Influence of race on atrial fibrillation after cardiac surgery

Dexmedetomidine vs. propofol on arrhythmia in cardiac surgery: a meta-analysis of randomized controlled trials

Background

Dexmedetomidine (DEX) and propofol are popular anesthetics, but it remains unknown whether DEX reduces the incidence of arrhythmias compared with propofol after cardiac surgery.

Methods

We performed a comprehensive search for RCTs (Randomized Controlled Trials) that compared the incidence of arrhythmias between DEX and propofol in adults who had undergone cardiac surgery across three databases (PubMed, Embase, the Cochrane Library), and ClinicalTrials.gov up to October 3, 2023. The primary outcome was ventricular arrhythmias, the secondary outcomes were bradycardia and atrial fibrillation (AF).

Results

Our analysis included 7 RCTs with 1,004 patients (mean age: 64.37, male: 71.11%) undergoing cardiac surgery, and the incidence of in-hospital arrhythmia was 22.01% (ventricular arrhythmias 2.75%, bradycardia 3.33%, AF 18.63%). Perioperative or postoperative use of DEX reduced the incidence of in-hospital ventricular arrhythmias [Odds Ratio (OR) 0.14, 95% Confidence Interval (CI) 0.03-0.66], but increased the risk of in-hospital bradycardia (OR 2.88, 95% CI 1.02-8.17) compared with propofol. The trial sequence analysis verified the adequacy of sample size and robustness of the ventricular arrhythmias and bradycardia. There was no significant reduced incidence of the use of DEX in the incidence of AF (OR 0.69, 95% CI 0.36-1.29). The GRADE assessment indicated a high certainty for ventricular arrhythmias and bradycardia and a moderate certainty for AF.

Conclusions

Our findings suggested the use of DEX reduces in-hospital ventricular arrhythmias but increases bradycardia incidence compared to propofol in adult patients undergoing cardiac surgery. Further studies are needed to assess the impact of dexmedetomidine on atrial fibrillation compared to propofol.

Systematic Review Registration

http://www.crd.york.ac.uk/prospero/ PROSPERO, identifier (CRD42023482193).

Social drivers in atrial fibrillation occurrence, screening, treatment, and outcomes: systematic-narrative hybrid review

The importance of social drivers of health (SDOH) in the occurrence, detection, treatment, and outcome of atrial fibrillation (AF) has attracted increasing attention. Addressing SDOH factors may suggest opportunities to prevent AF and its complications. We aimed to conduct a structured narrative review and summarize current knowledge on the association between race and ethnicity, SDOH, including rural vs. urban habitation, education, income, and neighbourhood, and the risk of AF, its management, and complications. We identified 537 references in PubMed and 473 references in Embase. After removal of duplicates, we screened the abstracts of 975 references, resulting in 113 references that were examined for eligibility. Subsequently, 34 references were excluded leaving 79 references for the review. Evidence of a social gradient in AF incidence and prevelance were conflicting. However, we found substantial evidence indicating social inequities in the detection of AF, access to treatment, and outcomes such as healthcare utilization, bleeding, heart failure, stroke, dementia, work disability, and death. Inequities are reported across various health care systems and constitute a global problem affecting several continents, although data from Africa and South America are lacking. Given the documented social inequities in AF detection, management, and outcomes, there is an urgent need for healthcare systems, policymakers, and society to identify and implement effective interventions that can reduce inequities and improve outcomes in individuals with AF.

Prospective Study of Risk Factors for Postoperative Atrial Fibrillation After Cardiac Surgery

INTRODUCTION

To examine risk factors for new-onset postoperative atrial fibrillation (POAF) after cardiac surgery.

METHODS

Patients enrolled in the Cardiothoracic Surgical Trials Network multicenter, randomized trial of rate control versus rhythm control for POAF were included. Predictors of POAF were determined using multivariable logistic regression.

