For patients with heart attack, high levels of rerouting are tied to a three percent higher risk of death, they report in the Journal of the American Medical Association. “For every hundred patients there are three avoidable deaths,” said Dr. Renee Hsia, an emergency physician at the University of California, San Francisco, who led the study. “Now we actually have empirical evidence to show crowding affects patients in a very real way,” she told Reuters Health. The new study is the largest so far to size up the health toll of ambulance diversion, a common way of taking pressure off the nation’s overflowing ERs, which experts say are reaching a breaking point. Just last month, Hsia and colleagues found that the number of ERs in the U.S. has dropped by more than a quarter over the past two decades. At the same time, patient visits have shot up by 35 percent.