What is the clinical evidence from this study?

Study design: Cohort. Population: Atrial fibrillation (n=25976). Intervention: Atrial fibrillation vs. No atrial fibrillation. Primary outcome: All-cause mortality (HR 1.32, 95% CI 1.19-1.46).

February 1, 2016Open Access

Impact of Awareness and Patterns of Nonhospitalized Atrial Fibrillation on the Risk of Mortality: The Reasons for Geographic And Racial Differences in Stroke (REGARDS) Study

Key Result

Atrial fibrillation was associated with a 32% increased risk of mortality (HR 1.32; 95% CI 1.19-1.46), with higher risk among those with ECG-detected AF and those unaware of their diagnosis.

Study Design

Type

Cohort (n=25,976)

Multicenter

Yes

Structured PICO

Does asymptomatic, nonhospitalized atrial fibrillation increase the risk of mortality in the general population?

Population

25,976 participants (mean age 65, 55% female, 38% black) from the REGARDS study followed for a median of 7.6 years.

Exposure

Presence of atrial fibrillation (detected on baseline ECG or self-reported history), specifically asymptomatic/unaware AF (ECG evidence but no self-reported history).

Comparator

Participants without atrial fibrillation, or participants aware of their AF diagnosis.

Outcome

All-cause mortality confirmed during follow-up through March 31, 2014.hard clinical

Asymptomatic, nonhospitalized atrial fibrillation, particularly when patients are unaware of the diagnosis, is associated with a significantly increased risk of mortality.

Main Result

Hazard Ratio: 1.32 (95% CI 1.19–1.46)

Abstract

BACKGROUND: Although mortality associated with atrial fibrillation (AF) has been reported to decrease over prior decades, the mortality risk of asymptomatic, nonhospitalized AF has not been examined. HYPOTHESIS: Asymptomatic, nonhospitalized AF is associated with an increased risk of death. METHODS: This analysis included 25,976 participants (mean age, 65 ± 9.4 years; 55% female; 38% black) from the Reasons for Geographic And Racial Differences (REGARDS) study. Atrial fibrillation was detected on the baseline electrocardiogram (ECG AF) or by self-reported history. Atrial fibrillation unawareness was defined as present if ECG evidence of the arrhythmia was detected but no self-reported history was reported. All-cause mortality was confirmed during follow-up through March 31, 2014. RESULTS: A total of 2208 (8.5%) participants had AF at baseline (ECG: n = 371/17%; self-reported: n = 1837/83%). Over a median follow-up of 7.6 years, 3481 deaths occurred. In a multivariable Cox regression model, AF was associated with a 32% increased risk of mortality (95% confidence interval CI: 1.19-1.46). Risk of death was higher among those with ECG AF (hazard ratio: 1.71, 95% CI: 1.42-2.07) compared with self-reported cases (hazard ratio: 1.15, 95% CI: 1.03-1.29). Those who were unaware of their AF diagnosis had a 94% increased risk of death (95% CI: 1.50-2.52) compared with AF participants who were aware of their diagnosis. CONCLUSIONS: Asymptomatic, nonhospitalized AF is associated with an increased risk of mortality in the general population. Mortality is higher in those with ECG-confirmed cases and among those who are unaware of their diagnosis.