RESULTS

Among the 2104 patients who were enrolled preoperatively, 695 developed POAF (33.0%). Rates of POAF were 28.1% after isolated coronary artery bypass grafting (CABG), 33.7% after isolated valve repair or replacement, and 47.3% after CABG plus valve repair or replacement. Baseline characteristics associated with an increased risk of POAF identified on multivariable analysis included older age (odds ratio [OR] 1.57; 95% confidence interval [CI] 1.42-1.73, per 10 y), White race or non-Hispanic ethnicity (OR 1.52; CI: 1.11-2.07), history of heart failure (OR 1.55; CI: 1.16-2.08), and history of hypothyroidism (OR 1.42; CI 1.04-1.94). The type of cardiac procedure was associated with an increased risk of POAF with both isolated valve repair or replacement (OR 1.33, CI 1.08-1.64) and combined CABG plus valve repair or replacement (OR 1.64, CI 1.24-2.17) having increased risk of POAF compared to isolated CABG. No preoperative cardiac medication was associated with POAF.

CONCLUSIONS

In this prospective cohort of patients, older age, a history of hypothyroidism, a history of heart failure, and valve repair or replacement, with or without CABG, and White non-Hispanic race were associated with an increased risk of POAF.

Prediction of new onset postoperative atrial fibrillation using a simple Nomogram

BACKGROUND

New onset postoperative atrial fibrillation (POAF) is the most common complication of cardiac surgery, with an incidence ranging from 15 to 50%. This study aimed to develop a new nomogram to predict POAF using preoperative and intraoperative risk factors.

METHODS

We retrospectively analyzed the data of 2108 consecutive adult patients (> 18 years old) who underwent cardiac surgery at our medical institution. The types of surgery included isolated coronary artery bypass grafting, valve surgery, combined valve and coronary artery bypass grafting (CABG), or aortic surgery. Logistic regression or machine learning methods were applied to predict POAF incidence from a subset of 123 parameters. We also developed a simple nomogram based on the strength of the results and compared its predictive ability with that of the CHA2DS2-VASc and POAF scores currently used in clinical practice.

RESULTS

POAF was observed in 414 hospitalized patients. Logistic regression provided the highest area under the receiver operating characteristic curve (ROC) in the validation cohort. A simple bedside tool comprising three variables (age, left atrial diameter, and surgery type) was established, which had a discriminative ability with a ROC of 0.726 (95% CI 0.693-0.759) and 0.727 (95% CI 0.676-0.778) in derivation and validation subsets respectively. The calibration curve of the new model was relatively well-fit (p = 0.502).

CONCLUSIONS

Logistic regression performed better than machine learning in predicting POAF. We developed a nomogram that may assist clinicians in identifying individuals who are prone to POAF.

Association of LDL to HDL ratio with new-onset atrial fibrillation after on-pump coronary artery bypass graft surgery

OBJECTIVE

This study aims to analyze the association between preoperative LDL/HDL ratio and new-onset atrial fibrillation (AF) after on-pump coronary artery bypass grafting (on-pump CABG), evaluate the clinic value of preoperative LDL/HDL ratio to identify postoperative rhythm.

METHODS

A retrospective study of consecutive patients (n = 2052) who underwent on-pump CABG at TEDA International Cardiovascular Hospital (Tianjin, China), from June 1, 2020, to December 30, 2021, was conducted. The association between preoperative LDL/HDL and new-onset POAF was analyzed by Lowess curve and univariate logistic regression. The receiver operating characteristic curve (ROC) and area under the curve (AUC) were used to evaluate the identification capacity of preoperative LDL/HDL level for new-onset POAF.

RESULTS

In studied populations, the incidence of new-onset POAF was about 29.24%. The lowess curve showed that the association between preoperative LDL/HDL ratio and POAF after on-pump CABG was similar to a linear relationship. With the increasement of preoperative LDL/HDL ratio, the incidence of POAF increased simultaneously. ROC analysis showed that preoperative LDL/HDL ratio could identify postoperative arrhythmia after on-pump CABG (AUC = 0.569,95% CI = 0.529-0.608, P = 0.006) among female patients, the best preoperative LDL/HDL ratio cutoff of 2.11, which was considered a predictive factor of incident POAF, showed a sensitivity of 83.60% (95% CI = 0.775-0.886) and a specificity of 30.02% (95% CI = 0.257-0.346).

CONCLUSION

Preoperative LDL/HDL ratio is associated with new-onset POAF, but there is a difference in different sex. Preoperative LDL/HDL level can help to identify postoperative rhythm in females.

Influence of Dexmedetomidine on Post-operative Atrial Fibrillation After Cardiac Surgery: A Meta-Analysis of Randomized Controlled Trials

Background: Previous clinical studies and meta-analysis evaluating the influence of dexmedetomidine on postoperative atrial fibrillation showed inconsistent results. We performed an updated meta-analysis to evaluate the influence of dexmedetomidine on incidence of postoperative atrial fibrillation after cardiac surgery.

