Effect of race on the frequency of postoperative atrial fibrillation following coronary artery bypass grafting

Atrial fibrillation prevalence and management patterns in a Middle Eastern community in the United States: A retrospective study

Atrial fibrillation (AF) is the most common sustained cardiac dysrhythmia in the United States, and its prevalence is expected to increase along with associated morbidity and economic burden. Prior research has demonstrated differing prevalence patterns of AF between racial and ethnic groups, with lower rates identified in Black patients. However, to date there have been no studies on AF prevalence in people of Middle Eastern descent within the United States. This retrospective cross-sectional study aimed to characterize prevalence patterns of AF in Middle Eastern patients in Southeast Michigan relative to White and Black patients. The final cohort included 919,454 patients with a median (IQR) age of 53 (33) years (515,902 [56 %] female). The overall prevalence of AF was approximately 5 %. We observed a lower prevalence of AF in Middle Eastern (2.8 %) and Black patients (3.4 %) than in White patients (6.5 %). Middle Eastern patients with AF were younger with a lower prevalence of cardiovascular risk factors than White patients. Multivariable analysis showed that Middle Eastern (OR 0.75; 95 % CI 0.71-0.80; P < 0.001) and Black racial identity (OR 0.48; 95 % CI 9.47-0.49; P < 0.001) were associated with a lower odds of AF, even after adjustment for traditional risk factors.

Anticoagulation Control in Different Ethnic Groups Receiving Vitamin K Antagonist for Stroke Prevention in Atrial Fibrillation

Vitamin K antagonist such as warfarin reduces the risk of stroke in atrial fibrillation (AF) patients. Since warfarin has a narrow therapeutic index, its administration needs to be regularly monitored to avoid any adverse clinical outcomes such as stroke and bleeding. The quality of anticoagulation control with warfarin therapy can be measured by using time in therapeutic range (TTR). This review focuses on the prevalence of AF, quality of anticoagulation control (TTR) and adverse clinical outcome in AF patients within different ethnic groups receiving warfarin therapy for stroke prevention. A literature search was conducted in Embase and PubMed using keywords of “prevalence,” “atrial fibrillation,” “stroke prevention,” “oral anticoagulants,” “warfarin,” “ethnicities,” “race” “time in therapeutic range,” “adverse clinical outcome,” “stroke, bleeding.” Articles published by 1st February 2020 were included. Forty-one studies were included in the final review consisting of AF prevalence (n = 14 studies), time in therapeutic range (n = 18 studies), adverse clinical outcome (n = 9 studies) within different ethnic groups. Findings indicate that higher prevalence of AF but better anticoagulation control among the Whites as compared to other ethnicities. Of note, non-whites had higher risk of strokes and bleeding outcomes while on warfarin therapy. Addressing disparities in prevention and healthcare resource allocation could potentially improve AF-related outcomes in minorities.

Racial difference in atrial size and extracellular matrix homeostatic response to hypertension: Is this a potential mechanism of reduced atrial fibrillation in African Americans?

BACKGROUND

Atrial fibrillation (AF) is less common in African Americans (AA) than Caucasians (C) despite a higher prevalence of risk factors such as hypertension (HTN).

OBJECTIVE

Test the hypothesis that differences in extracellular matrix (ECM) between AA and C in response to HTN might attenuate atrial enlargement and alter myocardial fibrosis.

METHODS

ECM-related plasma biomarkers and echo data were collected from 326 C and 129 AA subjects with no history of AF, stratified by the presence of HTN, HTN with left ventricular hypertrophy (LVH), or HTN with LVH and heart failure with preserved ejection fraction (HFpEF).

RESULTS

Left atrial size was significantly smaller and the extent of enlargement in the presence of HTN was less in AA despite similar ventricular relative wall thickness, echocardiographic measures of diastolic function, and 6 minute-walk-test. AA had significantly lower levels of collagen I telopeptide and higher levels of collagen I propeptide among all strata, suggesting unique collagen homeostasis. Matrix metalloproteinases (MMP) and tissue inhibitors of matrix metalloproteinase (TIMP) showed a distinctive response to HTN in AA, with significantly lower levels of MMP-2, MMP-3, and MMP-8 in AA with HTN and significantly lower levels of TIMP-1 and TIMP-3 in AA with HTN and AA with LVH. AA had significantly lower levels of NT-pro-BNP in all strata.

