoracic surgery. Kidney transplant recipients bear several known risk factors and may have a higher incidence of POAF. We retrospectively studied kidney and kidney/liver transplant recipients to estimate their POAF incidence and identify relevant risk factors. We also adapted a clinical score originally designed to predict thromboembolic risk in atrial fibrillation (AF; CHA2DS2-VASc) for assessing transplant patients. We reviewed the clinical charts of kidney or kidney/liver transplant recipients from January 2005 to December 2008 at St. Orsola University Hospital Kidney Transplant Centre. Patients with and without POAF were compared on a number of clinical, laboratory, and instrumental data. The POAF incidence in kidney transplant recipients was 8.2%. Risk factors for POAF identified in univariate analyses included older recipient age, history of myocardial infarction, history of AF, liver/kidney transplantation, arterial stiffness, atherosclerotic plaques in the aorta or lower limbs, and diabetes mellitus. In a multivariate analysis, age, myocardial infarction history and combined liver/kidney transplantation were significant independent predictors of POAF. The modified CHA2DS2-VASc score proved to have a better predictive validity that the original CHA2DS2-VASc (area under the curve=0.71, 95% confidence interval=0.63-0.79 vs. area under the curve=0.62, 95% confidence interval=0.52-0.73, respectively). AF is a notable complication of kidney, and particularly simultaneous liver/kidney, transplant surgery. Age, previous myocardial infarction, and simultaneous liver/kidney transplant independently predicted POAF. The modified CHA2DS2-VASc score could be useful to predict POAF risk in kidney transplant candidates.

Obesity and Metabolic Syndrome Are Independent Risk Factors for Atrial Fibrillation After Coronary Artery Bypass Graft Surgery

Postoperative atrial fibrillation (POAF) is a highly prevalent complication after cardiac surgery with substantial effects on outcomes. Previous studies have reported that obesity is a risk factor for POAF after cardiac surgery. However, it is unknown whether the metabolic syndrome (MS) also increases the risk of postoperative atrial fibrillation. We retrospectively analyzed the association between obesity and MS and the incidence of new-onset POAF in a total of 5085 patients who underwent isolated coronary artery bypass grafting surgery with no concomitant valvular surgery. Of these patients, 1468 (29%) were obese (body mass index > or = 30 kg/m2) and 2320 (46%) had a MS as defined by the NCEP-ATPIII. POAF occurred in 1374 (27%) of the patients. Obesity was associated (P<0.001) with increased incidence of POAF in the whole cohort as well as in patients > 50 years old but not in patients < or = 50 years old. In these patients, MS was the only metabolic factor to be significantly associated with higher incidence of POAF (12% versus 6%, P=0.01). In > 50-year-old patients, mild (30 < or = body mass index < 35 kg/m2) and moderate-severe (body mass index > or = 35 kg/m2) obesity were independently associated with a 1.4-fold (95% CI: 1.10 to 1.71; P=0.004) and 2.3-fold (95% CI: 1.71 to 3.13; P<0.0001) increase in the risk of POAF, respectively. In < or = 50-year-old patients, MS (relative risk [RR]: 2.36; 95% CI: 1.10 to 5.12; P=0.02) but not obesity was independently associated with POAF. This study demonstrates that obesity is a powerful risk factor for the occurrence of POAF after isolated coronary artery bypass grafting surgery in patients older than 50 years. However, in the younger population, this association is not observed and MS is the only metabolic risk factor to be independently associated with POAF.

PREOPERATIVE BETA‐BLOCKER USE REDUCES ATRIAL FIBRILLATION IN OFF‐PUMP CORONARY BYPASS SURGERY

Atrial fibrillation (AF) after coronary artery bypass graft surgery constitutes the most common sustained arrhythmia and results in many complications. The purpose of this study was to assess the effects of prophylactic use of beta-blockers against atrial fibrillation in off-pump surgery patients in the early postoperative period. From 2002 to 2005, 78 patients were enrolled and 41 patients received 50 mg metoprolol succinate daily, which was initiated minimum four days before surgery. Preoperative beta-blocking therapy was continued until the morning of surgery. Thirty-seven patients were free of beta-blocker therapy. Esmolol was used within same range of doses in both groups during operations. Both groups received metoprolol succinate following operations. The frequency of AF occurrence was analysed from the operation time to the sixth postoperative day. Sixteen patients developed AF with an overall incidence of 22.5%. Four patients from the study group and three patients from the control group were excluded from the study because of transfer to on-pump surgery. There was no difference with regard to the number of grafts carried out, duration of operations and ventilation, intensive care unit stay and inotropic need among groups. Length of hospital stay did not differ among groups either. There was a higher incidence of postoperative AF in patients without beta-blocker prophylaxis (11.7-32.4% P=0.049). Low-dose postoperative beta-adrenergic blockade is valuable for patients who receive these medications before off-pump coronary artery bypass grafting procedures and may be beneficial against AF in all patients.

