Incident Strokes Among American Indian Individuals With Atrial Fibrillation

Neurological Care within the Indian Health Service

American Indians and Alaska Natives (AI/AN) are the Indigenous peoples of the United States. According to the U.S. Census Bureau, approximately 9.7 million people self-identified as AI/AN (alone or in combination with other races), representing 2.9% of the total U.S. population. These people represent diverse groups of discrete Tribes, each with their language, culture, and geographic home. As part of the conquest and settlement of North America, some Indigenous peoples signed treaties with the U.S. government, surrendering their lands in return for various government commitments, including health care. The Indian Health Service (IHS) was born out of these agreements. The IHS is an agency in the U.S. Department of Health and Human Services under the U.S. Public Health Service. The IHS provides a comprehensive health service delivery system for approximately 2.7 million AI/AN who belong to 574 federally recognized Tribes/nations in 37 states. The aim of this paper is to make recommendations regarding the initiation of sustainable neurology care in marginalized or underserved populations by reviewing 40 years of neurology care provision within the IHS. We will discuss (1) the IHS, (2) neurological care provided within the IHS, including midlevel provider extension of neurology care and traditional medical care, and (3) select neurological diagnoses within AI/AN populations. Marginalized populations, including those in the United States that are rural, remote, or low socioeconomic status, lack access to specialty neurology care. This includes many AI/AN. The IHS has developed novel solutions to promote specialty care, including neurology. Notably, initial IHS investments in full-time neurology providers have led to more robust neurology care, often receiving attention from university programs. This suggests that an initial investment in stable on-site full-time neurology services provides a path to potential sustainable care for marginalized populations.

Incidence of Stroke in Indigenous Populations of Countries With a Very High Human Development Index: A Systematic Review

BACKGROUND AND OBJECTIVES

Cardiovascular disease contributes significantly to disease burden among many Indigenous populations. However, data on stroke incidence in Indigenous populations are sparse. We aimed to investigate what is known of stroke incidence in Indigenous populations of countries with a very high Human Development Index (HDI), locating the research in the broader context of Indigenous health.

METHODS

We identified population-based stroke incidence studies published between 1990 and 2022 among Indigenous adult populations of developed countries using PubMed, Embase, and Global Health databases, without language restriction. We excluded non-peer-reviewed sources, studies with fewer than 10 Indigenous people, or not covering a 35- to 64-year minimum age range. Two reviewers independently screened titles, abstracts, and full-text articles and extracted data. We assessed quality using "gold standard" criteria for population-based stroke incidence studies, the Newcastle-Ottawa Scale for risk of bias, and CONSIDER criteria for reporting of Indigenous health research. An Indigenous Advisory Board provided oversight for the study.

RESULTS

From 13,041 publications screened, 24 studies (19 full-text articles, 5 abstracts) from 7 countries met the inclusion criteria. Age-standardized stroke incidence rate ratios were greater in Aboriginal and Torres Strait Islander Australians (1.7-3.2), American Indians (1.2), Sámi of Sweden/Norway (1.08-2.14), and Singaporean Malay (1.7-1.9), compared with respective non-Indigenous populations. Studies had substantial heterogeneity in design and risk of bias. Attack rates, male-female rate ratios, and time trends are reported where available. Few investigators reported Indigenous stakeholder involvement, with few studies meeting any of the CONSIDER criteria for research among Indigenous populations.

DISCUSSION

In countries with a very high HDI, there are notable, albeit varying, disparities in stroke incidence between Indigenous and non-Indigenous populations, although there are gaps in data availability and quality. A greater understanding of stroke incidence is imperative for informing effective societal responses to socioeconomic and health disparities in these populations. Future studies into stroke incidence in Indigenous populations should be designed and conducted with Indigenous oversight and governance to facilitate improved outcomes and capacity building.

REGISTRATION INFORMATION

PROSPERO registration: CRD42021242367.