Methods: Randomized controlled trials that evaluated the potential influence of dexmedetomidine on the incidence of atrial fibrillation after cardiac surgery were obtained by search of PubMed, Embase, and Cochrane's Library databases from inception to April 12, 2021. A random-effects model incorporating the potential publication bias was used to pool the results. Influences of patient or study characteristics on the efficacy of dexmedetomidine on atrial fibrillation after cardiac surgery were evaluated by meta-regression and subgroup analyses.

Results: Fifteen studies with 2,733 patients were included. Pooled results showed that dexmedetomidine significantly reduced the incidence of atrial fibrillation compared to control (OR: 0.72, 95% CI: 0.55–0.94, p = 0.02) with mild heterogeneity (I² = 26%). Subgroup analysis showed that dexmedetomidine significantly reduced the incidence of atrial fibrillation in studies from Asian countries (OR: 0.41, 95% CI: 0.26–0.66, p < 0.001), but not in those from non-Asian countries (OR: 0.89, 95% CI: 0.71–1.10, p = 0.27; p for subgroup difference = 0.004). Meta-regression analysis showed that the mean age and proportion of male patients may modify the influence of dexmedetomidine on POAF (coefficient = 0.028 and 0.021, respectively, both p < 0.05). Subgroup analysis further showed that Dex was associated with reduced risk of atrial fibrillation after cardiac surgery in studies with younger patients (mean age ≤ 61 years, OR = 0.44, 95% CI: 0.28–0.69, p = 0.004) and smaller proportion of males (≤74%, OR = 0.55, 95% CI: 0.36–0.83, p = 0.005), but not in studies with older patients or larger proportion of males (p for subgroup difference = 0.02 and 0.04).

Conclusions: Current evidence supports that perioperative administration of dexmedetomidine may reduce the risk of incidental atrial fibrillation after cardiac surgery, particularly in Asians.

Predicting atrial fibrillation after cardiac surgery using a simplified risk index

BACKGROUND

Postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery and can lead to increased risk of postoperative adverse events. However, atrial fibrillation and postoperative adverse events are preventable. In this study, a risk index was developed to predict atrial fibrillation after cardiac surgery.

METHODS

A prospective cohort study of 405 patients who had undergone adult cardiac surgery from 2015 September to 2016 August at Heart Institute of HCMC and Cho Ray Hospital were obtained. In order to predict POAF, a logistic regression model was developed, and a risk score was derived and validated by bootstrap.

RESULTS

In our study, 98 patients developed POAF (24.2%). The risk score included three significant risk factors (age ≥ 60, left atrial diameter > 41 mm, Coronary Artery Bypass Graft with concomitant mitral valve replacement or repair) that were consistent with other reports. Each of these risk factors was assigned one point. The total risk score ranges from 0 to 3 (AUC = 0.69, 95% CI: 0.63-0.75) with the best cutoff point at 1. According to this scoring system, the incidences of POAF in patients associated with each score of 0, 1, 2, and 3 were 8.6%, 30.1%, 40.8%, and 58.3% respectively. Bootstrapping with 5000 samples confirmed the final model provided was consistent with predictions.

CONCLUSIONS

We developed and validated a simple risk score based on clinical variables that can be obtained before surgery in order to accurately predict the risk of POAF in patients undergoing cardiac surgery.

NT -pro BNP as a Mediator of the Racial Difference in Incident Atrial Fibrillation and Heart Failure

Background

Blacks harbor more cardiovascular risk factors than whites, but experience less atrial fibrillation (AF). Conversely, whites may have a lower risk of heart failure (CHF). N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) levels are higher in whites, predict incident AF, and have diuretic effects in the setting of increased ventricular diastolic pressures, potentially providing a unifying explanation for these racial differences.

