Magnesium Depletion, Metabolic Impairment, and Cardiac Alterations: The NAKO-MRI Study With Mendelian Randomization.

CONTEXT: Magnesium deficiency may contribute to subclinical cardiac changes, particularly metabolic diastolic cardiomyopathy.

OBJECTIVE

To investigate the association between magnesium depletion, metabolic syndrome (MetS), and magnetic resonance imaging (MRI)-derived cardiac alterations in a population-based sample.

METHODS

We cross-sectionally analyzed participants (N = 9568) from the baseline examination of the German National Cohort who underwent whole-body MRI. Associations of serum magnesium and magnesium depletion score (MDS) with MetS and cardiac alterations were assessed using multivariable logistic and linear regression, respectively. Two-sample Mendelian Randomization was performed to evaluate the potential causal relationship between serum magnesium and MRI-derived cardiac parameters.

RESULTS

Our analysis revealed no correlation between serum magnesium and MDS (Spearman's rho = 0.065; P < .001). A 1-SD increase in serum magnesium was associated with lower MetS prevalence (odds ratio, 0.93 [95% CI, 0.88-0.99]) and reduced left and right ventricular systolic and diastolic volumes. Higher MDS, indicating magnesium deficiency, was linked to increased MetS prevalence (OR per 1 unit, 1.32 [95% CI, 1.23-1.41]) and its individual components. Furthermore, higher MDS was associated with increased left ventricular remodeling index (estimate, 0.012 g/mL [95% CI, 0.008-0.017]) and decreased left ventricular end-diastolic volume (estimate, -1.132 mL/m2 [95% CI, -1.538 to -0.727]), indicating concentric hypertrophy. Two-sample Mendelian Randomization suggested no causal relationship between serum magnesium and MRI-derived cardiac markers.

CONCLUSION

Magnesium depletion may serve as an early indicator of cardiac impairment. However, Mendelian Randomization results do not support a causal role of serum magnesium on cardiac structure and morphology.