Only about 18 percent of such patients live long enough to leave the hospital, researchers found. Blacks fared worse than whites - a disparity only partly explained by more of them being treated in hospitals that did a poorer job of CPR.
Results were published in Thursday's New England Journal of Medicine.
Dr. Lance Becker, a University of Pennsylvania emergency medicine specialist and an American Heart Association spokesman, called the findings "grim" and "a wake-up call that we need to redouble our efforts" to find better ways to treat cardiac arrest.
It occurs when the heart quivers or stops beating entirely, because of a heart attack, a sudden heart rhythm problem, a drug overdose or other cause.
CPR, rhythmic chest compressions, can help maintain blood pressure and flow until more advanced treatments can be tried. Those might involve using a defibrillator to shock the heart back into a normal rhythm. Big strides have been made getting bystanders to do cardiopulmonary resuscitation and to use defibrillators, but the new study suggests that less improvement is occurring in the nation's hospitals.
Researchers led by Dr. William Ehlenbach at the University of Washington in Seattle analyzed the care of 433,985 Medicare patients treated from 1992 through 2005 around the United States.
Survival odds did not substantially change over time, they found. Blacks had survival rates about one-quarter lower than whites. Men, older patients, and people admitted from nursing homes also had lower survival rates after CPR. The study was funded by grants from the federal government and several foundations.
"It's troubling. We have made a lot of progress in out-of-hospital cardiac arrest," including a near tripling of survival rates in the Seattle area after community and rescue worker training efforts, said Dr. Paul S. Chan. He is a quality-of-care researcher at St. Luke's Mid America Heart Institute in Kansas City, Mo.
His own research, published in the New England journal last year, found that one-third of hospitalized patients do not get a potentially live-saving defibrillator shock within the recommended two minutes of suffering cardiac arrest.
Even when CPR is given by these highly trained hospital staffers, chest compressions often are too slow or too shallow to be effective, Chan said.
Guidelines recommend 100 chest compressions per minute, Chan said.
"Our performance in treating people with cardiac arrest is not improving," said Yale University cardiologist Dr. Harlan Krumholz. "Given that we know that there are delays to treatment across the country and those delays increase risk, there likely exists a big opportunity for hospitals to do better."
Dr. Gerald Buckberg, a surgeon at the UCLA Medical Center in Los Angeles, is trying radical approaches to improve survival, including use of a heart-lung machine to buy time while doctors try to fix the underlying problem that caused the cardiac arrest, such as clogged arteries triggering a heart attack.
By doing CPR independent of other steps to fix the underlying problem, "we have only treated the symptom of sudden death - we haven't treated the reason," Buckberg said.
Doctors have become too accepting of the fact CPR saves some patients, he said. "We should not accept the failure" that the vast majority die.