MONDAY, Nov. 10 (HealthDay News) -- Someone who has taken the clot-preventing drug Plavix less than five days before having bypass surgery runs a higher risk of excess bleeding, is more likely to require a second operation, and will spend more time in the hospital, says a study that buttresses current guidelines.

Those guidelines from the American College of Surgeons recommend discontinuing Plavix five to seven days before coronary artery bypass surgery, said Dr. Richard C. Becker, a professor of medicine in cardiology and hematology at Duke University, and co-author of a report in the Nov. 18 issue of the Journal of the American College of Cardiology.

"Those guidelines were based on data we thought could be strengthened specifically by defining what the risk of bleeding might be," Becker said. The guidelines say that bypass surgery can be done on people who have been taking Plavix, if the need for surgery is urgent, and the risk of extra bleeding is deemed acceptable.

So, Becker and his colleagues at Duke and other institutions studied 596 people who had bypass surgery at 14 hospitals for acute coronary syndromes such as heart attacks.

Major bleeding occurred in 35 percent of the 298 participants who had taken Plavix within five days of the surgery, compared to 26 percent of the 298 who had not taken the drug in that period, the researchers found.

Those who had taken Plavix were three times more likely to require a second procedure because of bleeding than those not taking the drug -- 6.4 percent versus 1.7 percent. And the average hospital stay was 9.7 days for those who took the clot-preventing medication versus 8.6 days for those who didn't.

"Those results are consistent with some prior observations," Becker said. "They added information about bleeding not only in terms of transfusions but also hospital stay and chest tube output."

Chest tube output is bleeding through the tube inserted for the bypass procedure.

The new study "is able to show that the five-day window is important," Becker said. "Every day you wait lessens the risk."

"The study has confirmed what we all suspected," said Dr. Jawahar L. Mehta, director of molecular cardiology and holder of the Stebbins Chair in Cardiology at the University of Arkansas for Medical Sciences. "I don't think there is anything in it that is upsetting. This was expected."

The risks of operating within the five-day period "have never been studied before in a systematic fashion," Mehta said.

Bypass surgery should not be performed until five days after Plavix is stopped, "unless there is an absolute emergency to operate, which is not often these days, because we have other approaches," Mehta said.

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