CONCLUSION

This cross-sectional study demonstrates a racial disparity in ECM blood biomarkers and atrial remodeling in response to HTN and in the development of LVH and HFpEF that may partly help explain the decreased risk of AF in AA.

Comparison of Anticoagulants for Postoperative Atrial Fibrillation After Coronary Artery Bypass Grafting: A Pilot Study

BACKGROUND

Direct-acting oral anticoagulants are indicated for the treatment of nonvalvular atrial fibrillation, but their use in patients after undergoing cardiac surgery is poorly defined despite a high prevalence of postoperative atrial fibrillation in this population.

METHODS

Patients diagnosed with postoperative atrial fibrillation were prospectively randomized to warfarin or apixaban. Safety, efficacy, and economic outcomes were evaluated until their 4- to 6-week postoperative appointment.

RESULTS

While this pilot study was not powered to determine a difference in safety or efficacy, adverse event rates were similar to the published literature. It was noted that a patient's course of therapy when utilizing apixaban was significantly less costly than warfarin when including medication, bridging, and laboratory expenses.

CONCLUSION

Apixaban and warfarin both appeared to be safe and effective for anticoagulation throughout the duration of this pilot study in treating postoperative atrial fibrillation after coronary artery bypass grafting. Apixaban was associated with significantly less expense when bridging and monitoring costs were included in addition to medication expense.

Racial Differences in Atrial Fibrillation Epidemiology, Management, and Outcomes

PURPOSE OF THE REVIEW

Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice and is associated with significant morbidity and healthcare cost. Most of the AF studies have predominantly included white population, with under-representation of minority population. In this review, we analyze the racial differences in epidemiology, disease awareness, risk factors, genetics, treatments, and outcomes of AF.

RECENT FINDINGS

African Americans have a higher prevalence of established AF risk factors but lower incidence and prevalence of AF than non-Hispanic whites. There is also a significant racial and ethnic differences in the prevalence of AF-related symptoms and the detection and awareness of AF. Non-white patients are afforded decreased use of rhythm control treatment strategies and anticoagulation both with warfarin and NOACs for stroke prevention. They are less likely to receive catheter ablation (CA) of AF, compared with non-Hispanic whites. AF in the minority racial and ethnic groups carries increased morbidity and mortality compared with white groups, especially in the black individuals with AF, who have been shown to have a lower QoL compared with their white or Hispanic counterparts. Minorities experience stroke more frequently than the whites which is usually more severe and disabling. There are significant racial differences in AF risk factors, manifestations, management, and outcomes. Recognition of these differences will aid in developing better preventive and treatment strategies for AF to decrease morbidity and mortality. In addition, this knowledge will enhance our understanding regarding the pathophysiology of AF including genetic predisposition.

Epidemiology of atrial fibrillation

BACKGROUND

The most common type of arrhythmia in the USA and in European countries is atrial fibrillation (AF). The prevalence of AF is increasing worldwide with advances in technology, better prediction methods and increased awareness among healthcare professionals and patients.

METHODS

This article summarises the literature on the epidemiology of AF worldwide according to continents, age and ethnicity/race, and also includes the prevalence of AF in stroke patients.

RESULTS

In Australia, Europe and the USA, the current estimated prevalence of AF is about between 1% and 4%, with lower prevalence evident in Asia (0.49%-1.9%). AF prevalence is highest among Whites. In Western Europe, Australia and North America 70% of people with AF are aged >65 years, whereas the average age of AF patients in other geographical regions is often lower.

CONCLUSIONS

Although the prevalence of AF worldwide is increasing steadily, large variation can be seen between studies and countries. Further epidemiological studies should be undertaken globally, especially in Asian and African countries so that a better and more accurate picture of the incidence and prevalence of AF can be captured, to enable stroke prevention strategies to be appropriately implemented to prevent or reduce the risk of stroke, the most severe consequence of AF.

