Effect of perioperative corticosteroid use on the incidence of postcardiothoracic surgery atrial fibrillation and length of stay

Prevention of Atrial Fibrillation After Cardiac Surgery: A Review of Literature and Comparison of Different Treatment Modalities

Atrial fibrillation is the most common arrhythmia to occur after cardiac surgery, with an incidence of 10% to 50%. It is associated with postoperative complications including increased risk of stroke, prolonged hospital stays and increased costs. Despite new insights into the mechanisms of atrial fibrillation, no specific etiologic factor has been identified as the sole perpetrator of the arrhythmia. Current evidence suggests that the pathophysiology of atrial fibrillation in general, as well as after cardiac surgery, is multifactorial. Studies have also shown that new-onset postoperative atrial fibrillation following cardiac surgery is associated with a higher risk of short-term and long-term mortality. Furthermore, it has been demonstrated that prophylactic medical therapy decreases the incidence of postoperative atrial fibrillation after cardiac surgery. Of note, the incidence of postoperative atrial fibrillation has not changed during the last decades despite the numerous preventive strategies and operative techniques proposed, although the perioperative and postoperative care of cardiac patients as such has improved.

Inflammatory Biomarkers and Blood Physical Property Transformations Following On-Pump Coronary Artery Bypass Graft Surgery

OBJECTIVE

This study aimed to compare the hemorheological and inflammatory changes before and after coronary artery bypass graft (CABG) surgery, as factors such as hypothermia, hemodilution, transfusion, and other variables affect blood viscosity and inflammation during the procedure.

METHODS

A total of 25 patients who underwent CABG surgery were enrolled in this study. Whole blood was collected just before the CABG (D0), 2 days after surgery (D2), and 5 days after surgery (D5). The plasma viscosity (PV) and whole blood viscosity (WBV) were measured at shear rates ranging from 0.1 to 1000 s-1 using a rheometer, and the mean values were compared. Inflammatory markers were also assessed and analyzed in relation to the hemorheological changes.

RESULTS

Compared with the baseline values, the PV significantly increased after 5 days. WBV showed a significant increase on day 2 and after 5 days. The WBV and fibrinogen were significantly correlated on day 2 and day 5 but not before surgery. Inflammatory markers such as CRP, WBC, platelets, and fibrinogen also demonstrated notable changes in relation to the hemorheological alterations.

CONCLUSIONS

This study highlights the crucial finding that hyperviscosity, characterized by elevated PV and WBV, persists for almost one week after on-pump CABG surgery. Understanding the interplay between inflammation and hemorheological properties during the postoperative period is crucial for optimizing patient care. Future research should focus on exploring the underlying mechanisms and potential therapeutic interventions to mitigate the impact of inflammation on blood viscosity and improve patient outcomes following CABG surgery.

Effects of corticosteroids on new-onset atrial fibrillation after cardiac surgery: A meta-analysis of randomized controlled trials

BACKGROUND

Postoperative atrial fibrillation (POAF) occurs commonly after cardiac surgery. Studies suggest that corticosteroid can reduce the incident of POAF. However, the results remain controversial. This meta-analysis aimed to evaluate the efficacy and safety corticosteroid on the prevention of POAF following cardiac surgery.

METHODS

Randomized controlled trials were identified through a systematic literature search. Two investigators independently searched articles, extracted data, and assessed the quality of included studies. Primary outcome was the incidence of POAF as well as length of hospital stay and intensive care unit stay, wound and other infection, mortality, duration of ventilation, myocardial infarction, gastrointestinal complications, high blood sugar, stroke, and postoperative bleeding.

RESULTS

Fourteen studies with 13,803 patients were finally involved in the present study. Overall, corticosteroid significantly decreased the risk of POAF (relative risk [RR], 0.7; 95% confidence interval [CI], 0.55-0.89; P = .003). There were no significant differences in the incidence of length of intensive care unit stay (RR, -2.32; 95% CI, -5.44 to 0.80; P = .14) and hospital stay (RR, -0.43; 95% CI, -0.84 to -0.02; P = .04), infections (RR, 1.01; 95% CI, 0.83-1.23; P = .9), mortality (RR, 0.87; 95% CI, 0.71-1.06; P = .16), duration of ventilation (RR, -0.29; 95% CI, -0.65 to 0.07; P = .12), gastrointestinal complications (RR, 1.26; 95% CI, 0.91-1.76; P = .16), high blood sugar (RR, 1.98; 95% CI, 0.91-4.31; P = .09), stroke (RR, 0.9; 95% CI, 0.69-1.18; P = .45), postoperative bleeding (RR -44.54; 95% CI, -115.28 to 26.20; P = .22) and myocardial infarction (RR, 1.71; 95% CI, 0.96-1.43; P = .12).

CONCLUSION

Our review suggests that the efficacy of corticosteroid might be beneficial to POAF development in patients undergoing cardiac surgery. The strength of this association remains uncertain because of statistical and clinical heterogeneity among the included studies.

Systematic review of pre-clinical therapies for post-operative atrial fibrillation

BACKGROUND

Post-operative atrial fibrillation (POAF) is a frequent cardiothoracic surgery complication that increases hospital stay, mortality and costs. Despite decades of research, there has been no systematic overview and meta-analysis of preclinical therapies for POAF in animal models.

METHODS

We performed a systematic search of MEDLINE and EMBASE from their inception through September 2020 to determine the effect of preclinical POAF therapies on primary efficacy outcomes using a prospectively registered protocol (CRD42019155649). Bias was assessed using the SYRCLE tool and CAMARADES checklist.

