Ethnic differences in atrial fibrillation identified using implanted cardiac devices

Atrial fibrillation in Black American patients: A review of genetics, risk factors, and outcomes

Atrial fibrillation (AF), the most common arrhythmia in the United States, affects 6 million Americans, with numbers projected to increase to 12 million by 2030. A racial paradox difference in the incidence and prevalence of AF exists between Black and White Americans. Black Americans are less prone than White Americans to development of AF, but they display a higher burden of modifiable risk factors for cardiovascular disease and higher rates of ischemic stroke. Data pertaining to the American Heart Association Life's Simple 7 (LS7) health metrics show that Black Americans have suboptimal LS7 scores compared with White Americans on average despite lower genetic predisposition to AF. This trend suggests the impact of cardiovascular health on the development and progression of AF. Social, genetic, and lifestyle risk factors have been shown to play a role in the racial paradox and AF outcomes in Black Americans. This review summarizes factors contributing to the racial paradox and discusses suggestions for improved health outcomes in Black Americans with AF.

Racial Differences in Device-Detected Incident Atrial Fibrillation

BACKGROUND

Prior research suggests Black individuals have a lower risk of atrial fibrillation (AF) than White individuals, but this may be related to the underdetection of AF. Whether this trend persists using highly sensitive methods of AF diagnosis has not been well-studied.

OBJECTIVES

The objective of this study was to use cardiac implantable electronic devices (CIEDs) capable of AF diagnosis to compare AF incidence between Black and White individuals.

METHODS

This was a retrospective observational study involving Black and White patients who had a CIED implanted between January 1, 2007, and June 1, 2019. Patients with insertable cardiac monitors, insufficient monitoring, or prior AF were excluded. The primary endpoint was the overall adjusted incidence of device-detected AF between Black and White individuals.

RESULTS

Of 441,047 patients with a CIED implanted during the study period, 88,427 patients (mean age, 69 ± 13 years; 80,382 White [91%]; 55,840 male [63%]) were included in analysis. The mean follow-up duration was 2.2 ± 1.7 years, and 35,143 patients (40%) had device-detected AF. The crude incidence of AF was greater among White, compared with Black, individuals (27.95 vs 24.86 cases per 100 person-years, P < 0.001). After adjusting for age, sex, and medical comorbidities, the hazard of AF was similar between Black and White individuals (HR, 1.02; 95% CI: 0.98-1.06). In subgroup analysis by type of CIED, White individuals had a greater hazard of AF in the pacemaker cohort, whereas Black individuals had a greater hazard of AF in the implantable cardioverter defibrillator cohort.

CONCLUSIONS

The adjusted hazard of AF was similar between Black and White individuals with CIEDs.

Global Results of Implantable Loop Recorder for Detection of Atrial Fibrillation After Stroke: Reveal LINQ Registry

BACKGROUND

We aimed to quantify the incidence of atrial fibrillation (AF) in patients with cryptogenic stroke globally, as well as separately in patients in and outside of Japan, using an implantable loop recorder from a prospective, observational, Reveal LINQ Registry.

METHODS AND RESULTS

Patients developing cryptogenic stroke and monitored by implantable loop recorder for searching AF were studied. The primary end point was incidence of AF within 36 months after insertion. Secondary end points were recurrent ischemic stroke/transient ischemic attack and AF-related treatment strategies. A total of 271 patients (61.6±14.3 years, 170 men, 60 from Japan) were enrolled from 12 countries. AF was detected in 28.2% at 36 months. The median time from enrollment to AF detection was 7.9 months. During the first 12 months, the AF detection rate slope was relatively steeper in the Japanese subgroup versus non-Japanese patients. However, by 3 years, the cumulative incidence of AF detection did not differ between groups. Age was the only variable associated with AF detection (hazard ratio, 1.05 [95% CI, 1.02-1.07] per year), trending higher in older age groups. Of the 271 patients, 11 (4.1%) developed recurrent ischemic stroke/transient ischemic attack; AF was detected by implantable loop recorder in only 1 of these patients. Patients with detected AF were more commonly taking oral anticoagulation than those without AF at the last follow-up (64.7% versus 25.3%, P<0.001).

CONCLUSIONS

The rate of AF detection was similar to other studies in stroke populations monitored by implantable loop recorders, including CRYSTAL-AF (Cryptogenic Stroke and Underlying Atrial Fibrillation), STROKE-AF (Stroke of Unknown Cause and Underlying Atrial Fibrillation) and PER-DIEM (Post-Embolic Rhythm Detection With Implantable Versus External Monitoring). Patients with detected AF more commonly initiated anticoagulation than those without AF.

Burden of cardiovascular disease among elderly: based on the Global Burden of Disease Study 2019

BACKGROUND

The burden of elderly cardiovascular disease (CVD) has received increasing attention with population ageing worldwide.

AIMS

We reported on the global CVD burden in elderly individuals over 70, 1990-2019.

METHODS AND RESULTS

Based on the Global Burden of Disease Study 2019, elderly CVD burden data were analysed. Temporal burden trends were analysed with the joinpoint model. The slope index and concentration index were used to evaluate health inequality. From 1990 to 2019, the global elderly CVD incidence, prevalence, death, and disability-adjusted life year rates generally decreased. However, the current burden remains high. The rapid growth in burden in parts of sub-Saharan Africa and Asia is a cause for concern. Countries with a higher socio-demographic index (SDI) have generally seen a greater decrease in burden, while countries with a lower SDI have generally experienced increases or smaller declines in burden. Health inequality analysis confirmed that the burden was gradually concentrating towards countries with a low SDI. Among the different CVDs, ischaemic heart disease causes the greatest burden in elderly individuals. Most CVD burdens increase with age, but stroke and peripheral vascular disease show markedly different distributional characteristics. In addition, the burden of hypertensive heart disease shows an unusual shift towards high-SDI countries. High systolic blood pressure was consistently the leading risk factor for CVD among elderly individuals.

CONCLUSION

The burden of CVD in older people remains severe and generally tends to shift to lower-SDI countries. Policymakers need to take targeted measures to reduce its harm.

Global Burden of Atrial Fibrillation and Flutter by National Income: Results From the Global Burden of Disease 2019 Database

Background Atrial fibrillation (AF) and atrial flutter (AFL) are common conditions that can lead to significant morbidity and death. We aimed to understand the distribution and disparities of the global burden of AF/AFL as well as the underlying risk factors. Methods and Results Data on the AF/AFL burden from the Global Burden of Disease data set were analyzed for the years 1990 to 2019, with countries grouped into low, lower-middle, upper-middle, and high national income classes according to World Bank categories. Data were supplemented with World Health Organization and World Bank information. The prevalence of AF/AFL has more than doubled (+120.7%) since 1990 in all income groups, though with a larger increment in middle-income countries (+146.6% in lower-middle- and +145.2% in upper-middle-income countries). In absolute numbers, 63.4% of AF/AFL cases originate from upper-middle-income countries, although the relative prevalence is highest in high-income countries. Prevalence of AF/AFL appears to be correlated with medical doctor rate and life expectancy. The most relevant AF/AFL risk factors are unevenly distributed among income classes, with elevated blood pressure as the only risk factor that becomes less common with increasing income. The development of these risk factors differed over time. Conclusions The global burden of AF/AFL is increasing in all income groups and is more pronounced in middle-income countries, with further growth to be expected. Underdiagnosis of AF/AFL in low- and middle-income countries may contribute to lower reported prevalence. The risk factor distribution varies between income groups.

