Predictors of atrial fibrillation after off-pump coronary artery bypass graft surgery

Predicting atrial fibrillation after cardiac surgery: a scoping review of associated factors and systematic review of existing prediction models

INTRODUCTION

Postoperative atrial fibrillation (POAF) is common after cardiac surgery and associated with increased hospital length of stay, patient morbidity and mortality. We aimed to identify factors associated with POAF and evaluate the accuracy of available POAF prediction models.

METHODS

We screened articles from Ovid MEDLINE® and PubMed Central® (PMC) and included studies that evaluated risk factors associated with POAF or studies that designed or validated POAF prediction models. We only included studies in cardiac surgical patients with sample size n ⩾ 50 and a POAF outcome group ⩾20. We summarised factors that were associated with POAF and assessed prediction model performance by reviewing reported calibration and discriminative ability.

RESULTS

We reviewed 232 studies. Of these, 142 fulfilled the inclusion criteria. Age was frequently found to be associated with POAF, while most other variables showed contradictory findings, or were assessed in few studies. Overall, 15 studies specifically developed and/or validated 12 prediction models. Of these, all showed poor discrimination or absent calibration in predicting POAF in externally validated cohorts.

CONCLUSIONS

Except for age, reporting of factors associated with POAF is inconsistent and often contradictory. Prediction models have low discrimination, missing calibration statistics, are at risk of bias and show limited clinical applicability. This suggests the need for studies that prospectively collect AF relevant data in large cohorts and then proceed to validate findings in external data sets.

Pericardial Effusion Provoking Atrial Fibrillation After Cardiac Surgery: JACC Review Topic of the Week

Postoperative atrial fibrillation (POAF) is the most common complication after cardiac surgery. Patients who develop POAF are more likely to experience adverse outcomes, including increased rates of death, stroke, heart failure, and hospitalizations, and higher hospital costs. Understanding the mechanisms underlying POAF is important to improve patients' outcome and optimize health systems' efficiency. Beyond classic pathogenic hypotheses, emerging evidence suggests that postoperative pericardial effusion and localized pericardial inflammation may trigger POAF. This hypothesis is supported by data from nonhuman animal models and a growing body of evidence showing that reducing postoperative pericardial effusion might reduce POAF incidence. In this review, we summarize the classic pathophysiology theories of POAF following cardiac surgery and discuss new etiologic mechanisms with a specific focus on the role of pericardial effusion and inflammation.

Perioperative risk factors for new-onset postoperative atrial fibrillation after coronary artery bypass grafting: a systematic review

Background

Postoperative atrial fibrillation (POAF) is the most common cardiac dysrhythmia to occur after coronary artery bypass grafting (CABG). However, the risk factors for new-onset POAF after CABG during the perioperative period have yet to be clearly defined. Accordingly, the aim of our systematic review was to evaluate the perioperative predictors of new-onset POAF after isolated CABG.

Method

Our review methods adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline. We searched seven electronic databases (PubMed, Embase, CINAHL, PsycArticles, Cochrane, Web of Science, and SCOPUS) to identify all relevant English articles published up to January 2020. Identified studies were screened independently by two researchers for selection, according to predefined criteria. The Newcastle–Ottawa Scale was used to evaluate the quality of studies retained.

Results

After screening, nine studies were retained for analysis, including 4798 patients, of whom 1555 (32.4%) experienced new-onset POAF after CABG. The incidence rate of new-onset POAF ranged between 17.3% and 47.4%. The following risk factors were identified: old age (p < 0.001), a high preoperative serum creatinine level (p = 0.001), a low preoperative hemoglobin level (p = 0.007), a low left ventricle ejection fraction in Asian patients (p = 0.001), essential hypertension (p < 0.001), chronic obstructive pulmonary disease (p = 0.010), renal failure (p = 0.009), cardiopulmonary bypass use (p = 0.002), perfusion time (p = 0.017), postoperative use of inotropes (p < 0.001), postoperative renal failure (p = 0.001), and re-operation (p = 0.005). All studies included in the analysis were of good quality.

Conclusions

The risk factors identified in our review could be used to improve monitoring of at-risk patients for early detection and treatment of new-onset POAF after CABG, reducing the risk of other complications and negative clinical outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02224-x.