Systemic infarcts among patients with atrial fibrillation

BACKGROUND

The epidemiology of atrial fibrillation (AF)-associated thromboembolic complications outside of ischemic strokes has not been thoroughly elucidated.

OBJECTIVE

The aim of this study was to describe the epidemiology of AF-associated systemic infarcts and relevant interactions by sex and race/ethnicity.

METHODS

Using the Office of Statewide Health Planning and Development, we performed a longitudinal analysis of patients aged ≥18 years who received ambulatory surgery, emergency, or inpatient medical care in California between 2005 and 2015. We determined the distribution of infarct locations and risks of systemic infarcts for patients with AF. Interaction analyses by sex and race/ethnicity were conducted.

RESULTS

Of 1,321,694 patients with AF, the average annual rate of systemic infarct was 2.1% ± 0.18% compared with 0.56% ± 0.06% in the 22,944,488 patients without AF. The increased frequency of these infarcts was observed for every body area investigated. After adjustment for potential confounders and mediators, patients with AF experienced a 45% increased risk of a systemic infarct (hazard ratio, 1.45; 95% confidence interval, 1.44-1.47; P < .001). Women, Asians, Blacks, and Hispanics each exhibited a statistically significant heightened relative risk of systemic infarcts in the presence of AF.

CONCLUSION

AF increases the risk of infarcts throughout the body. Susceptibility to these systemic infarcts varies by sex and race/ethnicity in patterns similar to differential risks for stroke. The presence of a systemic infarct in the absence of a clear cause should raise suspicion for AF, and the potential benefits of AF prevention and anticoagulation should be considered beyond only infarcts to the brain.

Is the Pattern Changing? Atrial Fibrillation and Screening with Holter Electrocardiograms among Ischemic Stroke Patients in Greenland from 2016 to 2021

A standardized examination regime for ischemic stroke (IS) patients was implemented in Greenland in 2010. Prevalence of atrial fibrillation (AF) of 32% was found among discharged IS patients from 2011 to 2012, and our study aims to estimate the use of Holter ECGs for AF diagnostics and the current prevalence of AF among IS patients in Greenland. Patients discharged from Queen Ingrid's Hospital in Nuuk between 2016 and 2021 with an ICD-10 diagnosis of IS or stroke without specification were included. Data on Holter recordings, age, gender, medical treatment with rivaroxaban or warfarin, and ICD-10 and ICPC codes for AF were extracted for each patient. The overall incidence of IS from 2016 to 2021 was 133/100,000 and unchanged since 2012. Sixty-eight of the study's IS patients (14.5%) had AF, and 46% of IS patients with Holter data accessible had a recording according to international recommendations. Our results indicate that fewer IS patients in Greenland have AF than previously. However, the insufficient use of Holter as a diagnostic tool may explain part of the drop, as well as improved preventive treatment with rivaroxaban among AF patients in Greenland. Regardless, IS remains common, and a focus on diagnostics and preventable risk factors should be maintained.

American Indians and atrial fibrillation

The American Indian population is known to experience high rates of cardiovascular disease and have a heightened vulnerability to severe outcomes driven by an overall poor health status and lower access to quality health care. Our group has previously published an analysis demonstrating that American Indians have the highest risk of atrial fibrillation (AF), as well as of AF-related stroke, when compared with other races and ethnicities. Despite this, AF in this population has not been extensively studied and additional publications are scarce. Our review article provides an up-to-date summary of the relevant literature addressing the relationship between race, ethnicity, and AF by focusing on American Indians.

Association of Race and Ethnicity With Oral Anticoagulation and Associated Outcomes in Patients With Atrial Fibrillation: Findings From the Get With The Guidelines-Atrial Fibrillation Registry

Importance

Oral anticoagulation (OAC) is underprescribed in underrepresented racial and ethnic group individuals with atrial fibrillation (AF). Little is known of how differential OAC prescribing relates to inequities in AF outcomes.

Objective

To compare OAC use at discharge and AF-related outcomes by race and ethnicity in the Get With The Guidelines-Atrial Fibrillation (GWTG-AFIB) registry.