RESULTS

Within the 26 studies that fulfilled our inclusion criteria, we identified 4 prevention strategies including biological (n = 5), dietary (n = 2), substrate modification (n = 2), and pharmacological (n = 17) interventions targeting atrial substrate, cellular electrophysiology or inflammation. Only one study altered more than 1 pathophysiological mechanism. 73% comprised multiple doses of systemic therapies. Large animal models were used in 81% of the studies. Preclinical therapies altogether attenuated atrial fibrosis (SMD -2.09; 95% confidence interval [CI] -2.95 to -1.22; p < 0.00001; I2 = 47%), AF inducibility (RR 0.40; 95% CI 0.21 to 0.79; p = 0.008; I2 = 39%), and AF duration (SMD -2.19; 95% CI -3.05 to -1.32; p < 0.00001; I2 = 50%). However, all the criteria needed to evaluate the risk of bias was unclear for many outcomes and only few interventions were independently validated by more than 1 research group.

CONCLUSION

Treatments with therapies targeting atrial substrate, cellular electrophysiology or inflammation reduced POAF in preclinical animal models compared to controls. Improving the quality of outcome reporting, independently validating promising approaches and targeting complimentary drivers of POAF are promising means to improve the clinical translation of novel therapies for this highly prevalent and clinically meaningful disease.

[Atrial Fibrillation After Coronary Artery Bypass Surgery: Risk Factors, Prevention and Treatment]

This review focuses on the issue of atrial fibrillation (AF) following coronary bypass surgery in patients with ischemic heart disease. Risk factors of this complication are discussed in detail. The authors addressed the effect of diabetes mellitus on development of postoperative AF. Data on current methods for prevention and treatment of AF are provided.

New-onset postoperative atrial fibrillation after heart surgery

BACKGROUND

New-onset postoperative atrial fibrillation (poAF) complicates approximately 20-60% of all cardiac surgical procedures and is associated with an increased periprocedural mortality and morbitity, prolonged hospital stay, increased costs, and worse long-term survival. Unfortunately multiple advances in surgery and perioperative care over the last two decades have not led to a reduction in the incidence of poAF or associated complications in the daily clinical practice.

METHODS

A narrative review of the available literature was performed.

RESULTS

An extensive review of the pathophysiology of poAF following cardiac surgery, clinical, and procedural risk-factors is provided, as well as prophylactic measures and treatment.

CONCLUSION

Multiple strategies to prevent and manage poAF following heart surgery already exist. Our hope is that this review will facilitate more rigorous testing of prevention strategies, implementation of prophylaxis regimens as well as optimal treatment of this common and serious complication.

Anti-inflammatory drugs in the prevention of post-operative atrial fibrillation: a literature review

Atrial fibrillation (AF) is a serious and common complication following heart surgery. Cardiac surgery triggers inflammation in the heart and makes it susceptible to the incidence of AF. Therefore, anti-inflammatory drugs may reduce the rate of AF incidence in the post-surgery conditions. Immunosuppressant agents, steroidal anti-inflammatory drugs (corticosteroids), non-aspirin non-steroid anti-inflammatory drugs (NSAIDs), colchicine and omega-3 unsaturated fatty acids (n-3 UFA) are drugs with well-known anti-inflammatory properties. The efficacy, safety and other aspects of using these drugs in the prevention of post-operative AF (POAF) have been reviewed here. Studies evaluating the efficacy of colchicine have shown that it could be effective in the prevention of POAF. However, there is a need for additional studies to find a colchicine regimen with optimal efficacy and higher tolerability. The use of corticosteroids may also be of value based on the most of meta-analyses. In the case of n-3 polyunsaturated fatty acids and NSAIDs, current data fail to support their efficacy in POAF prevention. Moreover, perioperative administration of NSAIDs may be associated with some severe safety considerations. Immunosuppressant agents have not been used for the prevention of POAF. Further studies are needed to find the most effective strategy for POAF prevention with the least safety considerations and the highest health benefits.

N-acetylcysteine use among patients undergoing cardiac surgery: A systematic review and meta-analysis of randomized trials

Background

Cardiac surgeries are complex procedures aiming to re-establish coronary flow and correct valvular defects. Oxidative stress, caused by inflammation and ischemia-reperfusion injury, is associated with these procedures, increasing the risk of adverse outcomes. N-acetylcysteine (NAC) acts as an antioxidant by replenishing the glutathione stores, and emerging evidence suggests that NAC may reduce the risk of adverse perioperative outcomes. We conducted a systematic review and meta-analysis to investigate the addition of NAC to a standard of care among adult patients undergoing cardiac surgery.

Methods

We searched four databases (PubMed, EMBASE, CENTRAL, LILACS) from inception to October 2018 and the grey literaure for randomized controlled trials (RCTs) investigating the effect of NAC on pre-defined outcomes including mortality, acute renal insufficiency (ARI), acute cardiac insufficiency (ACI), hospital length of stay (HLoS), intensive care unit length of stay (ICULoS), arrhythmia and acute myocardial infarction (AMI). Reviewers independently screened potentially eligible articles, extracted data and assessed the risk of bias among eligible articles. We used the GRADE approach to rate the overall certainty of evidence for each outcome.

