Abstract P113: New-onset Atrial Fibrillation and Risk of Mortality and Cardiovascular Disease in Whites and African Americans: the ARIC Study
Authors: Alonso Alvaro , Agarwal Sunil K , Soliman Elsayed Z , Chen Lin Y , Lopez Faye L , Chamberlain Alanna M , Loehr Laura R 
Published: July 2021

Background:
Multiple studies have shown that atrial fibrillation (AF), a common cardiac arrhythmia, is associated with increased mortality and higher incidence of stroke and heart failure. However, evidence for this association in African Americans is lacking.

Methods:
We studied 4,063 African Americans and 11,280 whites in the Atherosclerosis Risk in Communities (ARIC) Study, a US community-based cohort study, aged 45-64 (55% women) and free of AF at baseline in 1987-89. Three additional follow-up exams were conducted in 1990-92, 1993-95, and 1996-98. AF was ascertained during follow-up with study visit ECGs and hospital surveillance. Mortality and incidence of stroke and heart failure were ascertained according to study protocols. Using multivariable Cox proportional hazards models with time-dependent covariates, we calculated hazard ratios (HR) and 95% confidence intervals (CI) of mortality, stroke and heart failure in those with new-onset AF compared to those without AF by race.

Results:
During an average follow-up of 18 years, 332 AF cases were ascertained in African Americans and 1407 in whites. Overall, African Americans showed higher all-cause mortality and cardiovascular disease rates than whites (
Table
). AF was associated with increased mortality and risk of incident stroke and heart failure in whites and African Americans, even after adjustment for baseline and time-dependent potential confounders (
Table
). Associations of AF with all-cause mortality and stroke were of similar magnitude in both racial groups. However, the association between AF and heart failure was stronger in whites than in African Americans (HR 3.6, 95% CI 3.1-4.2 in whites, vs. HR 2.2, 95% CI 1.6-3.0 in African Americans).

Conclusion:
New-onset AF was associated with an increased risk of all-cause mortality, stroke, and heart failure in whites and African Americans independently of other cardiovascular risk factors.

Table.

Hazard ratios (95% confidence interval) of all-cause mortality, stroke, and heart failure in those with new-onset atrial fibrillation (AF) versus those without AF by race, ARIC, 1987-2008

Blacks
Whites
P for interaction

No AF (n=3731)
AF (n=332)
No AF (n=9873)
AF (n=1407)

Mortality

Deaths (n)
1144
188
2042
630

Person-years
69,483
1268
200,878
7493

Mortality rate

1

18.6
126.3
10.1
62.3

Model 1
1 (ref.)
5.80 (4.93-6.82)
1 (ref.)
4.58 (4.17-5.04)
0.27

Model 2
1 (ref.)
3.20 (2.71-3.76)
1 (ref.)
2.87 (2.61-3.17)
0.68

Stroke

Events (n)
281
23
347
64

Person-years
51,082
867
147,608
5040

Incidence rate

1

6.0
25.0
2.4
11.5

Model 1
1 (ref.)
2.91 (1.81-4.68)
1 (ref.)
2.52 (1.86-3.43)
0.94

Model 2
1 (ref.)
1.83 (1.13-2.96)
1 (ref.)
1.91 (1.39-2.62)
0.82

Heart failure

Events
613
71
992
364

Person-years
62,570
721
187,847
4578

Incidence rate

1

10.7
108.1
5.3
76.1

Model 1
1 (ref.)
3.35 (2.41-4.65)
1 (ref.)
4.75 (4.09-5.51)
0.02

Model 2
1 (ref.)
2.18 (1.56-3.04)
1 (ref.)
3.63 (3.12-4.21)
0.0006

1

Age- and sex-standardized, per 1000 person-years;
Model 1
: Cox proportional hazards model adjusted for age, sex, and study center, with AF incidence as a time-dependent covariate;
Model 2
: As model 1, but additionally adjusting for baseline education, and time-dependent body mass index, smoking, diabetes, hypertension, stroke, heart failure, and myocardial infarction

Funding(This research has received full or partial funding support from the American Heart Association, National Center)