Abstract 970: Plasma Magnesium as a Predictor of Sudden Cardiac Death: Findings From the Nurses’ Health Study
Background: Magnesium (Mg) has anti-arrhythmic properties in experimental and cellular models, and myocardial Mg levels have been found to be lower in victims of sudden cardiac death (SCD) as compared to victims of trauma in autopsy series. However, whether plasma Mg can predict risk of SCD is unknown.
Methods: We conducted a prospective, nested case-control analysis among 32,826 women in the Nurses’ Health Study, aged 44 – 69 at the time of blood draw. Over 16 years, 99 cases of sudden and/or arrhythmic cardiac death validated by review of medical records and/or next-of-kin reports were matched to 3 controls on age, ethnicity, smoking status, time/date of blood draw, fasting status and presence of CVD using risk set sampling. Conditional logistic regression models, adjusted for dietary, lifestyle and other CVD risk factors and biomarkers, estimated the relative risk (RR) and 95% confidence intervals (CIs).
Results: Plasma Mg was linearly inversely associated with risk of SCD (Table⇓). After adjustment for potential confounders, women in the highest quartile had a 77% (95%CI, 40%–91%) lower risk of SCD compared to women in the lowest quartile (P trend=0.003). When analyzed as a continuous variable, each 0.25 mg/dL (1 SD) increment in plasma Mg was associated with a 41% (95%CI, 15%–58%) lower risk of SCD, and women with plasma Mg above the pre-specified cut-point of 2.0 mg/dL were at an increased risk of SCD (RR, 0.48; 95%CI, 0.25– 0.95). This association was not appreciably altered in analyses limited to women without a history of prior cardiovascular disease.
Conclusions: Plasma Mg levels are strongly associated with lower risk of sudden death in women, independent of established risk factors for CHD and SCD. Plasma Mg is an easily measured biomarker that may serve as a simple clinical screening tool to identify women at high risk for developing fatal arrhythmias and SCD.