Atrial Fibrillation: Epidemiology, Pathophysiology, and Clinical Outcomes

The past 3 decades have been characterized by an exponential growth in knowledge and advances in the clinical treatment of atrial fibrillation (AF). It is now known that AF genesis requires a vulnerable atrial substrate and that the formation and composition of this substrate may vary depending on comorbid conditions, genetics, sex, and other factors. Population-based studies have identified numerous factors that modify the atrial substrate and increase AF susceptibility. To date, genetic studies have reported 17 independent signals for AF at 14 genomic regions. Studies have established that advanced age, male sex, and European ancestry are prominent AF risk factors. Other modifiable risk factors include sedentary lifestyle, smoking, obesity, diabetes mellitus, obstructive sleep apnea, and elevated blood pressure predispose to AF, and each factor has been shown to induce structural and electric remodeling of the atria. Both heart failure and myocardial infarction increase risk of AF and vice versa creating a feed-forward loop that increases mortality. Other cardiovascular outcomes attributed to AF, including stroke and thromboembolism, are well established, and epidemiology studies have championed therapeutics that mitigate these adverse outcomes. However, the role of anticoagulation for preventing dementia attributed to AF is less established. Our review is a comprehensive examination of the epidemiological data associating unmodifiable and modifiable risk factors for AF and of the pathophysiological evidence supporting the mechanistic link between each risk factor and AF genesis. Our review also critically examines the epidemiological data on clinical outcomes attributed to AF and summarizes current evidence linking each outcome with AF.

Preoperative Antihypertensive Medication in Relation to Postoperative Atrial Fibrillation in Patients Undergoing Cardiac Surgery: A Meta-Analysis

Background. We undertake a systematic review and meta-analysis to evaluate the effect of preoperative hypertension and preoperative antihypertensive medication to postoperative atrial fibrillation (POAF) in patients undergoing cardiac surgery. Methods. We searched PubMed, Embase, and Cochrane Library (from inception to March 2016) for eligible studies. The outcomes were the effects of preoperative hypertension, preoperative calcium antagonists regimen, preoperative ACE inhibitors regimen, and preoperative beta blocking agents regimen with POAF. We calculated pooled risk ratios (OR) and 95% CIs using random- or fixed-effects models. Results. Twenty-five trials involving 130087 patients were listed. Meta-analysis showed that the number of preoperative hypertension patients in POAF group was significantly higher (P < 0.05), while we found that there are no significant differences between two groups in Asia patients by subgroup analysis, which is in contrast to other outcomes. Compared with the Non-POAF group, the number of patients who used calcium antagonists and ACE inhibitors preoperatively in POAF group was significantly higher (P < 0.05). And we found that there were no significant differences between two groups of preoperative beta blocking agents used (P = 0.08). Conclusions. Preoperative hypertension and preoperative antihypertensive medication in patients undergoing cardiac operations seem to be associated with higher risk of POAF.

Investigation of selection bias in the association of race with prevalent atrial fibrillation in a national cohort study: REasons for Geographic And Racial Differences in Stroke (REGARDS)

PURPOSE

Atrial fibrillation (AF) is diagnosed more commonly in whites than blacks in the United States. In epidemiologic studies, selection bias could induce a noncausal positive association of white race with prevalent AF if voluntary enrollment was influenced by both race and AF status. We investigated whether nonrandom enrollment biased the association of race with prevalent self-reported AF in the US-based REasons for Geographic And Racial Differences in Stroke Study (REGARDS).

METHODS

REGARDS had a two-stage enrollment process, allowing us to compare 30,183 fully enrolled REGARDS participants with 12,828 people who completed the first-stage telephone survey but did not complete the second-stage in-home visit to finalize their REGARDS enrollment (telephone-only participants).

RESULTS

REGARDS enrollment was higher among whites (77.1%) than among blacks (62.3%) but did not differ by self-reported AF status. The prevalence of AF was 8.45% in whites and 5.86% in blacks adjusted for age, sex, income, education, and perceived general health. The adjusted white/black prevalence ratio of self-reported AF was 1.43 (95% CI, 1.32-1.56) among REGARDS participants and 1.38 (1.22-1.55) among telephone-only participants.

