Echocardiographic Measures of Cardiac Structure and Function Are Associated with Risk of Atrial Fibrillation in Blacks: The Atherosclerosis Risk in Communities (ARIC) Study

BackgroundSeveral studies have examined the link between atrial fibrillation (AF) and various echocardiographic measures of cardiac structure and function in whites and other racial groups but not in blacks. Exploring AF risk factors in blacks is important given that the lower incidence of AF in this racial group despite higher risk factors, is not completely explained.MethodsWe examined the association of echocardiographic measures with AF incidence in 2283 blacks (64.5% women, mean age 58.8 years) free of diagnosed AF and enrolled in the Jackson cohort of Atherosclerosis Risk in Communities (ARIC) study, a prospective study of cardiovascular disease. Echocardiography was performed in 1993–1995, and incident AF was determined by electrocardiograms at a follow-up study exam, hospitalization discharge codes and death certificates through the end of 2009. Cox proportional hazards regression was used to estimate hazard ratios and 95% confidence intervals for AF associated with the echocardiographic measures, adjusting for age, sex, and known AF risk factors.ResultsDuring an average follow-up of 13.5 years, 191 (8.4%) individuals developed AF. Left ventricular (LV) internal diameter 2-D (diastole) and percent fractional shortening of LV diameter displayed a U-shaped relationship with risk of AF, while left atrial diameter displayed a J-shaped nonlinear association. LV mass index was associated positively with AF. E/A ratio 1.5 and ejection fraction (EF <50%) were also associated with higher AF risk. These measures improved risk stratification for AF in addition to traditional risk factors, although not significantly {C-statistic of 0.767 (0.714–0.819) vs. 0.744 (0.691–0.797)}.ConclusionsIn a community-based population of blacks, echocardiographic measures of cardiac structure and function are significantly associated with an increased risk of AF

Baseline characteristics by total white blood cell (WBC) count quintile, Atherosclerosis Risk in Communities Study, 1987 to 1989.

<p>BP indicates blood pressure. Values are mean (SD) when appropriate.</p><p>*Reduced sample size: n = 10,661</p><p>†All baseline characteristics have p-values <0.05 for differences in means (ANOVA) and percentages (Chi-Square) between total WBC quintiles except for height and prevalent stroke.</p><p>Baseline characteristics by total white blood cell (WBC) count quintile, Atherosclerosis Risk in Communities Study, 1987 to 1989.</p

Association between each white blood cell differential count and incident atrial fibrillation presented as hazard ratio (solid line) and 95% confidence intervals (shaded area), Atherosclerosis Risk in Communities Study, 1987 to 2010.

<p>(A) Neutrophil Count; (B) Lymphocyte Count; (C) Neutrophil Count/Lymphocyte Count Ratio; (D) Monocyte Count; (E) Eosinophil Count. *Cox proportional hazards model using restricted cubic splines with knots at the 5^th, 27.5^th, 50^th, 72.5^th and 95^th percentiles and adjustment for age, race, and sex. The reference is the median value of each white blood cell differential count (hazard ratio = 1), and the histogram represents the frequency distribution of each white blood cell differential count in the study sample.</p

Hazard ratios (HR) and 95% confidence intervals (CI) for the association of echocardiographic parameters in quintiles with time to incident atrial fibrillation (AF), ARIC Jackson Cohort, 1993–2009.

<p><b>*</b> Linear trend in quintile number.</p>†<p>Model 1 - adjusted for age and sex.</p>‡<p>Model 2 – adjusted for Model 1 + CHARGE risk score.</p><p>Hazard ratios (HR) and 95% confidence intervals (CI) for the association of echocardiographic parameters in quintiles with time to incident atrial fibrillation (AF), ARIC Jackson Cohort, 1993–2009.</p

Baseline characteristics with incident atrial fibrillation (AF) events through 2009 follow-up, Atherosclerosis Risk in Communities Study Jackson Cohort, 1993–1995.

<p><b>* Data given as mean±SD or n (%).</b></p><p>Baseline characteristics with incident atrial fibrillation (AF) events through 2009 follow-up, Atherosclerosis Risk in Communities Study Jackson Cohort, 1993–1995.</p