Methods and Results

We used data from the CHS (Cardiovascular Health Study) to determine the degree to which baseline NT‐proBNP levels mediate the relationships between race and incident AF and CHF by comparing beta estimates between models with and without NT‐proBNP. The ARIC (Atherosclerosis Risk in Communities) study was used to assess reproducibility. Among 4731 CHS (770 black) and 12 418 ARIC (3091 black) participants, there were 1277 and 1253 incident AF events, respectively. Whites had higher baseline NT‐proBNP (CHS: 40% higher than blacks; 95% CI, 29–53; ARIC: 39% higher; 95% CI, 33–46) and had a greater risk of incident AF compared with blacks (CHS: adjusted hazard ratio, 1.60; 95% CI, 1.31–1.93; ARIC: hazard ratio, 1.93; 95% CI, 1.57–2.27). NT‐proBNP levels explained a significant proportion of the racial difference in AF risk (CHS: 36.2%; 95% CI, 23.2–69.2%; ARIC: 24.6%; 95% CI, 14.8–39.6%). Contrary to our hypothesis, given an increased risk of CHF among whites in CHS (adjusted hazard ratio, 1.20; 95% CI, 1.05–1.47) and the absence of a significant association between race and CHF in ARIC (adjusted hazard ratio, 1.07; 95% CI, 0.94–1.23), CHF‐related mediation analyses were not performed.

Conclusions

A substantial portion of the relationship between race and AF was statistically explained by baseline NT‐proBNP levels. No consistent relationship between race and CHF was observed.

See Editorial by Richards

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.

Risk of new-onset atrial fibrillation after drug-eluting stent implantation in patients with stable coronary artery disease

BACKGROUND

New-onset atrial fibrillation (NOAF) is associated with adverse outcomes in patients with coronary artery disease (CAD). Although newer generation drug-eluting stents (NG-DESs) are more beneficial than bare-metal stents (BMSs) in reducing the risk of in-stent restenosis and revascularization, whether NG-DES implantation in patients with stable CAD reduces NOAF risk compared with BMS implantation remains unknown.

METHODS

This population-based cohort study was conducted using data from Taiwan's National Health Insurance Research Database. Propensity score matching was used to select 18,423 pairs of patients with stable CAD receiving NG-DES implantation and BMS implantation with similar baseline characteristics for evaluation. A competing risk model was used to evaluate the risk of NOAF between the NG-DES and BMS groups in which death was considered a competing risk.

RESULTS

After adjustment for patients' clinical variables, the use of NG-DESs was associated with a decreased risk of NOAF at 1-year follow-up (adjusted subdistribution hazard ratio [SHR] = 0.79, 95% confidence interval [CI] = 0.68-0.93, P = 0.005) compared with the use of BMSs. Similar results indicated that NG-DESs were beneficial for reducing the risk of NOAF (adjusted SHR = 0.81, 95% CI = 0.67-0.97, P = 0.020) in patients with a CHA₂DS₂-VASc score of ≥2. These findings were also consistent with those for patients who received dual antiplatelet therapy for an undefined duration of >1 month following stent implantation.

CONCLUSIONS

Our findings suggest that NG-DESs might reduce the risk of NOAF in patients with stable CAD.

Postoperative Atrial Fibrillation Among Patients Undergoing Isolated Coronary Artery Bypass Grafting

Introduction Postoperative atrial fibrillation (AF) is the commonest of all the known cardiac arrhythmias after cardiac surgery. The postoperative AF has both short- and long-term adverse impacts on patients, like prolonged intensive care unit (ICU) stay, increased frequency of reoperations, myocardial infarction, increased use of inotropes, and intra-aortic balloon pump (IABP). There is a paucity of data regarding the postoperative AF after isolated coronary artery bypass grafting (CABG) and its risk factors in our geographic location. Therefore, the aim of this study was to determine the frequency of postoperative atrial fibrillation among patients undergoing isolated CABG at a tertiary care hospital of Karachi, Pakistan. Methods This prospective observational study was conducted on 163 consecutively selected patients undergoing first time isolated CABG at the Department of Cardiothoracic Surgery, Aga Khan University Hospital, Karachi. Patients with redo-sternotomy, preoperative atrial fibrillation and with other cardiac pathology were excluded from the study. Postoperative AF was defined in the patients with postoperative 12-lead electrocardiographic (ECG) finding of absence of P waves, replaced by unorganized electrical activity and irregular R-R intervals. Data analysis was carried out using IBM SPSS Statistics for Windows, Version 21.0 (IBM Corp., Armonk, NY, USA). Results A total of 163 patients were enrolled with the mean age of 58.66 ± 9.77 years ranging between 40 and 85 years with male predominance of 81% (132). The most common comorbidity was hypertension in about 68.1% (111), followed by diabetes mellitus in 54.6% (89) patients. Postoperative AF was observed in 42 (25.8%) patients. Most of the patients who developed postoperative AF, were overweight with mean body mass index (BMI) of 27.04 ± 4.85 kg/m2, 76.2% (32) had a history of hypertension, diabetes mellitus was associated with 33.3% (14) patients with postoperative AF and 50.0% (21) of them were smokers. Distribution of coronary artery disease in patients with postoperative AF was observed as three vessels coronary artery disease (3VCAD) in 83.3% (35), two-vessel coronary artery disease (2VCAD) was present in 7.1% (three), and rest of 9.5% (four) patients had single-vessel coronary artery disease (SVCAD). Conclusion The frequency of postoperative atrial fibrillation in our study was found to be 25.9% which is comparable to world literature. An important finding that comes through this study is a younger population undergoing CABG, which raises the possibility of early manifestation of ischemic heart disease in our region. This, however, needs further investigation. We were unable to point out the factors predictive of postoperative AF; studies with larger sample size would help in that regard.