Design, Setting, and Participants

This retrospective cohort analysis used data from the GWTG-AFIB registry, a national quality improvement initiative for hospitalized patients with AF. All registry patients hospitalized with AF from 2014 to 2020 were included in the study. Data were analyzed from November 2021 to July 2022.

Exposures

Self-reported race and ethnicity assessed in GWTG-AFIB registry.

Main Outcomes and Measures

The primary outcome was prescription of direct-acting OAC (DOAC) or warfarin at discharge. Secondary outcomes included cumulative 1-year incidence of ischemic stroke, major bleeding, and mortality postdischarge. Outcomes adjusted for patient demographic, clinical, and socioeconomic characteristics as well as hospital factors.

Results

Among 69 553 patients hospitalized with AF from 159 sites between 2014 and 2020, 863 (1.2%) were Asian, 5062 (7.3%) were Black, 4058 (5.8%) were Hispanic, and 59 570 (85.6%) were White. Overall, 34 113 (49.1%) were women; the median (IQR) age was 72 (63-80) years, and the median (IQR) CHA2DS2-VASc score (calculated as congestive heart failure, hypertension, age 75 years and older, diabetes, stroke or transient ischemic attack, vascular disease, age 65 to 74 years, and sex category) was 4 (2-5). At discharge, 56 385 patients (81.1%) were prescribed OAC therapy, including 41 760 (74.1%) receiving DOAC. OAC prescription at discharge was lowest in Hispanic patients (3010 [74.2%]), followed by Black patients (3935 [77.7%]) Asian patients (691 [80.1%]), and White patients (48 749 [81.8%]). Black patients were less likely than White patients to be discharged while taking any anticoagulant (adjusted odds ratio, 0.75; 95% CI, 0.68-0.84) and DOACs (adjusted odds ratio, 0.73; 95% CI, 0.65-0.82). In 16 307 individuals with 1-year follow up data, bleeding risks (adjusted hazard ratio [aHR], 2.08; 95% CI, 1.53-2.83), stroke risks (aHR, 2.07; 95% CI, 1.34-3.20), and mortality risks (aHR, 1.22; 95% CI, 1.02-1.47) were higher in Black patients than White patients. Hispanic patients had higher stroke risk (aHR, 2.02; 95% CI, 1.38-2.95) than White patients.

Conclusions and Relevance

In a national registry of hospitalized patients with AF, compared with White patients, Black patients were less likely to be discharged while taking anticoagulant therapy and DOACs in particular. Black and Hispanic patients had higher risk of stroke compared with White patients; Black patients had a higher risk of bleeding and mortality. There is an urgent need for interventions to achieve pharmacoequity in guideline-directed AF management to improve overall outcomes.

Demographic and Regional Trends in Stroke-Related Mortality in Young Adults in the United States, 1999 to 2019

Background Despite improvements in the management and prevention of stroke, increasing hospitalizations for stroke and stagnant mortality rates have been described in young adults. However, there is a paucity of contemporary national mortality estimates in young adults. Methods and Results Trends in mortality related to stroke in young adults (aged 25-64 years) were assessed using the Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research database. Age-adjusted mortality rates per 100 000 people with associated annual percentage change were calculated. Joinpoint regression was used to assess the trends in the overall sample and different demographic (sex, race and ethnicity, and age) and geographical (state, urban-rural, and regional) subgroups. Between 1999 and 2019, a total of 566 916 stroke-related deaths occurred among young adults. After the initial decline in mortality in the overall population, age-adjusted mortality rate increased from 2013 to 2019 with an associated annual percentage change of 1.5 (95% CI, 1.1-2.0). Mortality rates were higher in men versus women and in non-Hispanic Black people versus individuals of other races and ethnicities. Non-Hispanic American Indian or Alaskan Native people had a marked increase in stroke-related mortality (annual percentage change 2010-2019: 3.3). Furthermore, rural (nonmetropolitan) counties experienced the greatest increase in mortality (annual percentage change 2012-2019: 3.1) compared with urban (metropolitan) counties. Conclusions Following the initial decline in stroke-related mortality, young adults have experienced increasing mortality rates from 2013 to 2019, with considerable differences across demographic groups and regions.