Atrial Fibrillation and Reperfusion Therapy in Acute Ischaemic Stroke Patients: Prevalence and Outcomes-A Comprehensive Systematic Review and Meta-Analysis

Atrial fibrillation (AF) significantly contributes to acute ischaemic stroke (AIS), yet its precise influence on clinical outcomes post-intravenous thrombolysis (IVT) and post-endovascular thrombectomy (EVT) has remained elusive. Furthermore, the overall prevalence of AF in AIS patients undergoing reperfusion therapy has not been clearly determined. Employing random-effects meta-analyses, this research aimed to estimate the pooled prevalence of AF among AIS patients undergoing reperfusion therapy, while also examining the association between AF and clinical outcomes such as functional outcomes, symptomatic intracerebral haemorrhage (sICH) and mortality. Studies comparing AF and non-AF patient groups undergoing reperfusion therapy were identified and included following an extensive database search. Forty-nine studies (n = 66,887) were included. Among IVT patients, the prevalence of AF was 31% (Effect Size [ES] 0.31 [95%CI 0.28-0.35], p < 0.01), while in EVT patients, it reached 42% (ES 0.42 [95%CI 0.38-0.46], p < 0.01), and in bridging therapy (BT) patients, it stood at 36% (ES 0.36 [95%CI 0.28-0.43], p < 0.01). AF was associated with significantly lower odds of favourable 90-day functional outcomes post IVT (Odds Ratio [OR] 0.512 [95%CI 0.376-0.696], p < 0.001), but not post EVT (OR 0.826 [95%CI 0.651-1.049], p = 0.117). Our comprehensive meta-analysis highlights the varying prevalence of AF among different reperfusion therapies and its differential impact on patient outcomes. The highest pooled prevalence of AF was observed in EVT patients, followed by BT and IVT patients. Interestingly, our analysis revealed that AF was significantly associated with poorer clinical outcomes following IVT. Such an association was not observed following EVT.

A nationwide analysis of the outcomes in hospitalized patients with atrial fibrillation and temperature-related illnesses

OBJECTIVES

The authors evaluated mortality and indices of cost of care among inpatients with Atrial Fibrillation (AF) and a diagnosis of a Temperature-Related Illness (TRI). The authors also assessed trends in the prevalence of TRIs among AF hospitalizations.

METHODS

In this cross-sectional study, the authors used discharge data from the Nationwide Inpatient Sample (NIS) collected between January 2005 and September 2015 to identify patients with a diagnosis of AF and TRI. Outcomes of interest included in-hospital mortality, invasive mechanical ventilation, hospital length of stay, and cost of hospitalization.

RESULTS

A total of 37,933 encounters were included. The median age was 79 years. Males were slightly overrepresented relative to females (54.2% vs. 45.8%, respectively). Although Blacks were only 6.6% of the cohort, they represented 12.2% of the TRI cases. Compared to non-TRI-related hospitalizations, a diagnosis of a TRI was associated with an increased likelihood of invasive mechanical ventilation (16.5% vs. 4.1%, p < 0.001), longer length-of-stay (5 vs. 4 days, p < 0.001), higher cost of care (10,082 vs. 8,607, in US dollars p < 0.001), and increased mortality (18.6% vs. 5.1%, p < 0.001). Compared to non-TRI, cold-related illness portends higher odds of mortality 4.68, 95% Confidence Interval (4.35-5.04), p < 0.001, and heat-related illness was associated with less odds of mortality, but this was not statistically significant 0.77 (0.57-1.03), p = 0.88.

CONCLUSION

The occurrence of TRI among hospitalized AF patients is small but there is an increasing trend in the prevalence, which more than doubled over the decade in this study. Individuals with AF who are admitted with a TRI face significantly poorer outcomes than those admitted without a TRI including higher mortality. Cold-related illness is associated with higher odds of mortality. Further research is required to elucidate the pathogenic mechanisms underlying these findings and identify strategies to prevent TRIs in AF patients.

Effect of atrial fibrillation on mortality in SARS-CoV-2 patients: A propensity score-matched analysis of nationwide hospitalizations in the United States

Background

Atrial fibrillation (AF) is one of the most common arrhythmias encountered in patients with SARS-CoV-2 infection. There are racial disparities in the incidence of AF and COVID-19. Several studies have reported an association between AF and mortality. However, it remains to be determined if AF represents an independent risk factor for COVID-19-related mortality.

Methods

A propensity score-matched (PSM) analysis was performed using data from the National Inpatient Sample to assess the risk of mortality among patients hospitalized with SARS-CoV-2 infection and incident AF from March 2020 through December 2020.

Results

AF was less common among patients who tested positive for SARS-CoV-2 as compared to those who tested negative (6.8% vs 7.4%, p < 0.001). White individuals with the virus had an increased incidence of AF but had lower mortality rates relative to Black and Hispanic patients. After PSM analysis, AF retained a significantly increased odds of mortality among patients with SARS-CoV-2 (OR: 1.35, CI: 1.29-1.41, p < 0.001).

Conclusion

This PSM analysis shows that AF is an independent risk factor for inpatient mortality in those with SARS-CoV-2 infection and that White patients, while having a higher burden of SARS-CoV-2 and AF, demonstrate a significantly lower mortality rate as compared to their Black and Hispanic counterparts.

COVID-19 pandemic and trends in new diagnosis of atrial fibrillation: A nationwide analysis of claims data

BACKGROUND

Atrial fibrillation (AF) is associated with a five-fold increased risk of stroke and a two-fold increased risk of death. We aimed to quantify changes in new diagnoses of AF following the onset of the COVID-19 pandemic. Investigating changes in new diagnoses of AF is of relevance because delayed diagnosis interferes with timely treatment to prevent stroke, heart failure, and death.

METHODS

Using De-identified Optum's Clinformatics® Data Mart, we identified 19,500,401 beneficiaries continuously enrolled for 12 months in 2016-Q3 2020 with no history of AF. The primary outcome was new AF diagnoses per 30-day interval. Secondary outcomes included AF diagnosis in the inpatient setting, AF diagnosis in the outpatient setting, and ischemic stroke as initial manifestation of AF. We constructed seasonal autoregressive integrated moving average models to quantify changes in new AF diagnoses after the onset of the COVID-19 pandemic (3/11/2020, date of pandemic declaration). We tested whether changes in the new AF diagnoses differed by race and ethnicity.

RESULTS

The average age of study participants was 51.0±18.5 years, and 52% of the sample was female. During the study period, 2.7% of the study sample had newly-diagnosed AF. New AF diagnoses decreased by 35% (95% CI, 21%-48%) after the onset of the COVID-19 pandemic, from 1.14 per 1000 individuals (95% CI, 1.05-1.24) to 0.74 per 1000 (95% CI, 0.64 to 0.83, p-value<0.001). New AF diagnoses decreased by 37% (95% CI, 13%- 55%) in the outpatient setting and by 29% (95% CI, 14%-43%) in the inpatient setting. The decrease in new AF diagnoses was similar across racial and ethnic subgroups.

CONCLUSION

In a nationwide cohort of 19.5 million individuals, new diagnoses of AF decreased substantially following the onset of the COVID-19 pandemic. Our findings evidence pandemic disruptions in access to care for AF, which are concerning because delayed diagnosis interferes with timely treatment to prevent complications.

Racial Disparity in Referral for Catheter Ablation for Atrial Fibrillation at a Single Integrated Health System

Background Guidelines recommend catheter ablation of atrial fibrillation (AFCA) as an option for rhythm control. Studies have shown that Black patients are less likely to undergo AFCA compared with White patients. We investigated whether differences in referral patterns play a role in this observed disparity. Methods and Results Using an integrated repository from the electronic medical record at Northwestern Medicine, we conducted a retrospective cohort study of outpatients with newly diagnosed atrial fibrillation. Baseline characteristics by race and ethnicity were compared. Logistic regression models adjusted for socioeconomic and health factors were constructed to determine the association between race and ethnicity and binary dependent variables including referrals and visits to general cardiology and cardiac electrophysiology (EP) and AFCA. Of 5445 patients analyzed, 4652 were non-Hispanic White (NHW) and 793 were non-Hispanic Black (NHB). In adjusted models, NHB patients initially diagnosed with atrial fibrillation in internal medicine and primary care had a significantly greater odds of referral to general cardiology; among all patients in the cohort, there was no significant difference in the odds of referral to EP between NHB and NHW patients; and there were no differences in the odds of completing a visit in general cardiology or EP. Among patients completing an EP visit, NHB patients were less likely to undergo AFCA (odds ratio, 0.63 [95% CI, 0.40-0.98], P=0.040). Conclusions Similar referral rates to general cardiology and EP were observed between NHB and NHW patients. Despite this, NHB patients were less likely to undergo AFCA.