Biochemical predictors of postoperative atrial fibrillation following cardiac surgery

Background

New-onset postoperative atrial fibrillation (POAF) is common after cardiac surgery. Early identification of its risk factors during the preoperative period would help in reducing the associated morbidity, mortality, and healthcare costs.

Aim of the study

This study aimed to identify the predictors of POAF following open cardiac surgery, with emphasis on biochemical parameters.

Methods

A total of 1191 patients with no preoperative atrial fibrillation (AF) and undergoing open cardiac surgery for any reason were included in this retrospective study. Data on clinical and biochemical parameters, the occurrence of new-onset AF, and its clinical course were retrieved from the hospital database.

Results

During the early postoperative period 330 patients (27.7%) developed atrial fibrillation, at median third postoperative day (range 1–6 days) and 217 (65.8%) responded to treatment. Multivariate analysis identified the following as the significant independent predictors of any POAF: EF < 60% (Odds ratio (OR), 2.6), valvular intervention (OR, 2.4), liver failure (OR, 2.4), diabetes (OR, 1.6), low hematocrit (OR, 2.1), low thrombocyte (OR, 5.6), low LDL (OR, 1.6), high direct bilirubin (OR, 2.0), low GFR (OR, 1.6), and high CRP (OR, 2.0). Following parameters emerged as significant independent predictors of persistent AF: EF < 60% (OR, 1.9), diabetes (OR, 2.1), COPD (OR, 1.8), previous cardiac surgery (OR, 3.1), valvular intervention (OR, 2.4), low hematocrit (OR, 1.9), low LDL (OR, 2.1), high HbA1c (OR, 2.0), and high CRP (OR, 2.7).

Conclusions

Certain parameters assessed during preoperative physical and laboratory examinations have the potential to be used as markers 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.

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.

Ten-Year Follow-Up of Off-Pump and On-Pump Multivessel Coronary Artery Bypass Grafting: MASS III

It was a randomized trial, and 308 patients undergoing revascularization were randomly assigned: 155 to off-pump coronary artery bypass (OPCAB) and 153 to on-pump coronary artery bypass (ONCAB). End points were freedom from death, myocardial infarction, revascularization, and cerebrovascular accidents. The rates for 10-year, event-free survival for ONCAB versus OPCAB were 69.6% and 64%, (hazard ratio [HR]: 0.88; 95% confidence interval [CI] 0.86-1.02; P = .41), respectively. Adjusted Cox proportional hazard ratio was similar (HR: 0.92; 95% CI 0.61-1.38, P = .68). A difference occurred between the duration of OPCAB and ONCAB, respectively (4.9 ± 1.5 vs 6.6 ± 1.1 h, P < .001). Statistical differences occurred between OPCAB and ONCAB in the length of intensive care unit (ICU) stay (20 ± 2.5 vs 48 ± 10 hours, P < .001), time to extubation (5.5 ± 4.2 vs 10.2 ± 3.5 hours, P < .001), hospital stay (6.7 ± 1.4 vs 9.2 ± 1.3 days, P < .001), higher incidence of atrial fibrillation (AF; 33 vs 5 patients, P < .001), and blood requirements (46 vs 64 patients, P < .001). Grafts per patient was higher in ONCAB (3.15 vs 2.55 grafts, P < .001). No difference existed between the groups in primary composite end points at 10-year follow-up. Although OPCAB surgery was related to a lower number of grafts and higher incidence of AF, it had no effects related to long-term outcomes.

Clinical and echocardiographic predicators of postoperative atrial fibrillation

BACKGROUND

Postoperative atrial fibrillation is the most common arrhythmia after coronary artery bypass grafting, with a reported incidence of 10% to 60%. Preoperative clinical and echocardiographic data, especially the atrial electromechanical interval, predict postoperative atrial fibrillation in elective coronary artery bypass patients.

METHODS

A prospective study evaluated preoperative clinical and echocardiographic data in 192 patients who underwent elective coronary artery bypass from 2010 to 2012.

