Four years after Bayer agreed to suspend sales of its Trasylol drug, which is used to control bleeding during heart surgery, Health Canada is allowing the drugmaker to resume sales after conducting a safety review that the agency says shows the benefits outweigh the risks.

The decision is a remarkable turnaround for a drug that was withdrawn four years ago from many markets, including the US, after study called BART was halted early because patients given Trasylol had a more than 50 percent higher death rate than patients who got other, cheaper drugs. The results were later published in The New England Journal of Medicine and an accompanying editorial proclaimed that “in all likelihood, this is the end of the aprotinin story.” Aprotinin is the chemical name.

Trasylol was widely used to prevent life-threatening blood loss during coronary bypass graft surgery, or CABG. Patients undergo CABG surgery to improve blood flow to the heart when they are at a high risk of heart attack and even death due to blocked arteries. But the drug was also used in higher risk surgery to prevent a dangerous loss of blood, and the trial found a higher death risk in these patients.

At the time of the 2007 withdrawal, Trayslol was already mired in controversy, including an alleged Bayer cover-up of side effects prior to an FDA panel meeting (see this). A doctor charged that 22,000 lives could have been saved if the FDA removed Bayer’s Trasylol two years earlier, when his study revealed a growing number of deaths linked to the drug, which was widely used for heart bypass surgery (read here).

To prevent further patient harm, Health Canada has asked Bayer to add a boxed warning on the labeling and the drugmaker will have to conduct further studies to assess safety and efficacy in higher risk patients undergoing more complex cardiac surgeries. “Canadians can be confident that should new safety information emerge, Health Canada will take appropriate action and keep health professionals and Canadians informed,” the agency says in a statement.

However, one of the BART trial investigators is not pleased. “What we did and what we found - not changed,” Paul Hebert tells The Winnipeg Free Press. “The truth is it’s a very expensive drug that was being used with the thought that it prevented massive bleeding. We said ‘You know, what? Yes, it prevents a little bit of massive bleeding, but it causes an excess mortality of two per cent.’ So in the population we studied, there was no evidence of benefit.”