Low serum magnesium is moderately associated with the development of AF in individuals without cardiovascular disease.
Circulation: November 12, 2012
Background—Low serum magnesium has been linked to increased risk of atrial fibrillation (AF) following cardiac surgery. It is unknown whether hypomagnesemia predisposes to AF in the community.
Methods and Results
We studied 3,530 participants (mean age, 44 years; 52% women) from the Framingham Offspring Study who attended a routine examination, and were free of AF and cardiovascular disease. We used Cox proportional hazard regression analysis to examine the association between serum magnesium at baseline and risk of incident AF. Analyses were adjusted for conventional AF risk factors, use of antihypertensive medications, and serum potassium. During up to 20 years of follow-up, 228 participants developed AF. Mean serum magnesium was 1.88 mg/dl. The age- and sex-adjusted incidence rate of AF was 9.4 per 1,000 person-years (95% confidence interval, 6.7 to 11.9) in the lowest quartile of serum magnesium (≤1.77 mg/dl), compared with 6.3 per 1,000 person-years (95% confidence interval, 4.1 to 8.4) in the highest quartile (≥1.99 mg/dl). In multivariable-adjusted models, individuals in the lowest quartile of serum magnesium were approximately 50% more likely to develop AF (adjusted hazard ratio, 1.52, 1.00 to 2.31; P=0.05), compared with those in the upper quartiles. Results were similar after excluding individuals on diuretics.
—Low serum magnesium is moderately associated with the development of AF in individuals without cardiovascular disease. Because hypomagnesemia is common in the general population, a link with AF may have potential clinical implications. Further studies are warranted to confirm our findings and elucidate the underlying mechanisms.
Image: Crystallized Magnessium
Mild hypomagnesemia is a common electrolyte abnormality , particularly in the elderly who may have increased urinary magnesium losses due to diuretic therapy or interstitial renal disease. Whether this abnormality should be treated or prevented with prophylactic magnesium administration is unclear. The major concern is whether mild magnesium depletion predisposes to cardiac arrhythmias. There are conflicting data as to whether this occurs in otherwise healthy subjects. A report on over 3000 patients from the Framingham Heart Study suggests that how arrhythmia is defined is an important determinant . No association with hypomagnesemia was noted for more than 10 ventricular premature complexes (VPCs) per hour or for repetitive VPCs. There was, however, an increased risk of complex or frequent (≥30/hour) VPCs with reductions in the plasma magnesium concentration of 0.16 meq/L (0.2 mg/dL or 0.08 mmol/L) or more. The formulas to convert between these units can be found elsewhere.
Low serum magnesium is associated with an increased risk of CHD mortality and SCD. Although low magnesium
was associated with both carotid intima-media thickness and heart rate, this did not explain the relationship between serum
magnesium and CHD mortality or SCD. Future studies should focus on why magnesium associates with CHD mortality and SCD
and whether intervention reduces these risks