RESULTS

18 (9.37%) patients developed postoperative atrial fibrillation. Compared to patients without postoperative atrial fibrillation, these 18 had significantly longer intensive care unit and hospital stays, they were significantly older (58.62 ± 10.02 vs. 53.22 ± 8.23 years; p = 0.02), with a larger left atrial volume (83.39 ± 8.31 vs. 55.47 ± 8.37 cm(3), p = 0.001), longer atrial electromechanical interval (133.67 ± 8.15 vs. 98.05 ± 6.71 ms p < 0.0001), and lower tissue Doppler imaging systolic velocity wave amplitude (6.6 ± 1 vs. 9.4 ± 2.2 cm·s(-1); p = 0.001); they also had a higher prevalence of hypertension (61.11% vs. 38.5%; p = 0.04). Using 115 ms as the cutoff value of atrial electromechanical interval enabled us to detect patients who developed postoperative atrial fibrillation with 100% sensitivity, 77% specificity, 78% positive predictive value, and 100% negative predictive value.

CONCLUSION

Older hypertensive patients are at higher risk of developing postoperative atrial fibrillation. Preoperative measurement of atrial electromechanical interval by tissue Doppler echocardiography is a useful predictor of postoperative atrial fibrillation in coronary artery bypass patients.

Post-operative atrial fibrillation: a maze of mechanisms

Post-operative atrial fibrillation (POAF) is one of the most frequent complications of cardiac surgery and an important predictor of patient morbidity as well as of prolonged hospitalization. It significantly increases costs for hospitalization. Insights into the pathophysiological factors causing POAF have been provided by both experimental and clinical investigations and show that POAF is ‘multi-factorial’. Facilitating factors in the mechanism of the arrhythmia can be classified as acute factors caused by the surgical intervention and chronic factors related to structural heart disease and ageing of the heart. Furthermore, some proarrhythmic mechanisms specifically occur in the setting of POAF. For example, inflammation and beta-adrenergic activation have been shown to play a prominent role in POAF, while these mechanisms are less important in non-surgical AF. More recently, it has been shown that atrial fibrosis and the presence of an electrophysiological substrate capable of maintaining AF also promote the arrhythmia, indicating that POAF has some proarrhythmic mechanisms in common with other forms of AF. The clinical setting of POAF offers numerous opportunities to study its mechanisms. During cardiac surgery, biopsies can be taken and detailed electrophysiological measurements can be performed. Furthermore, the specific time course of POAF, with the delayed onset and the transient character of the arrhythmia, also provides important insight into its mechanisms.

This review discusses the mechanistic interaction between predisposing factors and the electrophysiological mechanisms resulting in POAF and their therapeutic implications.

Five-year follow-up of a randomized comparison between off-pump and on-pump stable multivessel coronary artery bypass grafting. The MASS III Trial

BACKGROUND

Coronary artery bypass graft surgery with cardiopulmonary bypass is a safe, routine procedure. Nevertheless, significant morbidity remains, mostly because of the body's response to the nonphysiological nature of cardiopulmonary bypass. Few data are available on the effects of off-pump coronary artery bypass graft surgery (OPCAB) on cardiac events and long-term clinical outcomes.

METHODS AND RESULTS

In a single-center randomized trial, 308 patients undergoing coronary artery bypass graft surgery were randomly assigned: 155 to OPCAB and 153 to on-pump CAB (ONCAB). Primary composite end points were death, myocardial infarction, further revascularization (surgery or angioplasty), or stroke. After 5-year follow-up, the primary composite end point was not different between groups (hazard ratio 0.71, 95% CI 0.41 to 1.22; P=0.21). A statistical difference was found between OPCAB and ONCAB groups in the duration of surgery (240±65 versus 300±87.5 minutes; P<0.001), in the length of ICU stay (19.5±17.8 versus 43±17.0 hours; P<0.001), time to extubation (4.6±6.8 versus 9.3±5.7 hours; P<0.001), hospital stay (6±2 versus 9±2 days; P<0.001), higher incidence of atrial fibrillation (35 versus 4% of patients; P<0.001), and blood requirements (31 versus 61% of patients; P<0.001), respectively. The number of grafts per patient was higher in the ONCAB than the OPCAB group (2.97 versus 2.49 grafts/patient; P<0.001).

CONCLUSIONS

No difference was found between groups in the primary composite end point at 5-years follow-up. Although OPCAB surgery was related to a lower number of grafts and higher episodes of atrial fibrillation, it had no significant implications related to long-term outcomes. Clinical Trial Registration-URL: http://www.controlled-trials.com. Unique identifier: ISRCTN66068876.