Epicardial adipose tissue, obesity and the occurrence of atrial fibrillation: an overview of pathophysiology and treatment methods

INTRODUCTION

Obesity is a chronic disease, which has significant health consequences and is a staggering burden to health care systems. Obesity can have harmful effects on the cardiovascular system, including heart failure, hypertension, coronary heart disease, and atrial fibrillation (AF). One of the possible substrates might be epicardial adipose tissue (EAT), which can be the link between AF and obesity. EAT is a fat deposit located between the myocardium and the visceral pericardium. Numerous studies have demonstrated that EAT plays a pivotal role in this relationship regarding atrial fibrillation.

AREAS COVERED

This review will focus on the role of obesity and the occurrence of atrial fibrillation (AF) and examine the connection between these and epicardial adipose tissue (EAT). The first part of this review will explain the pathophysiology of EAT and its association with the occurrence of AF. Secondly, we will review bariatric and metabolic surgery and its effects on EAT and AF.

EXPERT COMMENTARY

In this review, the epidemiology, pathophysiology, and treatments methods of AF are explained. Secondly the effects on EAT were elucidated. Due to the complex pathophysiological link between EAT, AF, and obesity, it is still uncertain which treatment strategy is superior.

Epidemiology of atrial fibrillation in the All of Us Research Program

BACKGROUND

The prevalence, incidence and risk factors of atrial fibrillation (AF) in a large, geographically and ethnically diverse cohort in the United States have not been fully described.

METHODS

We analyzed data from 173,099 participants of the All of Us Research Program recruited in the period 2017-2019, with 92,318 of them having electronic health records (EHR) data available, and 35,483 having completed a medical history survey. Presence of AF at baseline was identified from self-report and EHR records. Incident AF was obtained from EHR. Demographic, anthropometric and clinical risk factors were obtained from questionnaires, baseline physical measurements and EHR.

RESULTS

At enrollment, mean age was 52 years old (range 18-89). Females and males accounted for 61% and 39% respectively. Non-Hispanic Whites accounted for 67% of participants, with non-Hispanic Blacks, non-Hispanic Asians and Hispanics accounting for 26%, 4% and 3% of participants, respectively. Among 92,318 participants with available EHR data, 3,885 (4.2%) had AF at the time of study enrollment, while the corresponding figure among 35,483 with medical history data was 2,084 (5.9%). During a median follow-up of 16 months, 354 new cases of AF were identified among 88,433 eligible participants. Individuals who were older, male, non-Hispanic white, had higher body mass index, or a prior history of heart failure or coronary heart disease had higher prevalence and incidence of AF.

CONCLUSION

The epidemiology of AF in the All of Us Research Program is similar to that reported in smaller studies with careful phenotyping, highlighting the value of this new resource for the study of AF and, potentially, other cardiovascular diseases.

Racial and Ethnic Considerations in Patients With Atrial Fibrillation: JACC Focus Seminar 5/9

Atrial fibrillation (AF) affects at least 60 million individuals globally and is associated with substantial impacts on morbidity, mortality, and health care expenditures. This review focuses on how race and ethnicity influence AF epidemiology, risk prediction, treatment, and outcomes; knowledge gaps in these areas are identified. Most AF studies have predominantly included White populations, with an underrepresentation of racial and ethnic groups, including but not limited to Black, Hispanic, and Indigenous individuals. Enhancement and implementation of AF risk prediction, prevention, and management call for studies that will gather accurate race-based epidemiologic data and evaluate social determinants and genetic factors in the context of multiple races and ethnicities. Available studies highlight inequities in access to treatment as well as outcomes between White individuals and persons of other races/ethnicities. These inequities will need to be addressed by a renewed emphasis on structural and social determinants of health that contribute to AF.

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.

Risk of incident atrial fibrillation with low-to-moderate alcohol consumption is associated with gender, region, alcohol category: a systematic review and meta-analysis

AIMS 

The association between low-to-moderate alcohol consumption and atrial fibrillation (AF) has yet to be fully elucidated. The main purpose of this meta-analysis was to estimate the risk of incident AF related to low-to-moderate alcohol consumption.

METHODS AND RESULTS 

A meta-analysis was performed on 13 publications discussing the estimated risk for AF with habitual low-to-moderate alcohol intake in 10 266 315 participants. Graphical augmentations to the funnel plots were used to illustrate the potential impact of additional evidence on the current meta-analysis. Thirteen eligible studies were included in this meta-analysis. We found that moderate alcohol consumption was associated with an increased risk of incident AF in males [hazard ratio (HR) 1.09, 95% confidence interval (CI): 1.07-1.11, P < 0.00001], Europeans (HR 1.32, 95% CI: 1.23-1.42, P < 0.00001), and Asians (HR 1.09, 95% CI: 1.07-1.11, P < 0.00001). Moderate beer consumption was associated with an increased risk of developing AF (HR 1.11, 95% CI: 1.02-1.21, P = 0.01). Low alcohol consumption conferred an increased risk of AF in males (HR 1.14, 95% CI: 1.01-1.28, P = 0.04) and Europeans (HR 1.12, 95% CI: 1.07-1.17, P < 0.00001).

CONCLUSIONS 

This analysis represents the increased risk of incident AF in males, Europeans, and Asians at moderate alcohol consumption levels and in males and Europeans at low alcohol consumption levels. Those who drink any preferred alcohol beverage at moderate levels should be cautious for incident AF. More studies are warranted to find those factors that influence alcohol's effect on predisposing AF.

Identifying Atrial Fibrillation Mechanisms for Personalized Medicine

Atrial fibrillation (AF) is a major cause of heart failure and stroke. The early maintenance of sinus rhythm has been shown to reduce major cardiovascular endpoints, yet is difficult to achieve. For instance, it is unclear how discoveries at the genetic and cellular level can be used to tailor pharmacotherapy. For non-pharmacologic therapy, pulmonary vein isolation (PVI) remains the cornerstone of rhythm control, yet has suboptimal success. Improving these therapies will likely require a multifaceted approach that personalizes therapy based on mechanisms measured in individuals across biological scales. We review AF mechanisms from cell-to-organ-to-patient from this perspective of personalized medicine, linking them to potential clinical indices and biomarkers, and discuss how these data could influence therapy. We conclude by describing approaches to improve ablation, including the emergence of several mapping systems that are in use today.

Racial and Ethnic Differences in the Management of Atrial Fibrillation

Atrial fibrillation (AF) is the most common clinical arrhythmia, and it results in adverse outcomes and increased healthcare costs. Racial and ethnic differences in AF management, although recognized, are poorly understood. This review summarizes racial differences in AF epidemiology, genetics, clinical presentation, and management. In addition, it highlights the underrepresentation of racial and ethnic populations in AF clinical trials, especially trials focused on stroke prevention. Specific strategies are proposed for future research and initiatives that have potential to eliminate racial and ethnic differences in the care of patients with AF. Addressing racial and ethnic disparities in healthcare access, enrollment in clinical trials, resource allocation, prevention, and management will likely narrow the gaps in the care and outcomes of racial and ethnic minorities suffering from AF.

New-onset atrial fibrillation in patients with worsening heart failure and coronary artery disease: an analysis from the COMMANDER-HF trial

BACKGROUND

Atrial fibrillation (AF) in the presence of heart failure (HF) is associated with poor outcomes including a high-risk of stroke and other thromboembolic events. Identifying patients without AF who are at high-risk of developing this arrhythmia has important clinical implications.

AIMS

To develop a risk score to identify HF patients at high risk of developing AF.

METHODS

The COMMANDER-HF trial enrolled 5022 patients with HF and a LVEF ≤ 40%, history of coronary artery disease, and absence of AF at baseline (confirmed with an electrocardiogram). Patients were randomized to either rivaroxaban (2.5 mg bid) or placebo. New-onset AF was confirmed by the investigator at study visits.

RESULTS

241 (4.8%) patients developed AF during the follow-up (median 21 months). Older age (≥ 65 years), LVEF < 35%, history of PCI or CABG, White race, SBP < 110 mmHg, and higher BMI (≥ 25 kg/m²) were independently associated with risk of new-onset AF, whereas the use of DAPT was associated with a lower risk of new-onset AF. We then built a risk score from these variables (with good accuracy C-index = 0.71) and calibration across observed and predicted tertiles of risk. New-onset AF events rates increased steeply by increasing tertiles of the risk-score. Compared to tertile 1, the risk of new-onset AF was 2.5-fold higher in tertile 2, and 6.3-fold higher in tertile 3. Rivaroxaban had no effect in reducing new-onset AF. In time-updated models, new-onset AF was associated with a higher risk of subsequent all-cause death: HR (95%CI) 1.38 (1.11-1.73).

