Atrial fibrillation risk higher in those with low serum magnesium

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By David Liu, PHD

Tuesday Nov 27, 2012 (foodconsumer.org) -- Magnesium insufficiency or deficiency may increase risk of atrial fibrillation (AF) in individuals without heart disease, according to a study in Circulation.

Low serum magnesium has been associated with increased risk of atrial fibrillation in patients who have received cardiac surgery, according to the background information in the study report.

A. May Khan at University of Pennsylvania in Philadelphia, PA and colleagues conducted the study and found 
those with lowest serum magnesium were almost 50% more likely than those with the highest serum magnesium to develop atrial fibrillation.  The risk estimation was adjusted for conventional atrial fibrillation risk factors, use of antihypertensive drugs, and serum potassium levels.

The association was derived from a data set from 3,530 participants  at a mean age of 44 years who were free of atrial fibrillation at baseline when enrolled in the Framingham Offspring Study.  All participants were followed for up to 20 years during which 228 men and women developed atrial fibrillation.

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. 

The age- and sex-adjusted incidence rate of atrial fibrillation was 9.4 per 1,000 person-years among those in the lowest quartile of serum magnesium (lower than 1.77 mg/dl), compared to 6.3 per 1000 person-years among those in the highest quartile of serum magnesium (higher than 1.99 mg/dl).

The researchers concluded "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."

Another study in Circulation Journal also found that low serum magnesium was associated with elevated risk of atrial fibrillation in both whites and African Americans.

J. R. Misialek at School of Public Health, University of Minnesota and colleagues studied data from14,290 men and women at a mean age of 54 years who were free of atrial fibrillation at baseline when enrolled in the Atherosclerosis Risk in Communities study in the U.S. and found those in the lowest quintile of serum magnesium were 34% increased risk of atrial fibrillation, compared with those in the highest quintile.

Atrial fibrillation is the most common cardiac arrhythmia or simply irregular heart beat.  It does not often produce any symptoms, but is often associated with palpitations, fainting, chest pain, or congestive heart failure. 

Atrial fibrillation is known to increase risk of stroke; people with this condition can have risk of stroke 7-fold higher than those in the general population.

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