Prevention of atrial fibrillation following cardiac surgery: basis for a novel therapeutic strategy based on non-hypoxic myocardial preconditioning

Atrial fibrillation is the most common complication of cardiac surgical procedures performed with cardiopulmonary bypass. It contributes to increased hospital length of stay and treatment costs. At present, preventive strategies offer only suboptimal benefits, despite improvements in anesthesia, surgical technique, and medical therapy. The pathogenesis of postoperative atrial fibrillation is considered to be multifactorial. However oxidative stress is a major contributory factor representing the unavoidable consequences of ischemia/reperfusion cycle occurring in this setting. Considerable evidence suggests the involvement of reactive oxygen species (ROS) in the pathogenic mechanism of this arrhythmia. Interestingly, the deleterious consequences of high ROS exposure, such as inflammation, cell death (apoptosis/necrosis) or fibrosis, may be abrogated by a myocardial preconditioning process caused by previous exposure to moderate ROS concentration known to trigger survival response mechanisms. The latter condition may be created by n-3 PUFA supplementation that could give rise to an adaptive response characterized by increased expression of myocardial antioxidant enzymes and/or anti-apoptotic pathways. In addition, a further reinforcement of myocardial antioxidant defenses could be obtained through vitamins C and E supplementation, an intervention also known to diminish enzymatic ROS production. Based on this paradigm, this review presents clinical and experimental evidence supporting the pathophysiological and molecular basis for a novel therapeutic approach aimed to diminish the incidence of postoperative atrial fibrillation through a non-hypoxic preconditioning plus a reinforcement of the antioxidant defense system in the myocardial tissue.

Trends in cardiac surgery: exploring the past and looking into the future

Today's successes would not be possible without the foundation of yesterday's practitioners and patients. This article assists in the exploration of cardiac surgery procedures, provides a brief historical review of the significant changes in cardiothoracic surgery, and provides an overview of current and future methods of treatment for coronary revascularization and heart failure. It is difficult for one article to encompass all aspects of cardiothoracic surgery. This article highlights many of the transforming moments that have led us to where we are today and explores the current trends of cardiac surgery and possibilities for tomorrow.

Predictors of atrial fibrillation after off-pump coronary artery bypass graft surgery

BACKGROUND

Postoperative atrial fibrillation (AF) is one of the most common complications after cardiothoracic surgery and is associated with an increased risk of stroke, and longer hospital stay. The pathophysiology of postoperative AF is uncertain, and its prevention remains unsatisfactory. Many previous studies have examined the predictors of AF after on-pump coronary artery bypass graft surgery (CABG), but there are few reports after off-pump CABG.

METHODS

The aim of the present prospective observational study, in which 296 consecutive patients were enrolled, was to elucidate the predictors of AF after off-pump CABG. The association of perioperative factors with AF was investigated using univariate analysis. Significant variables were included into a stepwise logistic regression model to ascertain their independent influence on the occurrence of AF.

RESULTS

The incidence of AF was 32%. AF prolonged the time until patients were fit for discharge by 3 days (P<0.01). Stepwise multivariate analysis identified increasing age [odds ratio (OR) 1.44 per 10-yr increase; 95% confidence interval (CI) 1.06-1.95], intraoperative average core temperature (OR 1.64; 95% CI 1.05-2.56), the average cardiac index in the intensive care unit (OR 0.37; 95% CI 0.19-0.71), and intraoperative fluid balance (OR 0.96 per 100-ml increase; 95% CI 0.93-0.99) as independent predictors of postoperative AF.

CONCLUSION

Our present findings indicate that ageing, the intraoperative fluid balance, and postoperative cardiac index are associated with the onset of AF after off-pump CABG.

Perioperative Amino Acid Infusion Improves Recovery and Shortens the Duration of Hospitalization After Off-Pump Coronary Artery Bypass Grafting