CONCLUSIONS

A well-calibrated risk-score identified patients at risk of new-onset AF in the COMMANDER-HF trial. Patients who developed AF had a higher risk of subsequent death. Risk of new-onset atrial fibrillation in patients with HFrEF and coronary artery disease.

World Heart Federation Roadmap on Atrial Fibrillation - A 2020 Update

The World Heart Federation (WHF) commenced a Roadmap initiative in 2015 to reduce the global burden of cardiovascular disease and resultant burgeoning of healthcare costs. Roadmaps provide a blueprint for implementation of priority solutions for the principal cardiovascular diseases leading to death and disability. Atrial fibrillation (AF) is one of these conditions and is an increasing problem due to ageing of the world's population and an increase in cardiovascular risk factors that predispose to AF. The goal of the AF roadmap was to provide guidance on priority interventions that are feasible in multiple countries, and to identify roadblocks and potential strategies to overcome them. Since publication of the AF Roadmap in 2017, there have been many technological advances including devices and artificial intelligence for identification and prediction of unknown AF, better methods to achieve rhythm control, and widespread uptake of smartphones and apps that could facilitate new approaches to healthcare delivery and increasing community AF awareness. In addition, the World Health Organisation added the non-vitamin K antagonist oral anticoagulants (NOACs) to the Essential Medicines List, making it possible to increase advocacy for their widespread adoption as therapy to prevent stroke. These advances motivated the WHF to commission a 2020 AF Roadmap update. Three years after the original Roadmap publication, the identified barriers and solutions were judged still relevant, and progress has been slow. This 2020 Roadmap update reviews the significant changes since 2017 and identifies priority areas for achieving the goals of reducing death and disability related to AF, particularly targeted at low-middle income countries. These include advocacy to increase appreciation of the scope of the problem; plugging gaps in guideline management and prevention through physician education, increasing patient health literacy, and novel ways to increase access to integrated healthcare including mHealth and digital transformations; and greater emphasis on achieving practical solutions to national and regional entrenched barriers. Despite the advances reviewed in this update, the task will not be easy, but the health rewards of implementing solutions that are both innovative and practical will be great.

Left atrial, pulmonary vein, and left atrial appendage anatomy in Indigenous individuals: Implications for atrial fibrillation

Background

Indigenous Australians experience a greater burden of AF. Whether this is in-part due to differences in arrhythmogenic structures that appear to contribute to AF differences amongst other ethnicities is not known.

Methods

We studied forty individuals matched for ethnicity and other AF risk factors. Computed tomography imaging was used to characterise left atrial (LA), pulmonary vein (PV), and left atrial appendage (LAA) anatomy.

Results

There were no significant differences in LA diameters or volumes between Indigenous and non-Indigenous Australians. Similarly, we could not detect any consistent differences in PV number, morphology, diameters, or ostial characteristics according to ethnicity. LAA analyses suggested that Indigenous Australians may have a greater proportion of non chickenwing LAA type, and a tendency for eccentric, oval-shaped LAA ostia; however, there were no other differences seen with regards to LAA volume or depth. Indexed values for LA, PV and LAA anatomy corrected for body size were broadly similar.

Conclusions

In a cohort of individuals matched for AF risk factors, we could find no strong evidence of ethnic differences in LA, PV, and LAA characteristics that may explain a predisposition of Indigenous Australians for atrial arrhythmogenesis. These findings, in conjunction with our previous data showing highly prevalent cardiometabolic risk factors in Indigenous Australians with AF, suggest that it is these conditions that are more likely responsible for the AF substrate in these individuals. Continued efforts should therefore be directed towards risk factor management in an attempt to prevent and minimise the effects of AF in Indigenous Australians.

Racial Differences in Atrial Cardiopathy Phenotypes in Patients With Ischemic Stroke

OBJECTIVE

To test the hypothesis that thrombogenic atrial cardiopathy may be relevant to stroke-related racial disparities, we compared atrial cardiopathy phenotypes between Black vs White patients with ischemic stroke.

METHODS

We assessed markers of atrial cardiopathy in the Greater Cincinnati/Northern Kentucky Stroke Study, a study of stroke incidence in a population of 1.3 million. We obtained ECGs and reports of echocardiograms performed during evaluation of stroke during the 2010/2015 study periods. Patients with atrial fibrillation (AF) or flutter (AFL) were excluded. Investigators blinded to patients' characteristics measured P-wave terminal force in ECG lead V1 (PTFV1), a marker of left atrial fibrosis and impaired interatrial conduction, and abstracted left atrial diameter from echocardiogram reports. Linear regression was used to examine the association between race and atrial cardiopathy markers after adjustment for demographics, body mass index, and vascular comorbidities.

RESULTS

Among 3,426 ischemic stroke cases in Black or White patients without AF/AFL, 2,391 had a left atrial diameter measurement (mean, 3.65 ± 0.70 cm). Black race was associated with smaller left atrial diameter in unadjusted (β coefficient, -0.11; 95% confidence interval [CI], -0.17 to -0.05) and adjusted (β, -0.15; 95% CI, -0.21 to -0.09) models. PTFV1 measurements were available in 3,209 patients (mean, 3,434 ± 2,525 μV*ms). Black race was associated with greater PTFV1 in unadjusted (β, 1.59; 95% CI, 1.21-1.97) and adjusted (β, 1.45; 95% CI, 1.00-1.80) models.

CONCLUSIONS

We found systematic Black-White racial differences in left atrial structure and pathophysiology in a population-based sample of patients with ischemic stroke.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that atrial cardiopathy phenotypes differ in Black people with acute stroke compared to White people.

Racial disparities in the utilization and in-hospital outcomes of percutaneous left atrial appendage closure among patients with atrial fibrillation

BACKGROUND

Select patients with atrial fibrillation and contraindication to anticoagulation may benefit from percutaneous left atrial appendage closure (pLAAC).

OBJECTIVE

The purpose of this study was to evaluate racial disparities in the nationwide utilization and outcomes of pLAAC.

METHODS

We identified 16,830 hospitalizations for pLAAC between 2015 and 2017 using the National Inpatient Sample. Baseline characteristics, in-hospital mortality, complications, length of stay, and discharge disposition were assessed between White and Black/African American (AA) populations.

RESULTS

Black/AA patients represented 4.1% of nationwide pLAAC recipients and were younger, more likely to be female, and had greater prevalence of hypertension, heart failure, hyperlipidemia, obesity, chronic kidney disease, and prior stroke history (P <.001 for all). Black/AA patients had significantly increased length of stay and nonroutine discharge (P <.001 for both) but comparable in-hospital mortality to White patients. Black/AA patients suffered from greater postoperative stroke (0.7% vs 0.2%), acute kidney injury (4.5% vs 2.1%), bleeding requiring transfusion (4.5% vs 1.4%), and venous thromboembolism (0.7% vs 0.1%; P <.01 for all). After controlling for possible confounding factors, Black/AA race was independently associated with significantly increased odds of bleeding requiring blood transfusion, stroke, venous thromboembolism, and nonroutine discharge.

CONCLUSION

Among pLAAC recipients nationwide, Black/AA populations were underrepresented and had greater complication rates, length of stay, and discharge complexity. This study highlights the importance of addressing ongoing racial disparities in both utilization and outcomes of pLAAC.

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.

Global variations in the prevalence, treatment, and impact of atrial fibrillation in a multi-national cohort of 153 152 middle-aged individuals

AIMS

To compare the prevalence of electrocardiogram (ECG)-documented atrial fibrillation (or flutter) (AF) across eight regions of the world, and to examine antithrombotic use and clinical outcomes.

