One reason for the conflicting results is that Hartford Hospital limited the use of aprotinin to patients undergoing particularly complex operations (and to patients like Jehovah's Witnesses, who refuse blood transfusions).

Another reason was that the Hartford Hospital doctors avoided a specific lab/drug test interaction that can lead to inadequate anti-clotting treatment. "During bypass or heart valve surgery, patients receive a drug called heparin to prevent blood clot formation," Dr. White explained. "Surgery teams know how much to give because they measure the activated clotting time (ACT). Previous studies have found that aprotinin makes the ACT rise erroneously if celite-ACTs are used. If you are using celite-ACTs to guide heparin dosing in a patient treated with aprotinin, you will think you gave enough heparin when in fact you didn't." This interaction may explain some of the increased risks with aprotinin reported in previous studies.

However, Dr White did not want to dismiss the importance of the previous studies showing harm. "Those studies were important, because they clearly showed that the way aprotinin was used around the world, by and large, was hurting patients more than helping them," said Dr. White. "By using aprotinin selectively and avoiding the celite-ACT test, surgical teams can reduce the risk of bleeding problems during surgery without increasing the risks of heart attack or stroke."

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Contact: Jayne Dawkins
ja.dawkins@elsevier.com
215-239-3674
Elsevier
29-May-2007