Factors associated with postoperative atrial fibrillation and other adverse events after cardiac surgery

OBJECTIVE

The study objective was to evaluate the impact of various surgical characteristics and practices on the risk of postoperative atrial fibrillation and other adverse outcomes after cardiac surgery.

METHODS

By using the prospectively collected data of patients who underwent cardiac surgery in 28 centers across the United States, Italy, and Argentina, the details of surgery characteristics were collected for each patient and the outcomes, including postoperative atrial fibrillation, major adverse cardiovascular events, and mortality. These were evaluated via multivariable-adjusted models.

RESULTS

In 1462 patients, a total of 460 cases of postoperative atrial fibrillation, 33 major adverse cardiovascular events, 23 cases of 30-day mortality, and 46 cases of 1-year mortality occurred. We found that type of surgery and cardiopulmonary bypass use predicted the occurrence of postoperative atrial fibrillation. Compared with coronary artery bypass grafting alone, there was a higher risk of postoperative atrial fibrillation with valvular surgery alone (odds ratio, 1.4; 95% confidence interval, 1.1-1.9), and the risk was even higher with concomitant valvular and coronary artery bypass grafting surgery (odds ratio, 1.8; 95% confidence interval, 1.2-2.7). Compared with no bypass, use of cardiopulmonary bypass was associated with higher risk of postoperative atrial fibrillation (odds ratio, 2.4; 95% confidence interval, 1.7-3.5), but there were significant age and sex differences of the impact of bypass use among patients undergoing coronary artery bypass grafting (P for interaction = .04). In addition, compared with spontaneous return of rhythm, ventricular pacing was associated with a higher risk of major adverse cardiovascular events (odds ratio, 5.0; 95% confidence interval, 1.4-18), whereas concomitant coronary artery bypass grafting and valvular surgery was associated with a higher risk of 30-day mortality (hazard ratio, 4.3; 95% confidence interval, 1.2-14) compared with coronary artery bypass grafting alone. Occurrence of postoperative atrial fibrillation was associated with greater length of stay and 1-year mortality (hazard ratio, 2.2; 95% confidence interval, 1.2-3.9).

CONCLUSIONS

In this multicenter trial, we identified specific adverse outcomes that are associated with concomitant valvular and coronary artery bypass graft surgery, cardiopulmonary bypass, ventricular pacing, and occurrence of postoperative atrial fibrillation.

Racial Disparities in Elderly Patients Receiving Lumbar Spinal Stenosis Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To evaluate for racial disparities in elderly patients having undergone lumbar spinal stenosis surgery.

METHODS

The US Medicare Provider Analysis and Review database (records from 2005 to 2011) was used to identify patients over the age of 65 years, diagnosed with lumbar spinal stenosis, and having undergone lumbar laminectomy or fusion surgery. Blacks were compared to Whites in both unmatched and propensity score-matched populations. The data was analyzed with univariate (χ² and Wilcoxon rank sum tests for unmatched comparison, and McNemar exact and signed rank sum tests for matched comparison) and multivariate models.

