Magnesium No Way to Treat a Heart Attack
Newer drugs and treatments far more effective
THURSDAY, Oct. 17, 2002 (HealthDayNews) -- Doctors hoped it would be an easy and inexpensive way of improving the odds of surviving a heart attack.
But a new study shows that magnesium given intravenously to people hospitalized for heart attacks does nothing.
The study appears in this week's issue of The Lancet.
"In viewing the totality of available evidence in current coronary care practice, there is no indication for the routine administration of intravenous magnesium to patients," says Dr. Elliott Antman, the lead author of the study and the director of the coronary care unit at Brigham and Women's Hospital in Boston.
Researchers gave 3,113 heart attack patients magnesium sulfate intravenously for the first 24 hours after they were hospitalized. Another 3,100 patients received a placebo.
Researchers found no difference in the death rate over the next 30 days.
The finding shows just how far treating heart attacks patients has come, doctors believe.
Magnesium was commonly given to heart attack victims in the 1970s and '80s. The reason: A primary cause of death from heart attacks is the dangerous arrhythmias that force the heart to beat wildly before finally giving out. Magnesium is known to calm the heart muscle, Antman says.
Studies back then showed that magnesium reduced short-term mortality by as much as 50 percent.
But studies in the 1990s showed magnesium had little effect.
"Since magnesium is such a cheap treatment, we felt it was important to evaluate this highly cost-effective and potentially life-saving treatment," Antman says.
In the '90s, more effective heart attack medications became available, he adds.
When treating a heart attack, doctors can attempt to minimize the damage in two ways, explains Dr. Chris White, chairman of the department of cardiology at Ochsner Clinic Foundation in New Orleans.
The first is by calming the heart, making it work less so it requires less oxygen. That's how doctors treated heart attacks prior to the '90s, with treatments like magnesium, White says.
The second method -- one that has been the focus of much research for the last 15 years -- is increasing the amount of oxygen to heart tissue.
One way is the use of "thrombolytic" -- or "clot-busting" -- drugs that limit damage to the heart muscle by dissolving clots that block arteries.
Then there's angioplasty, in which a catheter is threaded through an artery to improve blood flow in a narrowed vessel. At the tip of the catheter is a tiny balloon that's inflated to stretch the vessel.
It's also now know that aspirin, which interferes with blood clotting, can help keep arteries open in people who've had a heart attack. And ACE inhibitors block an enzyme in the body that is necessary to produce a substance that causes blood vessels to tighten.
These treatments weren't widely available until the '90s, Antman says.
"It's possible the beneficial effect of magnesium is superceded by the effects of current medical regimen," Antman says.
Magnesium is no longer routinely given to patients, White says. "The real hope was that . . . it would work synergistically with the clot-busters. Unfortunately, that didn't happen."
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