CONCLUSIONS

These findings suggest that selection bias is not a viable explanation for the higher prevalence of self-reported AF among whites in population studies such as REGARDS.

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.

Comparative effectiveness of pharmacotherapies for prevention of atrial fibrillation following coronary artery bypass surgery

Risk of atrial fibrillation (AF) after coronary artery bypass grafting (CABG) is high, yet the effectiveness of guideline-recommended preoperative prophylaxis in clinical practice remains uncertain. We determined the utilization and variation of preoperative AF prevention and assessed the comparative effectiveness of alternative drugs using the Society of Thoracic Surgeons multicenter Contemporary Analysis of Perioperative Cardiovascular Surgical Care (CAPS-Care) registry. Among 2,177 patients who underwent high-risk CABG and/or valve surgery, the mean age was 71 ± 9, 66% were men, 26% had chronic lung disease, and 21% had cerebrovascular disease. Overall use of AF prophylaxis was 84% and varied across sites (range 52% to 100%). The most common preventive agents were beta blockers (72%), followed by calcium antagonists (17%). Postoperatively, 30% (n = 646) developed AF at a median of 2 (25th to 75th percentiles: 1 to 3) days after surgery. Increasing age, height, white race, body mass index >35, New York Heart Association class IV heart failure, preoperative dialysis, and concomitant aortic valve replacement were associated with greater odds of postoperative AF (p <0.05 for all). Preoperative amiodarone use was associated with a trend to reduction of postoperative AF (26%, adjusted odds ratio 0.72 [95% confidence interval 0.51 to 1.00], p = 0.052). After adjustment, the odds of postoperative AF were not statistically different across agents. In conclusion, use of AF prophylaxis before surgery varied significantly. In this high-risk population, we were unable to demonstrate that any of the commonly used preventive agents were associated with lower rates of AF compared with alternatives or no treatment.

Impact of race and postoperative atrial fibrillation on long-term survival after coronary artery bypass grafting

BACKGROUND AND AIM

Postoperative atrial fibrillation (POAF) is a known predictor of in-hospital morbidity and short-term survival after coronary artery bypass grafting (CABG). The impact of race and long-term survival has not been examined in this population. We aimed to examine the influence of these factors on long-term survival in patients undergoing CABG.

METHODS

Patients undergoing first-time, isolated CABG between 1992 and 2011 were included in this study. Long-term survival was compared in patients with and without POAF and stratified by race. Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model.

RESULTS

A total of 2,907 (22%) patients developed POAF (black n=370; white n=2,537) following CABG (N=13,165). Median follow-up for study participants was 8.2 years. Long-term survival after CABG differed by POAF status and race (no POAF: HR=1.0; white POAF: adjusted HR=1.1, 95% CI=1.06-1.2; black POAF: adjusted HR=1.4, 95% CI=1.2-1.6; pTrend=0.0002). lack POAF patients also died sooner after surgery than their white counterparts (adjusted HR=1.2, 95% CI=1.02-1.4).

CONCLUSION

Black race was a statistically significant predictor of decreased survival among POAF patients after CABG. This finding provides useful outcome information for surgeons and their patients.

Prediction of Atrial Fibrillation by B-type Natriuretic Peptide

Background: Although several conditions have been proposed as risk factors contributing to the incidence of atrial fibrillation, many individuals without such 'risk factors' also suffer from atrial fibrillation. The present study tested the hypothesis that the risk of new-onset atrial fibrillation increases with increasing circulating levels of B-type natriuretic peptide in the general population. Methods: Participants in our health checkup program without atrial fibrillation or a history of atrial fibrillation were enrolled (n=10,058, 54.3±11.3 years old). After baseline evaluation, subjects were followed up for the median of 1,791 days with the endpoint being the new onset of atrial fibrillation. Results: Atrial fibrillation occurred in 53 subjects during the follow-up period (1.16 per 1,000 person-year). The risk of new-onset atrial fibrillation increased across the gender-specific quartiles of B-type natriuretic peptide levels at baseline. In multivariate Cox proportional hazard regression analysis where B-type natriuretic peptide concentrations were taken as a continuous variable, B-type natriuretic peptide was a significant predictor of new onset of atrial fibrillation after adjustment for possible factors (hazard ratio 5.65 [95% CI 2.63-12.41]). Conclusions: The risk of new onset of atrial fibrillation increases with increasing B-type natriuretic peptide levels in the general population. Measurement of B-type natriuretic peptide may improve the prediction of incident atrial fibrillation.

