Published data on AF in Indigenous populations in the affluent countries included in this review are scanty, fragmentary and of varying quality, with a minority subjected to peer-review. Aside from the potential for real differences in AF epidemiology among Indigenous populations between and within countries, study comparability is limited by differences in quality, design, analytical methods (including means of identifying Indigenous subjects and covariate adjustments), setting (community versus hospital) and calendar time frame.

In consequence, the epidemiology of AF in these populations remains inadequately delineated, with no clear pattern emerging. However, both linked and unlinked administrative hospital data from Canada [28], Australia [29, 30], and NZ [39] suggest that hospitalised AF is more common at younger ages in Indigenous people, with higher first-ever AF hospitalisations in WA (notably under 65 years) and Ontario possibly reflecting disparities in population-based incidence. Concordant with these findings, small studies from Canada and NZ suggest higher AF prevalence among Métis and Māori respectively than the non-Indigenous comparator populations. In contrast, the significantly lower nationwide prevalence of AF among Native Americans than Whites reported in the US study of male military veterans, which incorporated both hospitalisation and ambulatory care data, suggest that higher AF occurrence in Indigenous populations may not apply in the US. Although no difference in short-term (30-day) post-admission mortality was found in the WA cohort, one-year mortality was higher among both WA Aboriginal patients and Ontarian Métis than among the respective comparator populations.

The major antecedents of AF traverse the ‘epidemiological transition’ [57], encompassing sequelae of infectious disease (with streptococcal infection underlying RHD) as well as non-communicable diseases (particularly hypertension and coronary atherothrombosis). As a generalisation, all of these occur in excess and at younger ages among Indigenous peoples, in both North America and Australasia [58‐62]. Accordingly, the occurrence of AF would be expected to be correspondingly increased in these populations once age has been accounted for. However, the epidemiological pattern of these disparities is complex, varying among the specific disorders as well as within and between different countries, in magnitude and secular trends. Epidemiological surveillance of Indigenous populations for these underlying disorders remains suboptimal, partly because of inadequate Indigenous identifiers in routinely collected data, particularly in North America.

Unexpectedly, studies of AF frequency among ethnic minority groups such as African Americans, Hispanics and Europeans of African, Afro-Caribbean or Indo-Asian ancestry suggest a ‘racial paradox’, i.e., that the condition is unexpectedly less common among these minority populations than Whites, despite the major risk factors generally being present in excess [63, 64]. The US study of male veterans included in this review suggests that this phenomenon may extend to Native Americans. However, the findings of this study may not be generalisable to the whole US population, insofar as military recruitment is characterised by over-representation of lower socioeconomic strata and so may be disproportionately unrepresentative of the majority ‘White’ population, with under-participation of the most affluent. Recuitment also excludes persons with certain pre-existing health problems (such as congenital or rheumatic cardiac lesions predisposing to AF) and may represent a ‘healthy worker’ effect with those of poorer health not meeting enlistment criteria. Moreover, as outlined in a review of AF and race, ‘[u]nder-ascertainment and differential mortality may partially contribute towards the apparent lower burden of AF [reported] in racial and ethnic minorities’ [63]. No other published data elucidate the relative frequency of AF in the Native American population, despite the substantial research profile of Indigenous CVD in the US, notably that arising from the Strong Heart Study cohort, ‘the largest epidemiologic study of American Indians ever undertaken’ [65].

The available evidence suggests that the ‘paradox’ does not apply to Indigenous minorities in Canada, Australia and NZ and that AF frequency is increased among the Indigenous peoples of these countries, at least at younger ages. However, in interpreting hospitalisation data upon which the largest studies are based, it is important to recognise that frequency of first hospitalisation is not equivalent to incidence rate in a population. Hospitalisations are influenced by health-seeking behaviour and the quality of health care such that disparities between ethnic groups in access to care modify the likelihood of admission. Firstly, inadequate AF management in primary care—including tardy detection—may increase the likelihood of preventable hospitalisation and also skew the spectrum of hospitalised cases towards greater severity, due to poor control of the arrhythmia or associated conditions (such as heart failure) and complications (particularly stroke). Conversely, poor access to hospital care may diminish elective admissions for AF and associated morbidities. In order to establish the true incidence rate of the condition in a population, community-based, longitudinal cohort studies incorporating active surveillance are required. No study of this kind is available for the Indigenous peoples considered.