RESULTS

Query of the data resulted in a study sample of 12 807 patients; 514 (4.0%) were identified as Black and 12 293 (96%) as White. Blacks were less likely to be discharged home (42.4% vs 58.9%, P < .0001) and had lower repeat operation rates (6.81% vs 11.5%, P = .0009); both remained significant in the propensity score-matched comparison. Finally, Blacks experienced more postoperative complications, higher median Medicare costs, but lower out-of-pocket expenses (P = .0113). Blacks had higher rates of diabetes (33.7% vs 21.5%, P < .0001) and obesity (9.92% vs 6.85%, P = .0074), when compared to Whites, but these comorbidities did not significantly affect odds of 30-day complications.

CONCLUSIONS

Black patients having undergone lumbar spinal stenosis surgery were more likely to have received fusion at initial operation, had shorter pre- and postoperative follow-up intervals and displayed variances in discharge disposition. Reasons for these differences are not entirely understood; however, educational and socioeconomic factors and possibly ethnic/cultural biases may have contributed. Racial disparities in health care continue to be identified and should be further explored in order to eliminate them.

Perioperative Inotrope Therapy and Atrial Fibrillation Following Coronary Artery Bypass Graft Surgery: Evidence of a Racial Disparity

BACKGROUND AND OBJECTIVE

Following coronary artery bypass graft (CABG) surgery, mortality rates are significantly higher among black patients who experience postoperative atrial fibrillation (POAF). Perioperative inotropic therapy (PINOT) was associated with POAF in previous reports, but the extent to which race influences this association is unknown. In the present study, the relationship between PINOT, race, and POAF was examined in patients undergoing CABG surgery.

METHODS AND SETTING

Clinical records were examined from a prospectively maintained cohort of 11,855 patients (median age 64 yrs; 70% male; 16% black) undergoing primary isolated CABG at a large cardiovascular institute in the southeastern region of the United States. Relative risk (RR) and 95% confidence intervals (CIs) were computed using log-binomial regression.

MAIN RESULTS

The association between PINOT and POAF was significantly increased among black patients (adjusted RR 1.7, CI 1.4-2.0) compared with white patients (adjusted RR 1.3, CI 1.2-1.4) (p_interaction  = 0.013).

CONCLUSIONS

These findings suggest that PINOT may be disproportionately associated with POAF among black patients undergoing CABG surgery. Additional studies are needed to examine further the potential underlying mechanisms of this association.

Circulating Biomarkers Predictive of Postoperative Atrial Fibrillation

Postoperative atrial fibrillation (PoAF), a common complication of cardiac surgery, contributes significantly to morbidity, mortality, and increasing healthcare costs. Despite advances in surgical and medical management, the overall incidence of PoAF has not changed significantly, partly because of the limited understanding of mechanisms underlying acute surgery-related factors, such as myocardial injury, inflammation, sympathetic activation, and oxidative stress, which play an important role in the initiation of PoAF, whereas a preexisting atrial substrate appears to be more important in the maintenance of this dysrhythmia. Thus, in a majority of patients, PoAF becomes a manifestation of an underlying arrhythmogenic substrate that is unmasked after acute surgical stress. As such, the ability to identify which patients have this proarrhythmic substrate and are, therefore, at high risk for developing AF postoperatively, is important for the improved selection for prophylactic interventions, closer monitoring for complications, and establishing the probability of AF in the long term. This review highlights the role of the underlying substrate in promoting PoAF, proposed mechanisms, and the potential role of serum biomarkers to identify patients at risk for PoAF.

GRK5 Polymorphisms and Postoperative Atrial Fibrillation following Coronary Artery Bypass Graft Surgery

Postoperative atrial fibrillation (POAF) is a serious yet common complication after coronary artery bypass grafting (CABG) surgery. Previous study have identified multiple genetic susceptibility loci for POAF susceptibility after CABG, although some studies are under-powered. However, none of these studies have been conducted among Asians. In current study, we aim to systematically evaluated the previous positive findings for POAF susceptibility after CABG among Chinese population, using a large population-based, two-stage, case-cohort study. From a discovery cohort of 1,348 patients, a total of nine independent loci were evaluated. Six significant SNPs were then assessed in a separately collected validation cohort of 2,000 patients. After adjustment for clinical predictors of POAF, two variants in GRK5 gene (rs4752292, and rs11198893) were replicated with significance were replicated in the validation cohort. The ORs for each additional copy of minor allele were 1.32 (95% CI: 1.15-1.50, P = 5.82 × 10(-5)) and 1.47 (95% CI: 1.28-1.69, P = 1.16 × 10(-7)), respectively. In this two-stage independently collected cardiac surgery cohorts, genetic variations in the GRK5 gene are independently associated with POAF risk in patients who undergo CABG surgery in Asians.