Results

Twenty-nine RCTs including 2,486 participants proved eligible. Low to moderate certainty evidence demonstrated that the addition of NAC resulted in a non-statistically significant reduction in mortality (Risk Ratio (RR) 0.71; 95% Confidence Interval (CI) 0.40 to 1.25), ARI (RR 0.92; 95% CI 0.79 to 1.09), ACI (RR 0.77; 95% CI 0.44 to 1.38), HLoS (Mean Difference (MD) 0.21; 95% CI -0.64 to 0.23), ICULoS (MD -0.04; 95% CI -0.29 to 0.20), arrhythmia (RR 0.79; 95% CI 0.52 to 1.20), and AMI (RR 0.84; 95% CI 0.48 to 1.48).

Limitations

Among eligible trials, we observed heterogeneity in the population and interventions including patients with and without kidney dysfunction and interventions that differed in route of administration, dosage, and duration of treatment. This observed heterogeneity was not explained by our subgroup analyses.

Conclusions

The addition of NAC during cardiac surgery did not result in a statistically significant reduction in clinical outcomes. A large randomized placebo-controlled multi-centre trial is needed to determine whether NAC reduces mortality.

Registration

PROSPERO CRD42018091191.

Impact of a Perioperative Prophylaxis Guideline on Post-Cardiothoracic Surgery Atrial Fibrillation

BACKGROUND

National practice guidelines do not provide clear recommendations on combination pharmacological regimens to reduce cardiothoracic surgery (CTS) postoperative atrial fibrillation (POAF).

OBJECTIVE

This study examines if there is a reduction in POAF rates after implementing a perioperative prophylaxis guideline that includes amiodarone, β-blockers, and high-intensity statins.

METHODS

Data were retrospectively collected on 400 adults (200 patients pre-guideline implementation and 200 patients post-guideline implementation) with a CHA₂DS₂-VASc (Congestive Heart Failure, Hypertension, Age, Diabetes Mellitus, and Vascular Disease) score of at least 3 points after CTS. Data were collected on the incidence of POAF lasting more than 5 minutes and secondary outcomes, including the length of hospitalization, guideline adherence rate, adverse events, and timeliness of POAF treatment.

RESULTS

Guideline implementation increased prophylactic amiodarone ( P < 0.0001), statin ( P = 0.029), and high-intensity statin ( P = 0.002) use without changing β-blocker use (64.5% vs 67.0%, P = 0.673) and reduced POAF (39.5% vs 52.0%, P = 0.016) and ventricular tachycardia (15.5% vs 24.5%, P = 0.034) compared with preguideline rates. Length of hospitalization and other postoperative adverse events, including stroke and mortality, were not statistically different. Subgroup analyses of patients who were adherent to both the amiodarone and β-blocker recommendations (28% of the total) or to all 3 recommended therapies (24% of the total) had significant decreases in POAF ( P = 0.001; P < 0.001), length of hospitalization ( P = 0.023; P = 0.049), length of intensive care unit stay ( P = 0.045; P = 0.040), and ventricular tachycardia ( P = 0.008; P = 0.017) compared with preguideline patients, respectively.

CONCLUSIONS

A perioperative guideline of amiodarone, β-blockers, and high-intensity statins reduced POAF, but better benefits may result from enhanced adherence.

Pharmacology of Acetaminophen, Nonsteroidal Antiinflammatory Drugs, and Steroid Medications: Implications for Anesthesia or Unique Associated Risks

Acetaminophen, nonsteroidal antiinflammatory drugs (NSAIDs), and corticosteroids, historically used in perioperative management, are potent analgesic medications. They primarily inhibit the cyclooxygenase (COX) enzyme, decreasing the synthesis of prostaglandins, and modulating pain and temperature. Acetaminophen does not inhibit this synthesis at the inflammatory site. The primary mechanism of action of corticosteroids involves regulation of nuclear expression of genes involved in inflammatory pathways and other systemic effects. Metaanalyses have added purposeful perioperative indications, clarified misconceptions, and established protocols for administering these drugs. Some indications, doses, clinical considerations, and adverse effects need to be further studied.

Pharmacological strategies for prevention of postoperative atrial fibrillation

Atrial fibrillation (AF) complicating cardiac surgery continues to be a major problem that increases the postoperative risk of stroke, myocardial infarction, heart failure and costs and can affect long-term survival. The incidence of AF after surgery has not significantly changed over the last two decades, despite improvement in medical and surgical techniques. The mechanism and pathophysiology underlying postoperative AF (PoAF) is incompletely understood and results from a combination of acute and chronic factors, superimposed on an underlying abnormal atrial substrate with increased interstitial fibrosis. Several anti-arrhythmic and non-anti-arrhythmic medications have been used for the prevention of PoAF, but the effectiveness of these strategies has been limited due to a poor understanding of the basis for the increased susceptibility of the atria to AF in the postoperative setting. In this review, we summarize the pathophysiology underlying the development of PoAF and evidence behind pharmacological approaches used for its prevention in the postoperative setting.

Comparison of two different doses of single bolus steroid injection to prevent atrial fibrillation recurrence after radiofrequency catheter ablation

PURPOSE

Steroids may play a role in preventing the early recurrence of atrial fibrillation (AF) after radiofrequency catheter ablation (RFCA). However, optimal doses and route of steroid delivery have not yet been determined. This study evaluated the effect of two different doses of a single bolus injection of steroids on AF recurrence after RFCA.

MATERIALS AND METHODS

Of 448 consecutive AF patients who underwent RFCA, a single steroid bolus was injected into 291 patients. A low-dose steroid group (n=113) received 100 mg of hydrocortisone and a moderate-dose steroid group (n=174) received 125 mg of methylprednisolone. We used propensity-score matching to select patients as follows: control (n=95), low-dose (n=95), and moderate-dose steroid groups (n=97).

