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The Drug of Choice in a Heart-Stopping Emergency

Study finds amiodarone twice as effective as lidocaine

WEDNESDAY, March 20, 2002 (HealthDayNews) -- The patient is rushed into the emergency room close to death, with a heart that has stopped pumping blood because its regular beat has been changed to the irregular fluttering called ventricular fibrillation.

The emergency room tries to restore a regular beat by using a defibrillator to give an electric shock. It doesn't work. A second and a third shock also fail.

What then?

Current American Heart Association guidelines say the doctor should inject a drug that can restore normal heart rhythm. A relatively new drug, amiodarone, is preferable, the guidelines say, but an older drug, lidocaine, can also be used. Lidocaine, in fact, is used by many emergency rooms, mostly out of force of habit.

But in what one expert calls a "landmark finding," a carefully controlled new trial has tipped the scales firmly in favor of amiodarone, at least in terms of immediate survival.

Amiodarone was almost twice as effective as lidocaine at keeping patients alive so they could be admitted to the hospital, says a report in tomorrow's New England Journal of Medicine by emergency care physicians at St. Michael's Hospital in Toronto.

"Like a lot of things in medicine, which medication to use hasn't been based on science, it's been based on what has always been done," says Dr. Dan Cass, chief of emergency medicine at St. Michael's, and a leader of the study. "This is the first trial that looked at a new therapy compared to an old therapy."

The results were striking. Of the 180 patients given amiodarone, 22.8 percent survived to be admitted to the hospital. The survival rate for the 167 patients who were given lidocaine was 12 percent.

It is "a landmark study, an important study that starts to lead us to ultimate answers," says Dr. Vinay Nadkarni, professor of anesthesia and pediatrics at the University of Pennsylvania, and chairman of the American Heart Association's emergency cardiovascular committee, which helps set the drug-use guidelines.

But the Canadian study does not provide the ultimate answer, Nadkarni adds. "The main question that remains unanswered is whether a medicine or other intervention improves survival to hospital discharge," he says.

"What is needed now is a large, multicenter trial looking at the effects of therapy not only on survival to hospital admission but to hospital discharge," Cass adds.

Although such a study is "desperately needed," it would be difficult to plan and carry out, Nadkarni says, in part because of the ethical issue of withholding a drug from patients that has been shown to be effective in the short term.

The immediate effect of the Canadian study will be to "very much support and corroborate the guidelines that were set in August 2000," Nadkarni says. "This study is very much in step with those guidelines," which call amiodarone the drug of choice.

Choosing his words carefully, Nadkarni says the Canadian study, "under certain conditions, which are dependent on the emergency medical system, will potentially change practice for those systems that believe improved survival to hospital admission is a clinically important outcome."

What To Do

Whatever the emergency room treatment, its effectiveness depends on the speed with which it is given. So people should be aware of the signs and symptoms of a heart attack or ventricular fibrillation and the need to get help quickly.

For a primer on ventricular fibrillation, go to the American Heart Association, or this U.S. Food and Drug Administration site.

SOURCES: Dan Cass, M.D., chief of emergency medicine, St. Michael's Hospital, Toronto, Canada; Vinay Nadkarni, M.D., professor of anesthesia and pediatrics, University of Pennsylvania, Philadelphia; March 21, 2002, New England Journal of Medicine
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