While a focus on inequities in social determinants and service provision is necessarily paramount in explaining the poorer health of Indigenous peoples, there is a possibility of inter-ethnic variation in genetic predisposition to specific disorders. In relation to AF, a lower prevalence among African Americans compared with Caucasians, despite the more common occurrence of major risk factors in the former, appears to be partly attributable to genetic factors [64, 66]. The extent to which genetic variation modulates AF risk among diverse Indigenous peoples has not been investigated.

Disease outcome indices such as mortality and readmission rates are determined by both disease severity and quality of health service provision during and/or after hospitalisation. Rates for early mortality (30-day mortality among Western Australians following an AF admission and in-hospital mortality among US subjects admitted with AF) were not increased among Indigenous subjects, suggesting that they receive adequate in-hospital care. The data from Western Australia and Ontario reporting relatively high 1-year mortality following an AF hospitalisation could reflect greater severity of disease and/or poorer post-discharge management.

In view of the scanty data, publications were included in this review if they reported Indigenous versus non-Indigenous comparative AF frequency in specific clinical groups. The search results were dominated by these publications. Although several high quality cohort studies were identified, in most cases the principal hypotheses were unrelated to AF, and the AF data were limited to baseline crude frequencies in patient subgroups, including comparisons between Indigenous and other ethnic groups. These data add little to the picture of AF epidemiology in Indigenous populations, except that they demonstrate that AF is characteristically a subsidiary consideration in clinical research, investigated in relation to comorbidities contributing to the clinical complexity of patients rather than examined in its own right. Such data are difficult to interpret, particularly because of the potential for substantial confounding by age and severity of underlying illness. An exception was a stroke prevalence study, showing higher proportions of AF comorbidity in Aboriginal Australians at all ages under 70 years [49]. Of note, age-standardisation did not adequately correct for age differences in that study.

Optimal clinical management of AF is predicated on access to high-quality health care, in relation to which Indigenous populations in general are demonstrably disadvantaged [67, 68]. There is essentially no published evidence on equity of health services provision for AF in these populations although evidence from other cardiometabolic conditions suggests that they are likely to have higher rates of comorbidities that complicate their condition and management [69]. Besides the Ontario paper’s crude comparison of receipt of echocardiography [31], our literature search identified a near absence of data on AF management in Indigenous people. In the broader population, barriers to optimal therapy of AF include underdiagnosis, underestimation of its prognostic severity, inadequate implementation of evidence-based therapeutic guidelines, limited access to care, and inadequate adherence to prescribed treatment [70]. These barriers are likely to be amplified among disadvantaged, marginalised groups such as Indigenous people [71]. AF is especially susceptible to under-diagnosis, given its propensity to be asymptomatic or to manifest with non-specific features, with a substantial proportion of strokes attributable to unrecognised AF [72]. Of particular concern are the many undiagnosed AF patients for whom long-term anticoagulant medication is necessary in order to prevent thromboembolic disease. Notably, since our literature search was performed, a large single-institution South Australian series of patients with known AF (n = 19613 patients; 308 Indigenous) documented that guideline-determined underuse and overuse of anticoagulant medications were both significantly more common (ORs 1.27 and 1.60 respectively) among Indigenous than non-Indigenous patients [73]. In general terms, the socio-economic and environmental factors predisposing Indigenous peoples to conditions associated with AF are also likely to compromise its clinical management [74].

This scoping review contributes to a genre that brings together research on the health of Indigenous minorities living in affluent countries [8, 75‐78]. Its strengths include an exhaustive search of established databases, efforts to access the grey literature and appraisal of study quality to provide an overview of existing research into AF in Indigenous peoples of the selected countries. The principal limitation of the review was the need to frame its design as a scoping study without a focussed research question, based on anticipation of scanty published data. Furthermore, there are unavoidable trade-offs in the exhaustive approach to literature searching that extends beyond indexed academic databases. Although Google Scholar allows searching the full text of publications, thereby allowing recognition of data that may not be identified through subject headings keywords, titles and abstracts, this interface has less sophisticated functionality for systematic searching than traditional databases [79]. Furthermore, the ‘grey’ literature such as government websites is characterised by inconsistent quality by virtue of the absence of peer review, as well as poor searchability given the diversity of formats, the absence of controlled vocabulary indexing, and sheer volume [80]. The NOS used to appraise the quality of studies of non-randomised design is limited by subjectivity, as demonstrated by high inter-observer variation [81].