RESULTS

Pericarditis developed in 1 (1.1%) control patient, 2 (2.1%) low-dose patients and 0 moderate-dose patients. Maximum body temperature and C-reactive protein were significantly decreased in the moderate-dose steroid group compared to the other groups (p<0.01). The number of patients of early AF recurrence (≤3 months) did not differ among three groups. Early recurrence was 24 (25%) in the control, 24 (25%) in the low-dose and 25 (26%) in the medium-dose groups (p=0.99). Compared with control group, low-dose or moderate-dose steroid treatment did not effectively decrease mid-term (3-12 months) AF recurrence [22 (23%) vs. 23 (24%) vs. 18 (19%); p=0.12].

CONCLUSION

A single injection of moderate-dose steroid decreased inflammation. However, single bolus injections of low-dose or moderate-dose steroids were not effective in preventing immediate, early or midterm AF recurrence after RFCA.

Role of inflammation in atrial fibrillation pathophysiology and management

Atrial fibrillation (AF) is the most common clinically relevant arrhythmia, but the methods available for treating AF and its complications (of which the most important is thrombogenesis), as well as for assessing AF risk and underlying pathophysiology, are largely limited. Emerging evidence suggests a significant role of inflammation in the pathogenesis of AF. That evidence includes elevated serum levels of inflammatory biomarkers in AF subjects, the expression of inflammatory markers in cardiac tissues of AF patients and animal models of AF, and beneficial effects of anti-inflammatory drugs in experimental AF paradigms. Inflammation is suggested to be linked to various pathological processes, such as oxidative stress, apoptosis, and fibrosis, that promote AF substrate formation. Inflammation has also been associated with endothelial dysfunction, platelet activation, and coagulation cascade activation, leading to thrombogenesis. Thus, inflammation may contribute to both the occurrence/maintenance of AF and its thromboembolic complications. Here, we review the evidence for a role of inflammation and inflammatory biomarkers in the risk management and treatment of AF. We also summarize the current knowledge of inflammation-dependent cellular and molecular mechanisms in AF pathophysiology and their potential as therapeutic targets.

Predicting New-Onset Postoperative Atrial Fibrillation in Cardiac Surgery Patients

OBJECTIVE

To derive a simple clinical prediction rule identifying patients at high risk of developing new-onset postoperative atrial fibrillation (POAF) after cardiac surgery.

DESIGN

Retrospective analysis on prospectively collected observational data.

SETTING

A university-affiliated cardiac hospital.

PARTICIPANTS

Adult patients undergoing coronary artery bypass grafting and/or valve surgery.

INTERVENTIONS

Observation for the occurrence of new-onset postoperative atrial fibrillation.

MEASUREMENTS AND MAIN RESULTS

Details on 28 preoperative variables from 999 patients were collected and significant predictors (p<0.2) were inserted into multivariable logistic regression and reconfirmed with recursive partitioning. A total of 305 (30.5%) patients developed new-onset POAF. Eleven variables were associated significantly with atrial fibrillation. A multivariable logistic regression model included left atrial dilatation, mitral valve disease, and age. Coefficients from the model were converted into a simple 7-point predictive score. The risk of POAF per score is: 15.0%, if 0; 20%, if 1; 27%, if 2; 35%, if 3; 44%, if 4; 53%, if 5; 62%, if 6; and 70%, if 7. A score of 4 has a sensitivity of 44% and a specificity of 82% for POAF. A score of 6 has a sensitivity of 11% and a specificity of 97%. Bootstrapping with 5,000 samples confirmed the final model provided consistent predictions.

CONCLUSIONS

This study proposed a simple predictive score incorporating three risk variables to identify cardiac surgical patients at high risk of developing new-onset POAF. Preventive treatment should target patients ≥ 65 years with left atrial dilatation and mitral valve disease.

The efficacy of glucocorticoids for the prevention of atrial fibrillation, or length of intensive care unite or hospital stay after cardiac surgery: a meta-analysis

AIMS

cardiopulmonary bypass and cardiac surgery are associated with a significant systemic inflammatory response that has been suggested playing a causative role in the development of perioperative atrial fibrillation (POAF). The goal of this meta-analysis was to determine the efficacy of glucocorticoid prophylaxis in preventing POAF, or length of intensive care unite (ICU) or hospital stay.

METHODS

A systematic electronic database literature search of Cochrane controlled trials register (2013, issue 4) and MEDLINE (1966 to April, 2013) was conducted using specific search terms for all relevant articles. Including criteria were: randomized controlled clinical trials, participants were adults (≥18 years of age) undergoing cardiac surgery, evaluated glucocorticoid prophylaxis in cardiac surgery with adequately reported data on incidence of POAF, or length of ICU or hospital stay.

RESULTS

Forty-two randomized controlled trials involving 7621 participants were included in the meta-analysis. Overall, glucocorticoids prophylaxis significantly lowered participants' risk of developing POAF (Relative Risk [RR] 0.77; 95% confidence interval [CI] 0.66-0.90), P < 0.01), reduced length of ICU stay by 0.25 day (95% CI -0.40 to -0.10, P < 0.01). Glucocorticoid prophylaxis in cardiac surgery was not associated with increased all-cause of infection (RR 0.68; 95% CI 0.58-0.78, P < 0.01) and mortality (RR 0.75; 95% CI 0.52-1.08, P = 0.12).