METHODS AND RESULTS

Baseline ECGs were collected in 153 152 middle-aged participants (ages 35-70 years) to document AF in two community-based studies, spanning 20 countries. Medication use and clinical outcome data (mean follow-up of 7.4 years) were available in one cohort. Cross-sectional analyses were performed to document the prevalence of AF and medication use, and associations between AF and clinical events were examined prospectively. Mean age of participants was 52.1 years, and 57.7% were female. Age and sex-standardized prevalence of AF varied 12-fold between regions; with the highest in North America, Europe, China, and Southeast Asia (270-360 cases per 100 000 persons); and lowest in the Middle East, Africa, and South Asia (30-60 cases per 100 000 persons) (P < 0.001). Compared with low-income countries (LICs), AF prevalence was 7-fold higher in middle-income countries (MICs) and 11-fold higher in high-income countries (HICs) (P < 0.001). Differences in AF prevalence remained significant after adjusting for traditional AF risk factors. In LICs/MICs, 24% of participants with AF and a CHADS2 score ≥1 received antithrombotic therapy, compared with 85% in HICs. AF was associated with an increased risk of stroke [hazard ratio (HR) 2.29; 95% confidence interval (CI) 1.49-3.52] and death (HR 2.97; 95% CI 2.25-3.93); with similar rates in different countries grouped by income level.

CONCLUSIONS

Large variations in AF prevalence occur in different regions and countries grouped by income level, but this is only partially explained by traditional AF risk factors. Antithrombotic therapy is infrequently used in poorer countries despite the high risk of stroke associated with AF.

Risk of Atrial Fibrillation in Black Versus White Medicare Beneficiaries With Implanted Cardiac Devices

Background

Black individuals in the United States experience higher rates of ischemic stroke than other racial groups but have lower rates of clinically apparent atrial fibrillation (AF). It is unclear whether blacks truly have less AF or simply more undiagnosed AF.

Methods and Results

We performed a retrospective cohort study using inpatient and outpatient claims from 2009 to 2015 for a 5% nationally representative sample of Medicare beneficiaries. We included patients aged ≥66 years with at least 1 documented Current Procedural Terminology code for interrogation of an implantable pacemaker, cardioverter‐defibrillator, or loop recorder and no documented history of AF, atrial flutter, or stroke before their first device interrogation. Kaplan–Meier statistics and Cox proportional hazards models were used to examine the association between black race and the composite outcome of AF or atrial flutter while adjusting for age, sex, and vascular risk factors. Among 47 417 eligible patients, the annual incidence of AF/atrial flutter was 12.2 (95% CI, 11.5–13.1) per 100 person‐years among blacks and 17.6 (95% CI, 17.4–17.9) per 100 person‐years among non‐black beneficiaries. After adjustment for confounders, black beneficiaries faced a lower hazard of AF/atrial flutter than non‐black beneficiaries (hazard ratio, 0.75; 95% CI, 0.70–0.80). Despite the lower risk of AF, black patients faced a higher hazard of ischemic stroke (hazard ratio, 1.37; 95% CI, 1.22–1.53).

Conclusions

Among Medicare beneficiaries with implanted cardiac devices capable of detecting atrial rhythm, black patients had a lower incidence of AF despite a higher burden of vascular risk factors and a higher risk of stroke.

Differences by Race/Ethnicity in the Prevalence of Clinically Detected and Monitor-Detected Atrial Fibrillation: MESA

BACKGROUND

African Americans are consistently found to have a lower prevalence of clinically detected atrial fibrillation (AF) than whites, despite a higher prevalence of major AF risk factors and higher risk of ischemic stroke. Long-term ambulatory ECG monitors provide the opportunity for unbiased AF detection. We determined differences by race/ethnicity in the prevalence of clinically detected AF and in the proportion with monitor-detected AF.

METHODS

We conducted a cross-sectional analysis in the MESA (Multi-Ethnic Study of Atherosclerosis), a community-based cohort study that enrolled 6814 Americans free of clinically recognized cardiovascular disease in 2000 to 2002. At the 2016 to 2018 examination, 1556 individuals participated in an ancillary study involving ambulatory ECG monitoring and had follow-up for clinically detected AF since cohort entry.

RESULTS

Among 1556 participants, 41% were white, 25% African American, 21% Hispanic, and 14% Chinese; 51% were women; and the mean age was 74 years. The prevalence of clinically detected AF after 14.4 years' follow-up was 11.3% in whites, 6.6% in African Americans, 7.8% in Hispanics, and 9.9% in Chinese and was significantly lower in African Americans than in whites, in both unadjusted and risk factor-adjusted analyses (adjusted rate difference, -6.6% [95% CI, -10.1% to -3.1%]; P<0.001). By contrast, in the same individuals, the proportion with monitor-detected AF using a 14-day ambulatory ECG monitor was similar in the 4 race/ethnic groups: 7.1%, 6.4%, 6.9%, and 5.2%, respectively (compared with whites, all P>0.5).

CONCLUSIONS

The prevalence of clinically detected AF was substantially lower in African American than in white participants, without or with adjustment for AF risk factors. However, unbiased AF detection by ambulatory monitoring in the same individuals revealed little difference in the proportion with AF by race/ethnicity. These findings provide support for the hypothesis of differential detection by race/ethnicity in the clinical recognition of AF, which may have important implications for stroke prevention.

The prevalence of atrial fibrillation on 48-hour ambulatory electrocardiography in African Americans compared to Whites: The Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

A lower prevalence of atrial fibrillation (AF), but paradoxically higher burden of cardiovascular disease risk factors, has been observed among African Americans compared to Whites in studies of AF identified by mostly 12-lead electrocardiograms (ECGs) and clinically.

METHODS

We performed 48-hour ambulatory electrocardiography (aECG) in a biracial sample of 1,193 participants in the Atherosclerosis Risk in Communities (ARIC) (mean age = 78 years, 62% African Americans, 64% female). Atrial fibrillation was identified from aECG, study visit ECGs, and discharge codes from cohort hospitalizations. We used covariate-adjusted logistic regression to estimate prevalence odds ratios (ORs) for AF in African Americans versus Whites, with adjustment for sampling and nonresponse.

RESULTS

African Americans were more likely than Whites to have hypertension and diabetes but less likely to have coronary heart disease. The prevalence of AF detected by aECG or ARIC study ECG (adjusted for age and coronary heart disease) was lower in African Americans than Whites (2.7% vs 5.0%). White men had a higher (although not significant) AF prevalence of 7.8% compared to the other race and gender groups at 2.3%-2.8%. The adjusted OR for AF was 0.49 (0.24-0.99) comparing African Americans to Whites. Findings were similar when AF was defined to include prior AF hospitalizations (OR = 0.42, 0.25-0.72). There were no significant differences by race for asymptomatic or paroxysmal AF.

CONCLUSIONS

Atrial fibrillation was less prevalent in African American than white older adults, regardless of detection method. Although overall detection of new AF cases with aECG was low, future studies should consider longer-term monitoring to characterize AF by race.

GWAS contribution to atrial fibrillation and atrial fibrillation-related stroke: pathophysiological implications

Atrial fibrillation (AF) and stroke are included in a group of complex traits that have been approached regarding of their study by susceptibility genetic determinants. Since 2007, several genome-wide association studies (GWAS) aiming to identify genetic variants modulating AF risk have been conducted. Thus, 11 GWAS have identified 26 SNPs (p < 5 × 10^-2), of which 19 reached genome-wide significance (p < 5 × 10^-8). From those variants, seven were also associated with cardioembolic stroke and three reached genome-wide significance in stroke GWAS. These associations may shed a light on putative shared etiologic mechanisms between AF and cardioembolic stroke. Additionally, some of these identified variants have been incorporated in genetic risk scores in order to elucidate new approaches of stroke prediction, prevention and treatment.

