Ethnic Differences in Atrial Fibrillation
Ethnic Differences in Atrial Fibrillation
Introduction: Atrial fibrillation (AF) is suggested to be less common among black and Asian individuals, which could reflect bias in symptom reporting and access to care. In the Asymptomatic AF and Stroke Evaluation in Pacemaker Patients and the AF Reduction Atrial Pacing Trial (ASSERT), patients with hypertension but no history of AF had AF recorded via an implanted pacemaker or defibrillator, thus allowing both symptomatic and asymptomatic AF incidence to be determined without ascertainment bias.
Methods and Results: The ASSERT enrolled 2,580 patients in 23 countries in North America, Europe, and Asia. AF was defined as device-recorded AF episodes >190/min, lasting either for >6 minutes or >6 hours in duration. All ethnic groups with >50 patients were enrolled. Ethnic groups studied include Europeans (n = 1900), black Africans (n = 73), Chinese (n = 89), and Japanese (n = 105) patients. Compared to Europeans, black Africans had more risk factors for AF such as heart failure (27.8 vs 14.6%) and diabetes (41.7 vs 26.3%). At 2.5 years follow-up, all 3 non-European races had a lower incidence of AF (8.3%, 10.1%, and 9.5% vs 18.0%, respectively, for AF>6 minutes, P < 0.006). When adjusted for baseline difference, Chinese had a lower incidence of AF > 6 minutes (P < 0.007), and Japanese and black Africans had a lower incidence of AF > 6 hours (P < 0.04 and P = 0.057, respectively).
Conclusions: Black Africans, Chinese, and Japanese had lower incidence of AF compared to Europeans. In the case of black Africans, this is despite an increased prevalence of AF risk factors.
Atrial fibrillation (AF) is a growing problem worldwide and a major contributor to strokes. Evidence has suggested that AF is less common among African Americans, Chinese, Japanese, and South Asians compared to European Americans. However, it is known that a significant number of AF episodes are asymptomatic, and unequal healthcare access can cause ascertainment bias. Nevertheless, despite a higher prevalence of AF risk factors in African Americans, there is a paradoxically lower incidence of manifest AF but a higher stroke rate within this group. Contemporary investigations into ethnic differences in candidate genes for AF are intensifying. Thus, studies providing strong evidence in this realm can improve the focus and understanding of this subject, particularly if performed on racially homogenous populations that are geographically isolated, using implanted cardiac devices capable of documenting subclinical AF events without ascertainment bias.
Asymptomatic AF and Stroke Evaluation in Pacemaker Patients and the AF Reduction Atrial Pacing Trial (ASSERT) enrolled 2,580 subjects with risk factors for AF but without a history of AF. In this prospective cohort study for 2.5 years, it was determined that asymptomatic atrial events with atrial rates >190/min of >6 minutes in duration increased risk of stroke 2.5-fold. This study examines any possible racial differences in AF occurrence among subjects enrolled in ASSERT.
Abstract and Introduction
Abstract
Introduction: Atrial fibrillation (AF) is suggested to be less common among black and Asian individuals, which could reflect bias in symptom reporting and access to care. In the Asymptomatic AF and Stroke Evaluation in Pacemaker Patients and the AF Reduction Atrial Pacing Trial (ASSERT), patients with hypertension but no history of AF had AF recorded via an implanted pacemaker or defibrillator, thus allowing both symptomatic and asymptomatic AF incidence to be determined without ascertainment bias.
Methods and Results: The ASSERT enrolled 2,580 patients in 23 countries in North America, Europe, and Asia. AF was defined as device-recorded AF episodes >190/min, lasting either for >6 minutes or >6 hours in duration. All ethnic groups with >50 patients were enrolled. Ethnic groups studied include Europeans (n = 1900), black Africans (n = 73), Chinese (n = 89), and Japanese (n = 105) patients. Compared to Europeans, black Africans had more risk factors for AF such as heart failure (27.8 vs 14.6%) and diabetes (41.7 vs 26.3%). At 2.5 years follow-up, all 3 non-European races had a lower incidence of AF (8.3%, 10.1%, and 9.5% vs 18.0%, respectively, for AF>6 minutes, P < 0.006). When adjusted for baseline difference, Chinese had a lower incidence of AF > 6 minutes (P < 0.007), and Japanese and black Africans had a lower incidence of AF > 6 hours (P < 0.04 and P = 0.057, respectively).
Conclusions: Black Africans, Chinese, and Japanese had lower incidence of AF compared to Europeans. In the case of black Africans, this is despite an increased prevalence of AF risk factors.
Introduction
Atrial fibrillation (AF) is a growing problem worldwide and a major contributor to strokes. Evidence has suggested that AF is less common among African Americans, Chinese, Japanese, and South Asians compared to European Americans. However, it is known that a significant number of AF episodes are asymptomatic, and unequal healthcare access can cause ascertainment bias. Nevertheless, despite a higher prevalence of AF risk factors in African Americans, there is a paradoxically lower incidence of manifest AF but a higher stroke rate within this group. Contemporary investigations into ethnic differences in candidate genes for AF are intensifying. Thus, studies providing strong evidence in this realm can improve the focus and understanding of this subject, particularly if performed on racially homogenous populations that are geographically isolated, using implanted cardiac devices capable of documenting subclinical AF events without ascertainment bias.
Asymptomatic AF and Stroke Evaluation in Pacemaker Patients and the AF Reduction Atrial Pacing Trial (ASSERT) enrolled 2,580 subjects with risk factors for AF but without a history of AF. In this prospective cohort study for 2.5 years, it was determined that asymptomatic atrial events with atrial rates >190/min of >6 minutes in duration increased risk of stroke 2.5-fold. This study examines any possible racial differences in AF occurrence among subjects enrolled in ASSERT.
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