CONCLUSIONS

Pooled evidence suggests that glucocorticoid prophylaxis may reduce the incidence of POAF. The beneficial effect on POAF is associated with reduced length of ICU and hospital stay, and infection rate.

Is perioperative corticosteroid administration associated with a reduced incidence of postoperative atrial fibrillation in adult cardiac surgery?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: Is perioperative corticosteroid administration associated with a reduced incidence of postoperative atrial fibrillation (POAF) in adult cardiac surgery? A total of 70 papers were identified using the search as described below. Of these, eight were identified to provide best evidence to answer the clinical question. These papers consisted of well-designed, double-blinded randomized control trials (RCTs) or meta-analysis of RCTs that presented sufficient data to reach conclusions regarding the issues of interest for this review. Postoperative atrial fibrillation occurrence, outcomes and complications were included in the assessment. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of the papers are tabulated. Literature search showed that the prophylactic use of hydrocortisone (100 mg/day, 4 days) can reduce the incidence of POAF to 30%, compared with 48% in the control group (P = 0.004). One gram of methylprednisolone before surgery followed by 4 mg of dexamethasone every 6 h for 1 day after surgery was also associated with a significant reduction in POAF (21 vs 51%; P = 0.003). Moreover, a single dose of dexamethasone (0.6 mg/kg) can significantly diminish POAF (18.95 vs 32.3%; P = 0.027). The changes in POAF appeared greatest in patients receiving intermediate doses of corticosteroid (50-210 mg of dexamethasone equivalent), while both lower (up to 8 mg) and higher (236-2850 mg) dosing resulted in blunted effects. Similarly, a moderate dose of hydrocortisone (200-1000 mg/day) is as effective as high (1001-10 000 mg/day) and very high doses (10 000 mg/day). Although the optimal dose, dosing interval and duration of therapy are unclear, meta-analysis suggests that a single dose can be as effective as multiple doses. No statistically significant complications associated with the use of corticosteroids were reported in any of the studies. We conclude that a single prophylactic moderate dose of corticosteroid (50-210 mg of dexamethasone equivalent or 200-1000 mg/day hydrocortisone) can significantly reduce the risk of POAF with no significant increase in morbidity or mortality.

Glucocorticoids in adult cardiac surgery; old drugs revisited

Glucocorticoids can play a pivotal role in modulating different immune responses. The role of glucocorticoids in cardiac surgery is still controversial as many surgeons are concerned about the potential side effects.

In this review, we looked at the role of glucocorticoid administration in modulating postoperative inflammatory responses, atrial fibrillation (AF) and intimal hyperplasia and whether glucocorticoid use is associated with a significant increase in undesirable postoperative complication.

Primary Prevention of Atrial Fibrillation where are we in 2012?

Drugs to alter or delay myocardial remodelling associated with heart failure, hypertension, or inflammation in the post-operative setting, may prevent the development of atrial fibrillation. Current experimental and clinical evidences support specific treatments for defined patient population (i.e. ACE-inhibitors and ARB for chronic heart failure and hypertension expecially with LV hypertrophy; statins, corticosteroids and possibly colchicine after cardiac surgery).

IntravenousCorticosteroid Use Is Associated With Reduced Early Recurrence of Atrial Fibrillation Immediately Following Radiofrequency Catheter Ablation

Background: Early recurrence of atrial fibrillation (ERAF) occurs in up to 40% of patients after radiofrequency catheter ablation for atrial fibrillation (RFCA), increasing hospital stay, need for anti-arrhythmic medications (AADs) and cardioversion, and, possibly, the risk of future AF. It has been postulated that inflammation plays a key role in developing ERAF. Short term postoperative use of corticosteroids to reduce ERAF post-RFCA has not been vigorously studied. Methods: This was a case-control study of consecutive patients undergoing RFCA for the management of AF at a single-institution. RFCA was performed by a single operator from October 2005 through July 2009. Patients receiving intravenous corticosteroids immediately following the ablation and for 48 hours (6 doses) constituted the treatment group. Controls received no intravenous corticosteroids during their hospitalization. All other management strategies were similar between the 2 groups, including the administration of AADs post- operatively. All patients had continuous electrocardiographic monitoring throughout their hospitalization. Multivariable logistic regression analysis was used to determine the impact of intravenous corticosteroids on ERAF defined as any AF>10 minutes during hospitalization. Results: A total of 68 patients undergoing RFCA for the management of AF were included in this analysis. The overall ERAF rate, irrespective of intravenous corticosteroid use, was 23.5%. The administration of intravenous corticosteroids (n=37; mean±SD dexamethasone mean dose 11.9±4.6 mg/day; range 4-16 mg/day) was associated with an 82% reduction in patients' odds of ERAF (adjusted odds ratio; 0.18, 95% confidence interval [CI] 0.04 to 0.78) compared with those who did not receive corticosteroids (n=31). A dose-response effect was also observed, with a 17% reduction in ERAF odds for each dexamethasone mg-equivalent administered (adjusted odds ratio; 0.83, 95%CI 0.73 to 0.96). Conclusions: The use of intravenous corticosteroids was associated with a dose-dependent reduction in the odds of developing ERAF after RFCA for the management of AF.