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.

African american race and prevalence of atrial fibrillation:a meta-analysis

Background. It has been observed that African American race is associated with a lower prevalence of atrial fibrillation (AF) compared to Caucasian race. To better quantify the association between African American race and AF, we performed a meta-analysis of published studies among different patient populations which reported the presence of AF by race. Methods. A literature search was conducted using electronic databases between January 1999 and January 2011. The search was limited to published studies in English conducted in the United States, which clearly defined the presence of AF in African American and Caucasian subjects. A meta-analysis was performed with prevalence of AF as the primary endpoint. Results. In total, 10 studies involving 1,031,351 subjects were included. According to a random effects analysis, African American race was associated with a protective effect with regard to AF as compared to Caucasian race (odds ratio 0.51, 95% CI 0.44 to 0.59, P < 0.001). In subgroup analyses, African American race was significantly associated with a lower prevalence of AF in the general population, those hospitalized or greater than 60 years old, postcoronary artery bypass surgery patients, and subjects with heart failure. Conclusions. In a broad sweep of subjects in the general population and hospitalized patients, the prevalence of AF in African Americans is consistently lower than in Caucasians.

Comparison of frequency of atrial fibrillation after coronary artery bypass grafting in African Americans versus European Americans

In the general population, African Americans experience atrial fibrillation (AF) less frequently than European Americans. This difference could also exist in the incidence of this arrhythmia after cardiac surgery, but this possibility has been insufficiently examined. To test the association of such an ethnic difference, we compared the incidence of postoperative AF in a consecutive series of 2,312 African Americans and 6,054 European Americans who underwent isolated coronary artery bypass grafting from July 2000 to June 2007. Raw differences between the cohorts in the incidence of new AF were adjusted to take into account the baseline differences. Postoperatively, new-onset AF developed in 504 (22%) of 2,312 African-American patients and in 1,838 (30%) of 6,054 European-American patients (p <0.01). After adjustment with logistic regression analysis for numerous baseline differences, African Americans remained less likely to develop AF (odds ratio 0.63, 95% confidence interval 0.55 to 0.72; p <0.001). Risk was also adjusted using propensity matching. In that analysis, 457 (22%) of 2,059 African-American patients had postoperative AF, as did 597 (29%) of 2,059 matched European-American patients (p <0.01). In conclusion, AF was significantly less common among African-American patients than among European-American patients after coronary artery bypass grafting.

Differential impact of race and risk factors on incidence of atrial fibrillation

Despite some common risk factors for atrial fibrillation (AF) being more prevalent among blacks, African Americans are increasingly being reported with lower prevalence and incidence of AF compared with whites. Contemporary studies have not provided a complete explanation for this apparent AF paradox in African Americans. Although many traditional and novel risk factors for AF have been identified, the role of ethnic-specific risk factors has not been examined. Whereas hypertension has been the most common risk factor associated with AF, coronary artery disease also plays an important role in AF pathophysiology in whites. Thereby, elucidating the role of ethnic-specific risk factors for AF may provide important insight into why African Americans are protected from AF or why whites are more prone to develop the arrhythmia. The link between AF susceptibility and genetic processes has only been recently uncovered. Polymorphisms in renin-angiotensin system genes have been characterized as predisposing to AF under certain environmental conditions. Several ion channel genes, signaling molecules, and several genetic loci have been linked with AF. Thereby, studies investigating genetic variants contributing to the differential AF risk in individuals of African American versus European ancestry may also provide important insight into the etiology of the AF paradox in blacks.