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Heart Rhythm Drug Does the Trick

Reduced abnormal heartbeats by 50% in most heart patients, study finds

TUESDAY, Dec. 27, 2005 (HealthDay News) -- A carefully controlled study proves the value of amiodarone, a drug that prevents abnormal heart rhythms, for people who have heart surgery, Canadian researchers report.

Overall, giving amiodarone for 13 days, starting six days before the operation, halved the incidence of abnormal heartbeats such as atrial fibrillation, the researchers reported.

From 30 percent to 50 percent of people who have valve replacement or bypass operations can have such abnormal heartbeats, which lengthen hospital stays and can be life-threatening. Some doctors have hesitated to use the powerful drug, said study author Dr. L. Brent Mitchell, "primarily because of conflicting evidence from previous studies." The drug's benefits are balanced by its potential toxicity; lung disease is one of its most noted side effects.

The new study, reported in the Dec. 28 issue of the Journal of the American Medical Association, shows that "it works in everybody," said Mitchell, from the University of Calgary.

The study was done "to consolidate the information about the effect of the drug, with the hope that its use becomes more widespread," added Mitchell, who is director of the university's Lidin Cardiovascular Institute of Alberta.

There were 601 patients in the study, which made it "at least twice as big as any previous trial," Mitchell said. Half of them got the 13-day course of amiodarone, while the others got a placebo.

Most important, the people chosen for the study were carefully selected to cover the full range of heart surgery patients, he said, "young, old, valve surgery, people protected by beta blockers," a different class of drugs often used for such patients.

"There was a substantial protective effect in all six groups," Mitchell said. "It works whether a person gets a beta blocker or not."

The protective effect is especially important in high-risk patients, such as older people and those having valve surgery, he said. "The higher the risk a patient population has, the more important the 50 percent reduction becomes," Mitchell said.

The study does go "a long way to support the use of amiodarone," said Dr. Joseph P. Mathew, an associate professor of anesthesiology at Duke University Medical Center, and co-author of an accompanying editorial.

But he stopped short of endorsing the use of the drug for all heart surgery patients.

Mathew's hesitance was based on what he called "a couple of limitations" of the trial. The most significant, he said, was a lack of data about how many patients were started on beta blockers and then had that medication stopped.

"Withdrawal from beta blockers occurs because cardiac function is not as good as it should be," Mathew said. "When patients are withdrawn from beta blockers, the risk is doubled. There is no information about what percentage of patients was actually withdrawn from beta blockers."

And while there was no increased incidence of complications in the patients getting amiodarone, there also was no difference in readmissions to the hospital, in-hospital deaths or deaths in the year after surgery.

The cautious recommendation of the editorial was that "more widespread use of amiodarone for patients undergoing elective cardiac surgery should be considered."

More information

A complete rundown on amiodarone is offered by the National Library of Medicine.

SOURCES: L. Brent Mitchell, M.D., director, Lidin Cardiovascular Institute of Alberta, Calgary; Joseph P. Mathew, M.D., associate professor, anesthesiology, Duke University Medical Center, Durham, N.C.; Dec. 28, 2005, Journal of the American Medical Association
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