Dear Dr. Roach: Several months ago, I developed a case of a bigeminy heartbeat. My cardiologist prescribed metoprolol. At about the same time, I had reduced my intake of magnesium from about 50% of the daily value (DV) to 35%. (This may have preceded the bigeminy onset.)

Quite by accident, I read an article recommending magnesium for a heart arrhythmia. Within a week or so of reading the article, I started magnesium gluconate at 100% of the DV. I have been taking this and metoprolol for about a month, and my condition has improved about 95%.

The question is: How can we tell if the magnesium shorting down to 35% was actually the cause and increasing it to 100% was the cure? — L.R.

Answer: Bigeminy, more precisely ventricular bigeminy, is a term most people probably haven’t heard of, but most people have heard of a premature ventricular contraction (PVC). Ventricular bigeminy is when every other beat is a PVC and alternates with regular beats.

While this rhythm can happen in people without any heart disease or risk factors, your cardiologist will have considered many underlying causes, such as excess alcohol use, anemia, low oxygen levels, and thyroid disease. A beta blocker like metoprolol is usually the first drug that is used as beta blockers reduce adrenalin levels, reduce the oxygen needs of the heart, and are proven to be effective at reducing the number of PVCs.

A low magnesium level is another risk factor for PVCs and ventricular bigeminy, and there are case reports of the rhythm going away completely with magnesium. So, while we can’t be sure whether your bigeminy was caused by a low magnesium level, the story is suggestive that it’s a real possibility.

I don’t recommend taking magnesium except in people who have low levels, but 100% of the DV of magnesium is quite safe to take.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.