Upstream therapies for management of atrial fibrillation: review of clinical evidence and implications for European Society of Cardiology guidelines. Part I: primary prevention

Atrial fibrillation (AF) is associated with significant morbidity and mortality. It is also a progressive disease secondary to continuous structural remodelling of the atria due to AF itself, to changes associated with ageing, and to deterioration of underlying heart disease. Current management aims at preventing the recurrence of AF and its consequences (secondary prevention) and includes risk assessment and prevention of stroke, ventricular rate control, and rhythm control therapies including antiarrhythmic drugs and catheter or surgical ablation. The concept of primary prevention of AF with interventions targeting the development of substrate and modifying risk factors for AF has emerged as a result of recent experiments that suggested novel targets for mechanism-based therapies. Upstream therapy refers to the use of non-antiarrhythmic drugs that modify the atrial substrate- or target-specific mechanisms of AF to prevent the occurrence or recurrence of the arrhythmia. Such agents include angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), statins, n-3 (ω-3) polyunsaturated fatty acids, and possibly corticosteroids. Animal experiments have compellingly demonstrated the protective effect of these agents against electrical and structural atrial remodelling in association with AF. The key targets of upstream therapy are structural changes in the atria, such as fibrosis, hypertrophy, inflammation, and oxidative stress, but direct and indirect effects on atrial ion channels, gap junctions, and calcium handling are also applied. Although there have been no formal randomized controlled studies (RCTs) in the primary prevention setting, retrospective analyses and reports from the studies in which AF was a pre-specified secondary endpoint have shown a sustained reduction in new-onset AF with ACEIs and ARBs in patients with significant underlying heart disease (e.g. left ventricular dysfunction and hypertrophy), and in the incidence of AF after cardiac surgery in patients treated with statins. In the secondary prevention setting, the results with upstream therapies are significantly less encouraging. Although the results of hypothesis-generating small clinical studies or retrospective analyses in selected patient categories have been positive, larger prospective RCTs have yielded controversial, mostly negative, results. Notably, the controversy exists on whether upstream therapy may impact mortality and major non-fatal cardiovascular events in patients with AF. This has been addressed in retrospective analyses and large prospective RCTs, but the results remain inconclusive pending further reports. This review provides a contemporary evidence-based insight into the role of upstream therapies in primary (Part I) and secondary (Part II) prevention of AF.

Prophylactic corticosteroids for cardiopulmonary bypass in adults

BACKGROUND

High-dose prophylactic corticosteroids are often administered during cardiac surgery. Their use, however, remains controversial, as no trials are available that have been sufficiently powered to draw conclusions on their effect on major clinical outcomes.

OBJECTIVES

The objective of this meta-analysis was to estimate the effect of prophylactic corticosteroids in cardiac surgery on mortality, cardiac and pulmonary complications.

SEARCH STRATEGY

Major medical databases (CENTRAL, MEDLINE, EMBASE, CINAHL and Web of Science) were systematically searched for randomised studies assessing the effect of corticosteroids in adult cardiac surgery. Database were searched for the full period covered, up to December 2009. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials comparing corticosteroid treatment to either placebo treatment or no treatment in adult cardiac surgery were selected. There were no restrictions with respect to length of the follow-up period. All selected studies qualified for pooling of results for one or more end-points.

DATA COLLECTION AND ANALYSIS

The processes of searching and selection for inclusion eligibility were performed independently by two authors. Also, quality assessment and data-extraction of selected studies were independently performed by two authors. The primary endpoints were mortality, cardiac and pulmonary complications. The main effect measure was the Peto odds ratio comparing corticosteroids to no treatment/placebo.

MAIN RESULTS

Fifty-four randomised studies, mostly of limited quality, were included. Altogether, 3615 patients were included in these studies. The pooled odds ratio for mortality was 1.12 (95% CI 0.65 to 1.92), showing no mortality reduction in patients treated with corticosteroids. The odds ratios for myocardial and pulmonary complications were 0.95, (95% CI 0.57 to 1.60) and 0.83 (95% CI 0.49 to 1.40), respectively. The use of a random effects model did not substantially influence study results. Analyses of secondary endpoints showed a reduction of atrial fibrillation and an increase in gastrointestinal bleeding in the corticosteroids group.

AUTHORS' CONCLUSIONS

This meta-analysis showed no beneficial effect of corticosteroid use on mortality, cardiac and pulmonary complications in cardiac surgery patients.

Pathophysiological mechanisms of atrial fibrillation: a translational appraisal

Atrial fibrillation (AF) is an arrhythmia that can occur as the result of numerous different pathophysiological processes in the atria. Some aspects of the morphological and electrophysiological alterations promoting AF have been studied extensively in animal models. Atrial tachycardia or AF itself shortens atrial refractoriness and causes loss of atrial contractility. Aging, neurohumoral activation, and chronic atrial stretch due to structural heart disease activate a variety of signaling pathways leading to histological changes in the atria including myocyte hypertrophy, fibroblast proliferation, and complex alterations of the extracellular matrix including tissue fibrosis. These changes in electrical, contractile, and structural properties of the atria have been called "atrial remodeling." The resulting electrophysiological substrate is characterized by shortening of atrial refractoriness and reentrant wavelength or by local conduction heterogeneities caused by disruption of electrical interconnections between muscle bundles. Under these conditions, ectopic activity originating from the pulmonary veins or other sites is more likely to occur and to trigger longer episodes of AF. Many of these alterations also occur in patients with or at risk for AF, although the direct demonstration of these mechanisms is sometimes challenging. The diversity of etiological factors and electrophysiological mechanisms promoting AF in humans hampers the development of more effective therapy of AF. This review aims to give a translational overview on the biological basis of atrial remodeling and the proarrhythmic mechanisms involved in the fibrillation process. We pay attention to translation of pathophysiological insights gained from in vitro experiments and animal models to patients. Also, suggestions for future research objectives and therapeutical implications are discussed.