Postoperative atrial fibrillation in non-cardiac and cardiac surgery: an overview

Postoperative atrial fibrillation (POAF) is the most common perioperative cardiac arrhythmia. A major risk factor for POAF is advanced age, both in non-cardiac and cardiac surgery. Following non-cardiac surgery, it is important to correct reversible conditions such as electrolytes imbalances to prevent the occurrence of POAF. Management of POAF consists of rate control and therapeutic anticoagulation if POAF persists for > 48 h and CHADS2 score > 2. After cardiac surgery, POAF affects a larger amount of patients. In addition to age, valve surgery carries the greatest risk for new AF. Rate control is the mainstay therapy in these patients. Prediction, prevention, and management of POAF should be further studied.

Differential Outcomes by Race and Ethnicity in Patients with Coronary Heart Disease: A Contemporary Review

Coronary heart disease (CHD) is a leading cause of death for people of most ethnicities in the USA. However, several racial and ethnic minority groups are disproportionately burdened by CHD and experience higher mortality rates and rehospitalization rates compared with whites. Contemporary CHD research has been dedicated in part to broadening our understanding of the root causes of racial and ethnic disparities in CHD outcomes. Several factors contribute, including socioeconomic and comorbid conditions. These factors may be amenable to change, and targets for initiatives to reduce disparities and improve CHD outcomes. In this article, we review the recently published research related to the distribution and determinants of racial and ethnic differences in CHD outcomes in the USA.

Anticoagulation strategies for the management of postoperative atrial fibrillation

Patients undergoing thoracic and cardiac procedures are at the highest risk for postoperative atrial fibrillation (POAF). POAF is associated with poor short-term and long-term outcomes, including high rates of early and late stroke, and late mortality. Patients with POAF that persists for longer than 48 hours should be anticoagulated on warfarin. Three new oral anticoagulants are available for the treatment of nonvalvular atrial fibrillation and have been found to be as efficacious or superior to warfarin in the prevention of stroke in high-risk patients, with similar to lower rates of major bleeding, and lower rates of intracranial hemorrhage.

The impact of race and postoperative atrial fibrillation on operative mortality after elective coronary artery bypass grafting

OBJECTIVE

Black patients are less likely to develop postoperative atrial fibrillation (POAF) following coronary artery bypass grafting (CABG) than whites. However, the influence of race and POAF on operative mortality has not been examined. The objective of this study was to determine the influence of race and POAF on operative mortality after CABG.

METHODS

Patients undergoing elective CABG between 1992 and 2011 were included. Operative mortality was compared between patients with and those without new-onset POAF by race. Relative risk (RR) and 95% confidence intervals (CI) were computed using Poisson (robust variance estimates) and log-binomial regression models.

RESULTS

A total of 1215 (23%) patients developed POAF (white n=1060; black n=155) following CABG (N=5387). Operative mortality differed by POAF status within race category (white POAF: adjusted RR=1.4, 95% CI=0.86-2.2; black POAF: adjusted RR=5.0, 95% CI=1.9-13; Pinteraction=0.0016). Black POAF patients had a 2-fold increased risk of operative death compared with white POAF patients (Padjusted=0.052).

CONCLUSION

POAF was observed to be a stronger predictor of operative mortality in black compared with white patients undergoing elective CABG.

Ethnic differences in atrial fibrillation identified using implanted cardiac devices

INTRODUCTION

Atrial fibrillation (AF) is suggested to be less common among black and Asian individuals, which could reflect bias in symptom reporting and access to care. In the Asymptomatic AF and Stroke Evaluation in Pacemaker Patients and the AF Reduction Atrial Pacing Trial (ASSERT), patients with hypertension but no history of AF had AF recorded via an implanted pacemaker or defibrillator, thus allowing both symptomatic and asymptomatic AF incidence to be determined without ascertainment bias.

