Introduction: Low serum magnesium (Mg) levels have been associated with increased coronary heart disease (CHD) risk, likely acting through pathways such as hypertension, hyperglycemia or inflammation. An early (1998) ARIC paper evaluated this association, based on 319 events, and identified a sex-interaction whereby the inverse Mg-CHD association was stronger among women than men. Nearly 2,000 events have occurred since the prior publication. Hence, we sought to update the analysis.
Hypothesis: We hypothesized serum Mg would be inversely and independently associated with long-term risk of CHD.
Methods: A total of 14,465 ARIC study participants without CHD at visit 1 (baseline) were included. Serum Mg was measured at visit 1 (1987-89) and visit 2 (1990-92). Incident CHD events were identified through 2014 using annual telephone calls, hospital discharge lists and death certificates, and were adjudicated by physician review. Multivariable Cox proportional hazards regression models were used. Serum Mg was categorized into quintiles based on mean visit 1 and 2 concentrations. Based on prior findings in ARIC suggesting an interaction, we decided a priori to provide sex-stratified results.
Results: Participants at baseline were mean±SD age 54±6y, 57% were women and 27% black. Serum Mg was 1.62±0.14 mEq/L overall, 1.62±0.14 mEq/L among women and 1.63±0.14 mEq/L among men. Over a median follow-up of 25 years, 1,939 CHD cases were identified. Overall, serum Mg was inversely and monotonically associated with CHD risk after adjustment for demographics, lifestyle factors and other CHD risk factors (Table, p-trend<0.001). The association was stronger among women (HR Q5 vs Q1=0.63) than men (HR=0.83), but the sex-interaction was not statistically significant (p>0.05).
Conclusions: In this large community-based cohort, serum Mg was inversely associated with CHD risk. This association was slightly stronger among women than men. Further research is needed to understand if increasing Mg levels is a useful target for CHD prevention.