Abstract P113: New-onset Atrial Fibrillation and Risk of Mortality and Cardiovascular Disease in Whites and African Americans: the ARIC Study

Abstract

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)