Abstract P111: Serum and Dietary Magnesium and the Incidence of Atrial Fibrillation in Whites and African Americans: The Atherosclerosis Risk in Communities (ARIC) Study

Background: Low serum magnesium (Mg) has been associated with a higher cardiovascular risk and other cardiovascular diseases (CVD) including ventricular arrhythmias. However, the association between serum or dietary Mg and atrial fibrillation (AF) has not been investigated to date. Methods: We studied 14,290 men and women (75% white, 53% women, mean age 54) free of AF at baseline participating in the Atherosclerosis Risk in Communities (ARIC) study, a community-based cohort in the United States. Serum Mg was assessed at baseline (1987-89) and a second visit (1990-92) while dietary Mg was assessed at baseline and a third visit (1993-95). The mean value of two Mg measurements were used for individuals who attended both visits while the baseline Mg measurement was used for individuals who did not attend another visit or were censored. Incident AF cases through 2008 were ascertained from electrocardiograms, hospital discharge codes, and death certificates. Cox proportional hazards regression was used to estimate hazard ratios and 95% confidence intervals for AF associated with serum and dietary Mg quintiles. Models were initially adjusted for age, sex, race, and ARIC field center, and additional models further adjusted for other cardiovascular risk factors and prevalent CVD. Dietary Mg analyses included correlated dietary covariates in all models. Interaction by race and sex was tested for serum and dietary Mg. Results: Over a median follow-up time of 19.7 years, 1,613 incident AF cases were identified. Higher serum Mg was associated with lower AF risk even after adjustment for cardiovascular risk factors and other CVD (table), with no evidence of significant interactions between serum Mg and sex or race. No significant association was identified between dietary Mg and AF. Conclusion: High serum Mg was associated with a lower AF risk, and this association was not different between whites and African Americans. Dietary Mg was not associated with AF risk. Funding(This research has received full or partial funding support from the American Heart Association, National Center)