Serum and dietary magnesium and incidence of atrial fibrillation in whites and in African Americans--Atherosclerosis Risk in Communities (ARIC) study

Abstract

Background: Low serum magnesium (Mg) has been associated with an increased risk of cardiovascular disease (CVD), including ventricular arrhythmias, but the association between serum or dietary Mg and atrial fibrillation (AF) has not been investigated.

Methods and results: A total of 14,290 men and women (75% white; 53% female; mean age, 54 years) free of AF at baseline participating in the Atherosclerosis Risk in Communities study in the United States, were studied. Incident AF cases through 2009 were ascertained from electrocardiograms, hospital discharge codes, and death certificates. Multivariate Cox proportional hazards regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for AF associated with serum and dietary Mg quintiles. Over a median follow-up time of 20.6 years, 1,755 incident AF cases were identified. In multivariate models, lower serum Mg was associated with higher AF risk: compared to individuals in the middle quintile (≥ 0.80-0.83 mmol/L), the HR (95% CI) of AF in quintiles 1, 2, 4, and 5 were 1.34 (1.16-1.54), 0.99 (0.85-1.16), 1.04 (0.90-1.22), and 1.06 (0.91-1.23), respectively. There was no evidence of significant interactions between serum Mg and sex or race. No association between dietary Mg and AF risk was observed.

Conclusions: Lower serum Mg was associated with a higher AF risk, and this association was not different between whites and African Americans. Dietary Mg was not associated with AF risk.

Figure 1

Association between serum magnesium quintile and atrial fibrillation stratified by sex, Atherosclerosis Risk in Communities, 1987 to 2009. *Cox proportional hazards model adjusted for age, sex, race, study site, body mass index, high density lipoprotein cholesterol, low density lipoprotein cholesterol, serum potassium, serum creatinine, smoking status, drinking status, educational level, systolic blood pressure, diabetes, antihypertensive medication, and prevalent myocardial infarction, heart failure, or stroke. †The reference group is the third serum magnesium quintile.

Figure 2

Association between serum magnesium quintile and atrial fibrillation stratified by race, Atherosclerosis Risk in Communities, 1987 to 2009. *Cox proportional hazards model adjusted for age, sex, race, study site, body mass index, high density lipoprotein cholesterol, low density lipoprotein cholesterol, serum potassium, serum creatinine, smoking status, drinking status, educational level, systolic blood pressure, diabetes, antihypertensive medication, and prevalent myocardial infarction, heart failure, or stroke. †The reference group is the third serum magnesium quintile. ‡Please note that there was a reduced total of atrial fibrillation events in the fourth and fifth serum magnesium quintiles among African Americans (52 and 26, respectively), and a modest interaction between serum Mg and race was identified (p=0.04).

Figure 3

Association between serum magnesium quintile and atrial fibrillation stratified by age, Atherosclerosis Risk in Communities, 1987 to 2009. *Cox proportional hazards model adjusted for age, sex, race, study site, body mass index, high density lipoprotein cholesterol, low density lipoprotein cholesterol, serum potassium, serum creatinine, smoking status, drinking status, educational level, systolic blood pressure, diabetes, antihypertensive medication, and prevalent myocardial infarction, heart failure, or stroke. †The reference group is the third serum magnesium quintile.