Review: Beyond the Guidelines: New and Novel Agents for the Prevention of Atrial Fibrillation After Cardiothoracic Surgery

Postoperative atrial fibrillation (POAF), a common complication of cardiac surgery, can increase the morbidity and mortality, as well as the costs of the surgery being preformed. Guidelines recommend the use of β-blockers, amiodarone, or sotalol to decrease the risk of experiencing POAF. However, none of these agents fully protect the patient from POAF, thus newer agents are needed to be used in combination with them. Many different agents have been studied to fit this role and may be grouped into 2 categories: agents with antiarrhythmic activity such as magnesium and polyunsaturated fatty acids and agents with anti-inflammatory activity such as statins and free radical scavengers. Most of these novel agents have been studied in a wide variety of trials; however, some clearly have more effect than others. Although none of these newer agents have the data required to make blanket recommendations for use at this point, given the safety profile and low costs of some, many continue to be evaluated in randomized-controlled trials.

High-sensitivity C-reactive protein as a predictor of atrial fibrillation recurrence after primary circumferential pulmonary vein isolation

BACKGROUND

Atrial fibrillation (AF) recurrence after circumferential pulmonary vein isolation (CPVI) is difficult to predict. Inflammation is associated with the development of AF. Inflammatory markers, such as high sensitivity C-reactive protein (hsCRP), are related to AF development via atrial remodeling. However, it is unknown whether plasma hsCRP concentration before CPVI can be used as a predictor for AF recurrence.

METHODS

A total of 121 patients without structural heart disease who underwent primary CPVI by a single operator were included in the study (paroxysmal/persistent AF: 77/44). Left atrial diameter was measured by transesophageal echocardiography. Plasma hsCRP concentration was determined by enzyme-linked immunosorbent assay. Based on the follow-up outcomes, patients were divided into two groups, a recurrence group and a nonrecurrence group. AF recurrence was defined as AF or atrial flutter or atrial tachycardia episodes lasting for ≥30 s during regular follow-up (>12 months).

RESULTS

A total of 36 (29.8%) patients (paroxysmal/persistent AF: 19 [24.7%]/17 [38.6%]) had AF recurrence in a mean 23 (range, 12-44) month follow-up period. The plasma hsCRP concentration in the recurrence group was significantly higher than that in the nonrecurrence group for all patients (median [quartile range] 2.22 [1.97] mg/L vs 0.89 [1.30] mg/L, P < 0.001), for patients with paroxysmal AF (2.12 [2.78] mg/L vs 0.84 [1.15] mg/L, P = 0.028), and for those with persistent AF (2.29 [1.08] mg/L vs 0.89 [1.53] mg/L, P = 0.005). Multiple logistic regression analyses showed that the higher level of the plasma hsCRP (P < 0.001) was a significant prognostic predictor of AF recurrence, both for patients with paroxysmal AF (P = 0.012) and those with persistent AF (P = 0.003).

CONCLUSION

Plasma hsCRP concentration before CPVI was associated with AF recurrence after primary CPVI procedure for both paroxysmal and persistent AF patients. Plasma hsCRP concentration could play a role in prediction of AF recurrence after primary CPVI.

Upstream effect for atrial fibrillation: still a dilemma?

Atrial fibrillation is the most common arrhythmia in clinical practice. Ion channel blocking agents are often characterized by limited long-term efficacy and several side effects. In addition, ablative invasive procedures are neither easily accessible nor always efficacious. The "upstream therapy," which includes angiotensin-converting enzyme inhibitors, aldosterone receptor antagonists, statins, glucocorticoids, and ω-3 poly-unsaturated fatty acids, targets arrhythmia substrate, influencing atrial structural and electrical remodeling that play an essential role in atrial fibrillation induction and maintenance. The mechanisms involved and the most important clinical evidence regarding the upstream therapy influence on atrial fibrillation are presented in this review. Some open questions are also proposed.

Atrial fibrillation and inflammation

Atrial fibrillation (AF) is the most common clinical arrhythmia. Recent investigations have suggested that inflammation might have a role in the pathophysiology of AF. In this review, the association between inflammation and AF, and the effects of several agents that have anti-inflammatory actions, such as statins, polyunsaturated fatty acids, corticosteroids and angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, have been investigated.

Understanding heterogeneity in meta-analysis: the role of meta-regression

BACKGROUND

Meta-regression has grown in popularity in recent years, paralleling the increasing numbers of systematic reviews and meta-analysis published in the biomedical literature. However, many clinicians and decision-makers may be unfamiliar with the underlying principles and assumptions made within meta-regression leading to incorrect interpretation of their results.

AIMS

This paper reviews the appropriate use and interpretation of meta-regression in the medical literature, including cautions and caveats to its use.

MATERIALS & METHODS

A literature search of MEDLINE (OVID) from 1966-February 2009 was conducted to identify literature relevant to the topic of heterogeneity and/or meta-regression in systematic reviews and meta-analysis.

RESULTS

Meta-analysis, a statistical method of pooling data from studies included in a systematic review, is often compromised by heterogeneity of its results. This could include clinical, methodological or statistical heterogeneity. Meta-regression, said to be a merging of meta-analytic and linear regression principles, is a more sophisticated tool for exploring heterogeneity. It aims to discern whether a linear relationship exists between an outcome measure and on or more covariates. The associations found in a meta-regression should be considered hypothesis generating and not regarded as proof of causality.