Racial and ethnic differences in the prevalence, management, and outcomes in patients with atrial fibrillation: A systematic review

Atrial fibrillation (AF) is the most common cardiac arrhythmia in the United States and is associated with increased morbidity, mortality, and health care expenditures. In this review, our aim was to assess the racial and ethnic differences in the epidemiology, management, and outcomes of patients with AF. A search of relevant studies from January 1, 2007, to December 30, 2017, was conducted in PubMed, EMBASE, and Web of Science and supplemented by manual searches of the bibliographies of retrieved articles. We identified 152 studies of which 64 were subsequently included. We found that underrepresented racial and ethnic groups have a higher prevalence of established risk factors associated with the development of AF but an overall lower incidence and prevalence of AF as compared with non-Hispanic whites. Moreover, racial and ethnic differences exist in detection, awareness, and AF-associated symptoms. Nonwhite populations also experience decreased use of rhythm control modalities and anticoagulation for stroke prevention. Lastly, among those with AF, underrepresented racial and ethnic groups had increased morbidity and mortality relative to white groups. Racial and ethnic differences exist in the prevalence, quality of life, management, and outcomes of individuals with AF; however, the mechanisms for these differences have yet to be fully elucidated. Racial and ethnic differences in AF warrant further analysis to understand the factors contributing to the differences in prevalence and management to ensure the delivery of high quality care that prevents stroke, reduces deaths, and decreases expenses associated with caring for underrepresented populations with AF.

Burden of Atrial Fibrillation-Associated Ischemic Stroke in the United States

OBJECTIVES

This study aimed to investigate whether the excess morbidity and mortality of atrial fibrillation (AF)-related stroke persists in the contemporary era.

BACKGROUND

Acute ischemic stroke (AIS) in patients with AF is associated with worse outcomes than in patients without AF. Stroke prevention strategies in patients with AF have improved over the last decade and AIS-related mortality overall has also declined.

METHODS

Patients ≥18 years of age who were admitted with AIS between 2003 and 2014 were identified in the National Inpatient Sample. The study compared crude and propensity score-matched in-hospital morbidity and mortality, cost, length of stay, and discharge dispositions between patients with and without AF.

RESULTS

A total of 930,010 patients were admitted with AIS, and 18.2% of these patients had AF. The prevalence of AF in these patients increased from 16.4% in 2003 to 20.4% in 2014, with the greatest increase observed in white and older patients. Propensity score matching attained 2 pairs of 125,203 patients with AIS with and without AF. In these matched cohorts, the mortality rate was higher in patients with AF (9.9% vs. 6.1%; p < 0.001). Ischemic stroke in patients with AF was also associated with higher incidences of acute kidney injury, bleeding and infectious complications, and severe disability. Hospital length of stay was significantly longer, and cost of care was 20% higher in patients with AF.

CONCLUSIONS

The prevalence of AF in AIS patients continued to rise, particularly in white and older patients. Despite the improvement in AIS-related morality overall, the differential negative impact of AF on the morbidity, mortality, and cost of AIS was steady over the study's 12-year period.

High Incidence of Occult Atrial Fibrillation in Asian Patients with Cryptogenic Stroke

BACKGROUND

Occult atrial fibrillation (AF) is not uncommon in patients with stroke. In western cohorts, insertable loop recorders (ILRs) have been shown to be the gold-standard and are cost-effective for AF detection. Anticoagulation for secondary stroke prevention is indicated if AF is detected. The incidence of occult AF among Asian patients with cryptogenic stroke is unclear.

METHODS

Patients with cryptogenic stroke referred between August 2014 and February 2017 had ILRs implanted. Episodes of AF >2 minutes duration were recorded using proprietary algorithms within the ILRs, whereupon clinicians and patients were alerted via remote monitoring. All AF episodes were adjudicated using recorded electrograms. Once AF was detected, patients were counseled for anticoagulation.

RESULTS

Seventy-one patients with cryptogenic stroke, (age 61.9 ± 13.5 years, 77.5% male, mean CHA₂DS₂VASc score of 4.2 ± 1.3) had ILRs implanted. Time from stroke to the ILR implant was a median of 66 days. Duration of ILR monitoring was 345 ± 229 days. The primary endpoint of AF detection at 6 months was 12.9%; and at 12 months it was 15.2%. Median time to detection of AF was 50 days. The AF episodes were all asymptomatic and lasted a mean of 77 minutes (± 118.9). Anticoagulation was initiated in all but 1 patient found to have AF.

CONCLUSIONS

The incidence of occult AF is high in Asian patients with cryptogenic stroke and comparable to western cohorts. The combination of ILR and remote monitoring is a highly automated, technologically driven, and clinically effective technique to screen for AF.

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.

Use of Mobile Devices to Measure Outcomes in Clinical Research, 2010-2016: A Systematic Literature Review

Background

The use of mobile devices in clinical research has advanced substantially in recent years due to the rapid pace of technology development. With an overall aim of informing the future use of mobile devices in interventional clinical research to measure primary outcomes, we conducted a systematic review of the use of and clinical outcomes measured by mobile devices (mobile outcomes) in observational and interventional clinical research.

Method

We conducted a PubMed search using a range of search terms to retrieve peer-reviewed articles on clinical research published between January 2010 and May 2016 in which mobile devices were used to measure study outcomes. We screened each publication for specific inclusion and exclusion criteria. We then identified and qualitatively summarized the use of mobile outcome assessments in clinical research, including the type and design of the study, therapeutic focus, type of mobile device(s) used, and specific mobile outcomes reported.

Results

The search retrieved 2,530 potential articles of interest. After screening, 88 publications remained. Twenty-five percent of the publications (n = 22) described mobile outcomes used in interventional research, and the rest (n = 66) described observational clinical research. Thirteen therapeutic areas were represented. Five categories of mobile devices were identified: (1) inertial sensors, (2) biosensors, (3) pressure sensors and walkways, (4) medication adherence monitors, and (5) location monitors; inertial sensors/accelerometers were most common (reported in 86% of the publications). Among the variety of mobile outcomes, various assessments of physical activity were most common (reported in 74% of the publications). Other mobile outcomes included assessments of sleep, mobility, and pill adherence, as well as biomarkers assessed using a mobile device, including cardiac measures, glucose, gastric reflux, respiratory measures, and intensity of head-related injury.

Conclusion

Mobile devices are being widely used in clinical research to assess outcomes, although their use in interventional research to assess therapeutic effectiveness is limited. For mobile devices to be used more frequently in pivotal interventional research – such as trials informing regulatory decision-making – more focus should be placed on: (1) consolidating the evidence supporting the clinical meaningfulness of specific mobile outcomes, and (2) standardizing the use of mobile devices in clinical research to measure specific mobile outcomes (e.g., data capture frequencies, placement of device). To that aim, this manuscript offers a broad overview of the various mobile outcome assessments currently used in observational and interventional research, and categorizes and consolidates this information for researchers interested in using mobile devices to assess outcomes in interventional research.

Influence of ethnic background on left atrial markers of inflammation, endothelial function and tissue remodelling

BACKGROUND

It has been suggested that ethnicity can make a significant difference to the likelihood of thromboembolic stroke related to atrial fibrillation. Ethnic differences have been shown to alter inflammatory and haemostatic factors; however, this may all be confounded by differences in cardiovascular risk factors between different ethnicity. The impact of different ethnicities on the thrombogenic profile is not known. The aim of this study was to investigate differences in markers of inflammation, endothelial function and tissue remodelling between Caucasian and Indian populations with supraventricular tachycardia (SVT).

METHODS

Patients with structurally normal hearts undergoing catheter ablation for SVT were studied. This study included 23 Australian (Caucasian) patients from the Royal Adelaide Hospital, Adelaide, Australia and 24 Indian (Indian) patients from the Christian Medical College, Vellore, India. Blood samples were collected from the femoral vein, and right and left atria. Blood samples were analysed for the markers of endothelial function (ADMA, ET-1), inflammation (CD40L, VCAM-1, ICAM-1), and tissue remodelling (MMP-9, TIMP-1) using ELISA.

RESULTS

The study populations were well matched for cardiovascular risk factors and the absence of structural heart disease. No difference in the echocardiographic measurements between the two ethnicities was found. In this context, there was no difference in markers of inflammation, endothelial function or tissue remodelling between the two SVT populations.

CONCLUSION

Caucasian and Indian populations demonstrate similar inflammatory, endothelial function or tissue remodelling profiles. This study suggests a lack of an impact of different ethnicity in these populations in terms of thrombogenic risk.

Epidemiology of Atrial Fibrillation: The Australian and Asia-Pacific Perspective

The epidemic of atrial fibrillation (AF) is increasingly recognised as a growing health problem worldwide. Although epidemiological studies on AF in the Asia-Pacific region are scarce, given the increasing age and size of populations in this region, the burden of AF is expected to be far greater than in North America and Europe. This is not only due to the growing, ageing population but also an increased incidence of risk factors for AF, such as hypertension, obesity, metabolic syndrome and diabetes, in the Asia-Pacific region. While further, high quality data on such aspects as risk factors, racial disparities and clinical implications is urgently required, there is an immediate need for increased focus on appropriate stroke prophylaxis and risk factor management to minimise the clinical complications and societal burden of AF.