Perioperative amino acid infusion helps maintain core temperature and improves patient outcomes after gynecologic and orthopedic surgery. In the present study we prospectively determined the effect of amino acid infusion on esophageal core temperature and postoperative outcomes during off-pump coronary artery bypass grafting (CABG). One-hundred-eighty consecutive patients undergoing primary elective or urgent off-pump CABG were randomly divided into two groups: the i.v. amino acid infusion group (4 kJ kg(-1) h(-1) starting 2 h before surgery) and the saline infusion group (similar period and volume of saline infusion). The esophageal core temperature at the end of surgery was 35.6 (35.3-35.8) degrees C [mean (95% confidence interval)] in the saline infusion group and 36.1 degrees C (35.9-36.3) degrees C in the amino acid infusion group (P = 0.01). Kaplan-Meier analysis demonstrated that patients given amino acids required a significantly shorter duration of postoperative mechanical ventilation than patients given saline [median (95% confidence interval), 3.0 (2.5-3.9) vs 4.5 (3.8-5.8) h; P = 0.01]. Furthermore, intensive care unit stay [20 (19.5-38.4) vs 44 (21-45) h; P = 0.001] and days until fit for discharge from hospital [10 (9-11) vs 12 (11-13) days; P = 0.004] were significantly shorter in patients given amino acid. Perioperative amino acid infusion in patients undergoing off-pump CABG effectively minimizes intraoperative hypothermia and improves postoperative recovery.

Atrial fibrillation following cardiac surgery: a retrospective cohort series

Atrial fibrillation (AF) is a common postoperative complication of cardiac surgery, yet the prevention and treatment of postoperative AF remains controversial and varies among practitioners. The purpose of this study was to document the incidence and time of onset of postoperative AF in a cardiac surgical cohort, examine risk factors implicated in the occurrence of postoperative AF, and assess effectiveness of current treatment strategies implemented for postoperative AF. A retrospective health record review was conducted on 1078 adults following cardiac surgery. Data on demographic, preoperative, perioperative, and postoperative risk factors for postoperative AF, documented episodes of AF, and clinical outcomes were recorded. Overall incidence of postoperative AF was 39.6%: 57.6% after cardiac valve surgery, 69.3% after combined coronary artery bypass graft and valve surgery, and 33% after bypass graft surgery alone. The peak onset of postoperative AF occurred on the second postoperative day. Advancing age, history of AF, combined cardiac valve and coronary artery bypass graft surgery, and high Mg+2 levels on the third postoperative day were significant predictors of postoperative AF in this cohort. Length of hospitalization increased with the presence of postoperative AF. Findings corroborate that multiple factors play a role in the development of AF following cardiac surgery.

Cognitive and neurobehavioral dysfunction after cardiac bypass procedures

From a cognitive standpoint, CABG as currently practiced appears to be safe for the great majority of patients, but transient changes involving memory, executive functions, and motor speed may still occur in a subset of patients during the first few days to weeks after CABG. The etiology most likely is multifactorial and includes a synergistic effect of microemboli, hypo-perfusion, and other variables associated with major surgery. Older age and degree of pre-existing cerebrovascular disease have been identified as important risk factors. The short-term cognitive changes appear to be reversible by 3 months after surgery for most patients. Late cognitive decline after CABG,occurring between 1 and 5 years after the surgery, has been well documented,but controlled studies demonstrating that this decline is specifically attributable to the use of cardiopulmonary bypass itself rather than to progression of underlying cerebrovascular disease or other age-related changes are pending.

Perioperative Magnesium Supplementation to Prevent Atrial Fibrillation After Off-Pump Coronary Artery Surgery: A Randomized Controlled Study

OBJECTIVE

Atrial fibrillation is a common complication after cardiac surgery. Magnesium is an effective and safe antiarrhythmic agent for arrhythmias that develop after cardiac surgery. The authors performed a study to evaluate the role of perioperative magnesium for prophylaxis of atrial fibrillation after off-pump coronary artery surgery.

DESIGN

Randomized controlled study.

SETTING

University teaching hospital.

PARTICIPANTS

One hundred sixty consecutive patients undergoing elective, isolated, off-pump coronary artery bypass grafting were prospectively randomized into 2 groups.

INTERVENTIONS

Patients in the magnesium group (n = 80) received a 2.5-g (20 mEq) magnesium sulphate infusion intraoperatively over 30 minutes, and the placebo group (n = 80) received normal saline solution.

MEASUREMENTS AND MAIN RESULTS

Postoperative atrial fibrillation occurred in 16 of 80 patients (20%) in the magnesium group and in 18 of 80 (22.5%) in the placebo group (p = 0.9).

CONCLUSION

The use of 2.5 g of intraoperative magnesium showed no effect in preventing atrial fibrillation after off-pump coronary artery bypass.