PRRX1 Loss-of-Function Mutations Underlying Familial Atrial Fibrillation

Background

Atrial fibrillation (AF) is the most common form of clinical cardiac dysrhythmia responsible for thromboembolic cerebral stroke, congestive heart failure, and death. Aggregating evidence highlights the strong genetic basis of AF. Nevertheless, AF is of pronounced genetic heterogeneity, and in an overwhelming majority of patients, the genetic determinants underpinning AF remain elusive.

Methods and Results

By genome‐wide screening with polymorphic microsatellite markers and linkage analysis in a 4‐generation Chinese family affected with autosomal‐dominant AF, a novel locus for AF was mapped to chromosome 1q24.2–q25.1, a 3.20‐cM (≈4.19 Mbp) interval between markers D1S2851 and D1S218, with the greatest 2‐point logarithm of odds score of 4.8165 for the marker D1S452 at recombination fraction=0.00. Whole‐exome sequencing and bioinformatics analyses showed that within the mapping region, only the mutation in the paired related homeobox 1 (PRRX1) gene, NM_022716.4:c.319C>T;(p.Gln107*), cosegregated with AF in the family. In addition, sequencing analyses of PRRX1 in another cohort of 225 unrelated patients with AF revealed a new mutation, NM_022716.4:c.437G>T; (p.Arg146Ile), in a patient. The 2 mutations were absent in 908 control subjects. Biological analyses in HeLa cells demonstrated that the 2 mutants had significantly diminished transactivation on the target genes ISL1 and SHOX2 and markedly decreased ability to bind the promoters of ISL1 and SHOX2 (2 genes causally linked to AF), although with normal intracellular distribution.

Conclusions

This study first indicates that PRRX1 loss‐of‐function mutations predispose to AF, which provides novel insight into the molecular pathogenesis underpinning AF, implying potential implications for precisive prophylaxis and management of AF.

Incident Strokes Among American Indian Individuals With Atrial Fibrillation

BACKGROUND

American Indian individuals experience a relatively high risk for cardiovascular disease and have exhibited a higher risk of stroke compared with other racial and ethnic minorities. Although this population has the highest incidence of atrial fibrillation (AF) compared with other groups, the relationship between AF and nonhemorrhagic stroke among American Indian individuals compared with other groups has not been thoroughly studied.

METHODS and RESULTS

We used the Healthcare Cost and Utilization Project to evaluate risk of nonhemorrhagic stroke among American Indian individuals, with comparisons to White, Black, Hispanic, and Asian individuals, among all adult California residents receiving care in an emergency department, inpatient hospital unit, or ambulatory surgery setting from 2005 to 2011. Of 16 951 579 patients followed for a median 4.1 years, 105 822 (0.6%) were American Indian. After adjusting for age, sex, income level, insurance payer, hypertension, diabetes mellitus, coronary artery disease, congestive heart failure, cardiac surgery, valvular heart disease, chronic kidney disease, smoking, obstructive sleep apnea, pulmonary disease, and alcohol use, American Indian individuals with AF exhibited the highest risk of nonhemorrhagic stroke when compared with either non‐American Indian individuals with AF (hazard ratio, 1.38; 95% CI, 1.23–1.55; P<0.0001) or to each race and ethnicity with AF. American Indian individuals also experienced the highest overall risk for stroke, with no evidence that AF disproportionately heightened that risk in interaction analyses.

CONCLUSIONS

American Indian individuals experienced the highest risk of nonhemorrhagic stroke, whether in the presence or absence of AF. Our findings likely suggest an opportunity to further study, if not immediately address, guideline‐adherent anticoagulation prescribing patterns among American Indian individuals with AF.