Efficacy and safety of dabigatran, rivaroxaban, and warfarin for stroke prevention in Chinese patients with atrial fibrillation: the Hong Kong Atrial Fibrillation Project

BACKGROUND

Little is known about the comparative effectiveness and safety of non-vitamin K antagonist oral anticoagulants (NOAC) compared to warfarin in Chinese atrial fibrillation (AF) patients. Our aim was to compare the ischemic stroke risk reduction and incidence of intracranial hemorrhage (ICH) of warfarin in relation to quality of anticoagulation control (as reflected by time in therapeutic range [TTR]), and to dabigatran and rivaroxaban in a real-world cohort of Chinese AF patients.

HYPOTHESIS

NOAC, rather than warfarin, is preferred in Chinese AF patients.

METHODS

Of 2099 patients studied (73.1 ± 12.3 years, female: 44.6%, CHA₂ DS₂ -VASc 3.7 ± 1.9 and HAS-BLED 2.0 ± 1.0) with nonvalvular AF, 963 patients (45.9%) were on warfarin (only 16.3% had TTR ≥65%), 669 patients were on rivaroxaban, and 467 patients were on dabigatran.

RESULTS

After a mean follow-up of 21.7 ± 13.4 months, there were 156 ischemic strokes (annual incidence of 4.10%/year), with the incidence of ischemic stroke being highest in patients on warfarin with TTR <65% (5.24%/year), followed by those on rivaroxaban (3.74%/year), and those on warfarin with TTR ≥65% (3.35%/year), whereas patients on dabigatran had the lowest incidence of ischemic stroke (1.89%/year). The incidence of ICH was lowest in patients on dabigatran (0.39%/year) compared with those on rivaroxaban (0.52%/year) and warfarin, with TTR <65% (0.95%/year) and TTR ≥65% (0.58%/year). Patients on rivaroxaban 20 mg daily had similar ischemic stroke risk (1.93%/year) and ICH risk (0.21%/year) compared to dabigatran.

CONCLUSIONS

In Chinese AF patients, the benefits of warfarin therapy for stroke prevention and ICH reduction depend on TTR. Of the treatments compared, dabigatran, as well as rivaroxaban 20 mg daily, was associated with lowest ischemic stroke and ICH rates.

Racial and ethnic differences in atrial fibrillation risk factors and predictors in women: Findings from the Women's Health Initiative

BACKGROUND

The incidence of atrial fibrillation (AF) is higher in non-Hispanic whites (NHWs) compared with other race-ethnic groups, despite more favorable cardiovascular risk profiles. To explore reasons for this paradox, we compared the hazards of AF from traditional and other risk factors between 4 race-ethnic groups in a large cohort of postmenopausal women.

METHODS

We included 114,083 NHWs, 11,876 African Americans, 5,174 Hispanics, and 3,803 Asians from the Women's Health Initiative free of AF at baseline. Women, averaging 63 years old, were followed up for incident AF using hospitalization records and diagnostic codes from Medicare claims.

RESULTS

Over a mean of 13.7 years, 19,712 incident cases of AF were recorded. Despite a higher burden of hypertension, diabetes, and obesity, annual AF incidence was lower among nonwhites (0.7%, 0.4%, and 0.4% for African American, Hispanic, and Asian participants, respectively, compared with 1.2% for NHWs). The hazards of AF from hypertension, diabetes, obesity, heart failure, and coronary artery disease were similar across race-ethnic groups. Major risk factors, including hypertension, obesity, diabetes, smoking, peripheral arterial disease, coronary artery disease, and heart failure, accounted for an attributable risk of 50.3% in NHWs, 83.1% in African Americans, 65.6% in Hispanics, and 37.4% in Asians. Established AF prediction models performed comparably across race-ethnic groups.

CONCLUSIONS

In this large study of postmenopausal women, traditional cardiovascular risk factors conferred a similar degree of individual risk of AF among 4 race-ethnic groups. However, major AF risk factors conferred a higher-attributable risk in African Americans and Hispanics compared with NHWs and Asians.

Differences in the distribution of stroke subtypes in a UK black stroke population - final results from the South London Ethnicity and Stroke Study

BACKGROUND

Stroke incidence is increased in Black individuals but the reasons for this are poorly understood. Exploring the differences in aetiological stroke subtypes, and the extent to which they are explained by conventional and novel risk factors, is an important step in elucidating the underlying mechanisms for this increased stroke risk.

METHODS

Between 1999 and 2010, 1200 black and 1200 white stroke patients were prospectively recruited from a contiguous geographical area in South London in the UK. The Trial of Org 10172 (TOAST) classification was used to classify stroke subtype. Age- and sex-adjusted comparisons of socio-demographics, traditional vascular risk factors and stroke subtypes were performed between black and white stroke patients and between Black Caribbean and Black African stroke patients using age-, sex-, and social deprivation-adjusted univariable and multivariable logistic regression analyses.

RESULTS

Black stroke patients were younger than white stroke patients (mean (SD) 65.1 (13.7) vs. 74.8 (13.7) years). There were significant differences in the distribution of stroke subtypes. Small vessel disease stroke was increased in black patients versus white patients (27 % vs. 12 %; OR, 2.74; 95 % CI, 2.19-3.44), whereas large vessel and cardioembolic stroke was less frequent in black patients (OR, 0.59; 95 % CI, 0.45-0.78 and OR, 0.61; 95 % CI, 0.50-0.74, respectively). These associations remained after controlling for traditional vascular risk factors and socio-demographics. Black Caribbean patients appeared to have an intermediate risk factor and stroke subtype profile between that found in Black African and white stroke patients. Cardioembolic stroke was more strongly associated with Black Caribbean ethnicity versus Black African ethnicity (OR, 1.48; 95 % CI, 1.04-2.10), whereas intracranial large vessel disease was less frequent in Black Caribbean patients versus Black African subjects (OR, 0.44; 95 % CI, 0.24-0.83).

CONCLUSIONS

Clear differences exist in stroke subtype distribution between black and white stroke patients, with a marked increase in small vessel stroke. These could not be explained by differences in the assessed traditional risk factors. Possible explanations for these differences might include variations in genetic susceptibility, differing rates of control of vascular risk factors, or as yet undetermined environmental risk factors.

Racial Differences in the Prevalence and Outcomes of Atrial Fibrillation in Patients Hospitalized With Heart Failure

Previous research has shown that roughly 15% to 30% of those with heart failure (HF) develop atrial fibrillation (AF). Although studies have shown variations in the incidence of AF in patients with HF, there has been no evidence of mortality differences by race. The purpose of this study was to assess AF prevalence and inhospital mortality in patients with HF among different racial groups in the United States. Using the National Inpatient Sample registry, the largest publicly available all-payer inpatient care database representing >95% of the US inpatient population, we analyzed subjects hospitalized with a primary diagnosis of HF from 2001 to 2011 (n = 11,485,673) using the International Classification of Diseases, Ninth Edition (ICD 9) codes 428.0-0.1, 428.20-0.23, 428.30-0.33, 428.40-0.43, and 428.9; patients with AF were identified using the ICD 9 code 427.31. We assessed prevalence and mortality among racial groups. Using logistic regression, we examined odds of mortality adjusted for demographics and co-morbidity using Elixhauser co-morbidity index. We also examined utilization of procedures by race. Of the 11,485,673 patients hospitalized with HF in our study, 3,939,129 (34%) had AF. Patients with HF and AF had greater inhospital mortality compared with those without AF (4.6% vs 3.3% respectively, p <0.0001). Additionally, black, Hispanic, Asian, and white patients with HF and AF had a 24%, 17%, 13%, and 6% higher mortality, respectively, than if they did not have AF. Among patients with HF and AF, minority racial groups had underutilization of catheter ablation and cardioversion compared with white patients. In conclusion, minority patients with HF and AF had a disproportionately higher risk of inpatient death compared with white patients with HF. We also found a significant underutilization of cardioversion and catheter ablation in minority racial groups compared with white patients.