METHODS AND RESULTS

The ASSERT enrolled 2,580 patients in 23 countries in North America, Europe, and Asia. AF was defined as device-recorded AF episodes >190/min, lasting either for >6 minutes or >6 hours in duration. All ethnic groups with >50 patients were enrolled. Ethnic groups studied include Europeans (n = 1900), black Africans (n = 73), Chinese (n = 89), and Japanese (n = 105) patients. Compared to Europeans, black Africans had more risk factors for AF such as heart failure (27.8 vs 14.6%) and diabetes (41.7 vs 26.3%). At 2.5 years follow-up, all 3 non-European races had a lower incidence of AF (8.3%, 10.1%, and 9.5% vs 18.0%, respectively, for AF>6 minutes, P < 0.006). When adjusted for baseline difference, Chinese had a lower incidence of AF > 6 minutes (P < 0.007), and Japanese and black Africans had a lower incidence of AF > 6 hours (P < 0.04 and P = 0.057, respectively).

CONCLUSIONS

Black Africans, Chinese, and Japanese had lower incidence of AF compared to Europeans. In the case of black Africans, this is despite an increased prevalence of AF risk factors.

Incidence, predictors, and outcomes associated with postoperative atrial fibrillation after major noncardiac surgery

BACKGROUND

Although major noncardiac surgery is common, few large-scale studies have examined the incidence and consequences of post-operative atrial fibrillation (POAF) in this population. We sought to define the incidence of POAF and its impact on outcomes after major noncardiac surgery.

METHODS

Using administrative data, we retrospectively reviewed the hospital course of adults who underwent major noncardiac surgery at 375 US hospitals over a 1-year period. Clinically significant POAF was defined as atrial fibrillation occurring during hospitalization that necessitated therapy.

RESULTS

Of 370,447 patients, 10,957 (3.0%) developed clinically significant POAF while hospitalized. Of patients with POAF, 7,355 (67%) appeared to have pre-existing atrial fibrillation and 3,602 (33%) had newly diagnosed atrial fibrillation. Black patients had a lower risk of POAF (adjusted odds ratio, 0.53; 95% CI, 0.48-0.59; P < .001). Patients with POAF had higher mortality (adjusted odds ratio, 1.72; 95% CI, 1.59-1.86; P < .001), markedly longer length of stay (adjusted relative difference, +24.0%; 95% CI, +21.5% to +26.5%; P < .001), and higher costs (adjusted difference, +$4,177; 95% CI, +$3,764 to +$4,590; P < .001). These findings did not differ by whether POAF was a recurrence of pre-existing atrial fibrillation, or a new diagnosis.

CONCLUSION

POAF following noncardiac surgery is not uncommon and is associated with increased mortality and cost. Our study identifies risk factors for POAF, which appear to include race. Strategies are needed to not only prevent new POAF, but also improve management of patients with pre-existing atrial fibrillation.

Postoperative Atrial Fibrillation: Year 2011 Review of Predictive and Preventative Factors of Atrial Fibrillation Post Cardiac Surgery

Background: Post cardiac surgery atrial fibrillation is common after cardiac surgery. Despite the advances in medical and surgical treatment, its incidence remains high and unchanged for decades. The aim of this review was to summarize studies published in 2011 on identifying factors, prevention strategies, treatment and effect of post operative atrial fibrillation (POAF) on the outcome after cardiac surgery. Methods: A review was performed on Medline, Embase and Chocrane on all of the English-language, peer-reviewed published clinical studies on POAF; studies investigating the mechanism of developing POAF, prevention, treatment and outcome were all included and analyzed. Case reports, studies on persistent/preoperative atrial fibrillation (AF), POAF after cardiac transplant, congenital cases and nonclinical studies were all excluded. We have also valuated these studies based on the type of the study, their originality, impact factor of the journal and their limitations. Results: Overall 62 studies were reviewed and analyzed; 26 on POAF predictive factors, 31 on preventative strategies and 6 on the outcome of POAF. Of these studies only two were original and the remaining were either performed in AF in general population (n=10) or had been studied and reported several times before in cardiac surgery (n=50). The average impact factor of the journals that POAF was published in was only 2.8 ranging between 0.5 and 14.5. Conclusion: Post cardiac surgery atrial fibrillation is a multi-factorial and complex condition. Cardiac surgery may be a risk factor for developing POAF in patients already susceptible to this condition and may not be a complication of cardiac surgery. Future studies should mainly focus on histological changes in the conductive tissue of atrium and related treatment strategies rather than predictive factors of POAF and more funding should be made available to study this condition from new and entirely different perspectives.

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

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