Role of postoperative use of adrenergic drugs in occurrence of atrial fibrillation after cardiac surgery

Use of adrenergic (inotropic and vasopressor) drugs is common after cardiac surgery. The study was undertaken to evaluate the role of postoperative adrenergic drug use as a predictor of postoperative atrial fibrillation (AF) after cardiac surgery. The study population consisted of 199 patients post cardiac surgery. Postoperative adrenergic drug use and the baseline and clinical variables were analyzed as possible predictors of postoperative AF. Of 199 patients, postoperative AF occurred in 59 patients (incidence 30%). The adrenergic drugs were used in 127 (64%) patients. Postoperative AF occurred in 49 of the 127 patients (39%) with and in 10 of the 72 patients (14%) without adrenergic drug use (p < 0.01). By univariate analyses, postoperative adrenergic drug use, age, left ventricular hypertrophy, left atrial size, valve surgery, aortic valve replacement, cross clamp time, bypass time, postoperative ventricular pacing, and hours in intensive care unit were predictors of development of postoperative AF. Atrial pacing was a predictor of freedom from developing AF. By multivariate logistic regression analysis, adrenergic drug use was an independent predictor of postoperative AF (odds ratio [OR] 3.35, 95% confidence interval [CI] 1.38-8.12, p = 0.016). Two other independent predictors were valve surgery (OR 2.88, 95% CI 1.31-6.35, p = 0.002) and age (OR 10.73, 95% CI 10.37-11.10, p = 0.0001). Adrenergic drug use, valve surgery, ventricular pacing, and age were predictors of time duration from surgery to the occurrence of AF. Drugs with predominantly beta1-adrenergic receptor affinity were associated with a higher incidence of postoperative AF (dopamine 44%, dobutamine 41% vs. phenylepherine 20%, p = 0.001). Use of adrenergic drugs is an independent predictor of postoperative AF after cardiac surgery.

Editorial: Atrial Fibrillation After Coronary Artery Bypass Grafting

Atrial fibrillation (AF) after coronary artery bypass surgery (CABG) is the most common sustained arrhythmia and the most common complication after CABG and consequently is a drain on hospital resources. Efforts to reduce the incidence of AF and the associated increased length of stay would result in substantial cost savings and decrease patient morbidity. 1 The incidence varies depending on the type of patient population involved. Age has been identified as the major independent predictor of post operative AF. Increasing age of patients accounts for the higher incidence of postoperative AF in recent years.2 Incidence of AF after CABG far exceeds the reported prevalence in the general population and in patients with coronary artery disease (CAD).3 Similarly, it is significantly higher than the reported incidence of AF after major noncardiac surgery regardless of CAD status.4 The pathophysiological mechanisms responsible for the high incidence of AF after CABG surgery is unclear. Some of the mechanisms suggested are sblocker withdrawal, the use of cardiopulmonary bypass, inadequate atrial protection, and overmanipulation of the right atrium1 Amiodarone has been increasingly used as an antiarrhythmic agent to prevent the occurrence of AF after cardiac surgery.5 Amiodarone seems to act through a prolongation of atrial refractoriness. However, the precise mechanism of action is not well understood because amiodarone does not predictably lengthen atrial repolarization acutely.6,7 It has been hypothesized that its effect may stem from its nonspecific antiadrenergic effect, its class I actions, or other actions not yet identified.6 Moreover, amiodarone has coronary vasodilatory effects8 that may benefit cardiac surgical patients. The response to amiodarone therapy for arrhythmia was found to be delayed in diabetic patients compared with that in non-diabetic patients undergoing coronary artery bypass grafting operation.9 This data from the current issue of the journal suggest a less pronounced sympatholytic effect of amiodarone treatment in diabetic patients undergoing CABG when compared with nondiabetic patients undergoing the same operation. Lervasi et al10 has demonstrated that the use of intravenous amiodarone loading dose in diabetic patients with cardiac arrhythmia has a later decrease in heart rate (after 4 days from the initiation of treatment) with a later antiarrhythmic positive response when compared with the results with nondiabetic arrhythmic patients who have a very early decrease in heart rate (within 4 hours of begining of treatment). Nondiabetic patients also have an early antiarrhythmic positive response (on average within 7 hours). Both these studies implicate the antiadrenergic effect of amiodarone in its antiarrhythmic action and the blunting of this response in diabetics, possibly due to autonomic dysfunction. Beta-blockers are useful for prevention of atrial fibrillation following cardiothoracic surgery, in which atrial fibrillation occurs in approximately 30% of patients11. The benefit of beta-blockade is greatest in patients who have received betablockers previously, although a reduction in atrial fibrillation is seen also in patients not previously on beta-blockers. The efficacy of beta-blockers in this situation is probably due to the elevated sympathetic tone present postoperatively. Betablockers protect against adrenergically mediated shortening of the action potential duration that is thought to help precipitate and maintain atrial fibrillation12. Another potential mechanism for preventing atrial fibrillation is suppression of pulmonary vein ectopy that triggers atrial fibrillation13. The use of magnesium in the preoperative and early postoperative periods has also been shown to be effective in reducing the incidence of AF after coronary artery bypass Editorial: Atrial Fibrillation After Coronary Artery Bypass Grafting 2 of 3 grafting.14 Postoperative AF occurred in 2 (2%) patients in the magnesium group and in 21 (21%) patients in the control group (p < 0.001). Patients in the magnesium group received 6 mmol MgSO4 infusion in 100 mL 0.9% NaCl solution (25 mL/h) the day before surgery, just after cardiopulmonary bypass, and once daily for 4 days after surgery. In a recent report, a novel intraoperative treatment strategy of both mechanical (leukocyte filtration) and pharmacological (aprotinin) intervention appears to markedly reduce the incidence of postcardiopulmonary bypass atrial fibrillation15 The proposed mechanism is that leukocyte depletion by filtration with the addition of aprotinin would reduce the systemic inflammatory effects of bypass and reduce the incidence of atrial fibrillation. The beneficial effects of the reduction of atrial fibrillation include reduced risk of embolism and lesser incidence of ischemia in the heart, lung and brain. In addition, there is a decrease in length of hospital stay, recovery time and overall cost. Hence more research into the mechanisms and treatment modalities of this most common postoperative arrhythmia is needed.