Rates of Atrial Fibrillation in Black Versus White Patients With Pacemakers

BACKGROUND

Black US residents experience higher rates of ischemic stroke than white residents but have lower rates of clinically apparent atrial fibrillation (AF), a strong risk factor for stroke. It is unclear whether black persons truly have less AF or simply more undiagnosed AF.

METHODS AND RESULTS

We obtained administrative claims data from state health agencies regarding all emergency department visits and hospitalizations in California, Florida, and New York. We identified a cohort of patients with pacemakers, the regular interrogation of which reduces the likelihood of undiagnosed AF. We compared rates of documented AF or atrial flutter at follow-up visits using Kaplan-Meier survival statistics and Cox proportional hazards models adjusted for demographic characteristics and vascular risk factors. We identified 10 393 black and 91 380 white patients without documented AF or atrial flutter before or at the index visit for pacemaker implantation. During 3.7 (±1.8) years of follow-up, black patients had a significantly lower rate of AF (21.4%; 95% CI 19.8-23.2) than white patients (25.5%; 95% CI 24.9-26.0). After adjustment for demographic characteristics and comorbidities, black patients had a lower hazard of AF (hazard ratio 0.91; 95% CI 0.86-0.96), a higher hazard of atrial flutter (hazard ratio 1.29; 95% CI 1.11-1.49), and a lower hazard of the composite of AF or atrial flutter (hazard ratio 0.94; 95% CI 0.88-99).

CONCLUSIONS

In a population-based sample of patients with pacemakers, black patients had a lower rate of AF compared with white patients. These findings indicate that the persistent racial disparities in rates of ischemic stroke are likely to be related to factors other than undiagnosed AF.

Electrocardiographic Left Atrial Abnormality and Risk of Stroke: Northern Manhattan Study

BACKGROUND AND PURPOSE

Electrocardiographic left atrial abnormality has been associated with stroke independently of atrial fibrillation (AF), suggesting that atrial thromboembolism may occur in the absence of AF. If true, we would expect an association with cryptogenic or cardioembolic stroke rather than noncardioembolic stroke.

METHODS

We conducted a case-cohort analysis in the Northern Manhattan Study, a prospective cohort study of stroke risk factors. P-wave terminal force in lead V1 was manually measured from baseline ECGs of participants in sinus rhythm who subsequently had ischemic stroke (n=241) and a randomly selected subcohort without stroke (n=798). Weighted Cox proportional hazard models were used to examine the association between P-wave terminal force in lead V1 and stroke etiologic subtypes while adjusting for baseline demographic characteristics, history of AF, heart failure, diabetes mellitus, hypertension, tobacco use, and lipid levels.

RESULTS

Mean P-wave terminal force in lead V1 was 4452 (±3368) μV*ms among stroke cases and 3934 (±2541) μV*ms in the subcohort. P-wave terminal force in lead V1 was associated with ischemic stroke (adjusted hazard ratio per SD, 1.20; 95% confidence interval, 1.03-1.39) and the composite of cryptogenic or cardioembolic stroke (adjusted hazard ratio per SD, 1.31; 95% confidence interval, 1.08-1.58). There was no definite association with noncardioembolic stroke subtypes (adjusted hazard ratio per SD, 1.14; 95% confidence interval, 0.92-1.40). Results were similar after excluding participants with a history of AF at baseline or new AF during follow-up.

CONCLUSIONS

ECG-defined left atrial abnormality was associated with incident cryptogenic or cardioembolic stroke independently of the presence of AF, suggesting atrial thromboembolism may occur without recognized AF.

Effect of race on outcomes (stroke and death) in patients >65 years with atrial fibrillation

Atrial fibrillation (AF) is associated with stroke and death. We sought to determine whether there are any racial differences in the outcomes of death and stroke in patients with AF. We used Medicare administrative data from January 1, 2010, to December 31, 2011, to identify 517,941 patients with newly diagnosed AF. Of these, 452,986 patients (87%) were non-Hispanic white, 36,425 (7%) were black, and 28,530 (6%) were Hispanic. The association between race and outcomes of death and stroke were measured using Cox proportional hazard models. Over a median follow-up period of 20.3 months, blacks had a significantly higher hazard of death (hazard ratio [HR] = 1.46; 95% confidence interval [CI] 1.43 to 1.48; p <0.001) and stroke (HR = 1.66; 95% CI 1.57 to 1.75; p <0.001), compared with white patients. After controlling for pre-existing co-morbidities, the higher hazard of death in blacks was eliminated (HR 0.95; 95% CI 0.93 to 0.96; p <0.001) and the relative hazard of stroke was reduced (HR = 1.46; 95% CI 1.38 to 1.55; p <0.001). Similarly, Hispanics had a higher risk of death (HR = 1.11; 95% CI 1.09 to 1.14; p <0.001) and stroke (HR = 1.21; 95% CI 1.13 to 1.29; p <0.001) compared with whites. The relative hazard of death was lower in Hispanics (HR 0.82; 95% CI 0.80 to 0.84; p <0.001) compared with whites, after controlling for pre-existing co-morbidities, and the relative hazard of stroke was also attenuated (HR = 1.11; 95% CI 1.03 to 1.18; p <0.001). In conclusion, in patients >65 years with newly diagnosed AF, the risks of death and stroke are higher in blacks and Hispanics compared with whites. The increased risk was eliminated or significantly reduced after adjusting for pre-existing co-morbidities. AF may be a marker for underlying co-morbidities in black and Hispanic patients who may be at a higher mortality risk.

Mass Screening for Untreated Atrial Fibrillation: The STROKESTOP Study

BACKGROUND

The aims of the present study were to define the prevalence of untreated atrial fibrillation (AF) in a systematic screening program using intermittent ECG recordings among 75- to 76-year-old individuals and to study the feasibility of initiating protective oral anticoagulant (OAC) treatment.

METHODS AND RESULTS

Half of the 75- to 76-year-old population in 2 Swedish regions were invited to a screening program for AF. Participants without a previous diagnosis of AF underwent intermittent ECG recordings over 2 weeks. If AF was detected, participants were offered OAC. During the 28-month inclusion period, 13 331 inhabitants were invited. Of these, 7173 (53.8%) participated. Of the participants, 218 (3.0%; 95% confidence interval [CI], 2.7-3.5) were found to have previously unknown AF, and of these, AF was found in 37 (0.5% of the screened population) on their first ECG. The use of intermittent ECGs increased new AF detection 4-fold. A previous diagnosis of AF was known in 9.3% (n=666; 95% CI, 8.6-10.0). Total AF prevalence in the screened population was 12.3%. Of participants with known AF, 149 (2.1%; 95% CI, 1.8-2.4) had no OAC treatment. In total, 5.1% (95% CI, 4.6-5.7) of the screened population had untreated AF; screening resulted in initiation of OAC treatment in 3.7% (95% CI, 3.3-4.2) of the screened population. More than 90% of the participants with previously undiagnosed AF accepted initiation of OAC treatment.

CONCLUSIONS

Mass screening for AF in a 75- to 76-year-old population identifies a significant proportion of participants with untreated AF. Initiation of stroke prophylactic treatment was highly successful in individuals with newly diagnosed AF.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01593553.

Global epidemiology of atrial fibrillation

Atrial fibrillation (AF) is a major public health burden worldwide, and its prevalence is set to increase owing to widespread population ageing, especially in rapidly developing countries such as Brazil, China, India, and Indonesia. Despite the availability of epidemiological data on the prevalence of AF in North America and Western Europe, corresponding data are limited in Africa, Asia, and South America. Moreover, other observations suggest that the prevalence of AF might be underestimated-not only in low-income and middle-income countries, but also in their high-income counterparts. Future studies are required to provide precise estimations of the global AF burden, identify important risk factors in various regions worldwide, and take into consideration regional and ethnic variations in AF. Furthermore, in response to the increasing prevalence of AF, additional resources will need to be allocated globally for prevention and treatment of AF and its associated complications. In this Review, we discuss the available data on the global prevalence, risk factors, management, financial costs, and clinical burden of AF, and highlight the current worldwide inadequacy of its treatment.