Study says $2 dose lessens problems of heart surgery

November 04, 1992|By Jonathan Bor | Jonathan Bor,Staff Writer

In an era of skyrocketing drug costs, researchers have shown that a $2 infusion with one of the earth's most common elements greatly reduces the complications of open heart surgery.

When given in the closing minutes of heart surgery, magnesium cut in half the frequency of abnormal heart rhythms, lessened the need for drugs to combat arythmias and shortened the time patients spent on respirators.

Dr. Bart Chernow, the chief physician at Baltimore's Sinai Hospital, said yesterday he was so delighted with the findings that he believes one-time magnesium infusions should be given to all patients undergoing heart bypass and valve replacement surgery.

But, despite several years of studying the mineral, he admits he doesn't know why it works so well.

"I don't know, and I don't think anyone understands the mechanism of this. Now, we've tested the hypothesis that giving it is good. But I can't tell you why it is. Magnesium, as simple an element as it is, has really kept us in the dark."

Dr. Chernow began the study of 100 patients while working at the Massachusetts General Hospital in Boston; all the patients spent time in the intensive care unit there. He later analyzed the results after becoming chief physician at Sinai Hospital two years ago.

The study is described in today's Journal of the American Medical Association.

A specialist in critical-care medicine, Dr. Chernow noticed several years ago that 60 percent of intensive care patients had low magnesium levels, including those who had undergone open heart operations. This caused him to wonder whether a replacement dose of magnesium following surgery would reduce the complication rate.

In his study, eight of 50 patients receiving a dose of magnesium developed abnormal heart rhythms. In contrast, 17 of 50 patients receiving a placebo had the problem.

Erratic heartbeat is the most frequent complication of open heart surgery and the one most responsible for post-surgical deaths. Less than two patients out of every 200 die in the days and weeks following surgery.

It's a small mortality rate, he said, but one that could probably be lowered if patients received preventive doses of magnesium.

In the study, the patients given magnesium spent less time on respirators. Eight of 50 patients receiving magnesium stayed on the breathing machines for more than a day, compared with 15 of 50 patients receiving the placebo.

Even after surgery, patients have to be kept on respirators for some length of time because the lingering effects of anesthesia include a depressed breathing rate. "But the magnesium seems to wake their respiratory systems sooner," Dr. Chernow said.

Dr. Chernow said doctors will have to decide for themselves whether to give magnesium routinely to patients completing heart operations. But at Sinai, doctors began administering the drug as a matter of routine more than a year ago.

"We just think it's worthwhile giving it to everybody undergoing open heart surgery," Dr. Chernow said. "It's cheap, it's a generic drug made by about 10 companies, and it has no side effects."

Some 300,000 people have open heart operations each year.

There is no reason for healthy people to take magnesium as a dietary supplement, he said. While most people would flush it harmlessly out of their bodies, people with kidney problems would have trouble excreting it.

The main point, he said, is that a healthy diet provides enough magnesium for just about everybody.

In another study, doctors are testing the theory that magnesium helps people recover from heart attacks.

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