CONCLUSIONS

The current review will enable clinicians and healthcare decision-makers to appropriately interpret the results of meta-regression when used within the constructs of a systematic review, and be able to extend it to their clinical practice.

Atrial fibrillation following cardiac surgery: clinical features and preventative strategies

Atrial fibrillation (AF) is a common complication of cardiac surgery, with an increasing incidence. Post-operative AF results in many complications and increased healthcare resources. Despite substantial interest in the prediction and prevention of post-operative AF, as well as guidelines for the management of this common arrhythmia, there is still some uncertainty about appropriate risk stratification and management. The aim of this review article is to provide an overview of clinical predictive features for the development of AF following cardiac surgery and suitable preventive measures, using both antiarrhythmic and non-antiarrhythmic strategies.

Association between perioperative NSAID use and post-cardiothoracic surgery atrial fibrillation, blood transfusions, and cardiovascular outcomes: a nested cohort study from the AF Suppression Trials (AFIST) I, II and III

BACKGROUND

Nonsteroidal anti-inflammatory drug (NSAID) use may reduce the incidence of post-cardiothoracic surgery (CTS) atrial fibrillation (AF). The cerebrovascular and cardiovascular safety of using NSAIDs for post-CTS AF has not been determined.

OBJECTIVE

To evaluate whether NSAIDs could reduce the incidence of post-CTS atrial fibrillation without increasing patients' risk of stroke or myocardial infarction (MI).

METHODS

Patients (n = 555) undergoing CTS from the Atrial Fibrillation Suppression Trials I, II and III were evaluated in this nested cohort study. Demographic, surgical and medication use characteristics were prospectively collected as part of the AFIST trials. Endpoints included post-CTS atrial fibrillation, stroke, MI and the need for red blood cell transfusion. Multivariable logistic regression was used to control for potential confounders and calculate adjusted odds ratios with 95% confidence intervals.

RESULTS

The population was 67.8 +/- 8.6 years old and 77.1% male with 127 (22.9%) patients receiving an NSAID postoperatively. Overall, 14.6% underwent valve surgery, 6.1% had prior AF, 12.6% had heart failure and 84.0% and 44.1% received postoperative beta-blockade and prophylactic amiodarone. NSAID use was associated with reductions in the adjusted odds of post-CTS atrial fibrillation (0.54 (0.32-0.90)) and the need for RBC transfusions (0.63 (0.41-0.97)). No elevation in the odds of developing stroke (1.10 (0.21-5.66)) or MI (1.70 (0.40-7.10)) was observed.

LIMITATIONS

Patients were not randomized to receive NSAIDs versus a control. We may not have had adequate power to evaluate stoke or MI in this analysis.

CONCLUSIONS

NSAIDs decreased the odds of developing post-CTS atrial fibrillation, further supporting the hypothesis of inflammation as a trigger for post-CTS atrial fibrillation. The need for RBC transfusions was also reduced with NSAID use. We may have been underpowered to evaluate stroke or MI incidence, but the qualitative elevations in these variables suggest more safety data is needed before NSAIDs can be routinely recommended.

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.

Thiazolidinedione use and post-operative atrial fibrillation: a US nested case-control study

BACKGROUND

Previous investigations suggested thiazolidinediones (TZDs) have the ability to suppress inflammation. Since the pathophysiology of atrial fibrillation (AF) after cardiothoracic surgery (CTS) likely involves an inflammatory mechanism, we sought to determine whether preoperative use of TZDs could further reduce the incidence of post-CTS AF in a population treated with beta-blockers and prophylactic amiodarone.

METHODS

All diabetic patients over the age of 50 years, not in atrial arrhythmia prior to surgery, who underwent CTS from the Atrial Fibrillation Suppression Trials I, II and III (AFIST I, II and III) were evaluated in this nested case-control study. Patient demographics, surgical characteristics, medication utilization and the incidence of post-CTS AF (AF > 5 minutes duration) were collected as part of AFIST I, II and III. Multivariate logistic regression was used to calculate adjusted odds ratios with 95% confidence intervals (CIs).

RESULTS

One hundred and eighty-four diabetic patients were enrolled in the three trials. Overall, the study population averaged 66.9 +/- 7.3 years of age, 71.7% were male, 7.1% underwent valve surgery, 4.9% had prior AF, 17.9% had heart failure and 84.2% and 41.8% received postoperative beta-blockade and prophylactic amiodarone, respectively. Forty patients (21.7%) received a preoperative TZD and 144 (78.3%) did not. In total, 66 patients (35.9%) developed post-CTS AF. Upon multivariate logistic regression, the preoperative use of TZDs was found to be associated with a 20% non-statistically significant reduction in post-CTS AF (adjusted odds ratio; 0.80, 95% CI 0.32-1.99; p = 0.63).

LIMITATIONS

Patients were not randomized to receive TZDs or not. We may not have had adequate power to evaluate our post-CTS AF endpoint.

CONCLUSIONS

In a diabetic population treated perioperatively with beta-blocker and amiodarone, adjunctive TZD use was associated with a non-statistically significant reduction in a patient's odds of developing post-CTS AF. Further research is needed to determine whether TZDs, in fact, do not have anti-fibrillatory effects or whether our study was underpowered to detect a statistically significant benefit with TZDs.