While age, history of kidney disease and an earlier heart attack were also associated with the risk of death, enzyme levels were still the strongest predictor.
According to the authors, the findings need confirmation in large clinical trials, but levels of these enzymes might one day be used as markers for bypass surgery outcomes. Doctors often test for elevated creatine kinase or troponin levels to confirm a heart attack, but testing is not routinely done after bypass since these patients usually get aggressive treatment with statins and other medications.
Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles, said the findings could influence patient treatment.
"It is well-established that large increases in cardiac enzymes are associated with higher risk of subsequent mortality," Fonarow said. "However, the data as to whether smaller increases in cardiac enzymes are associated with increased risk have been mixed."
This new analysis suggests that elevations of these enzymes in the first 24 hours after coronary artery bypass grafting (CABG) surgery were associated with increased 30-day and one-year mortality even in patients with modest elevations, compared with patients who had no increase in enzyme levels, he said.
"Patients undergoing CABG who are found to have early elevations in cardiac enzymes should be recognized as being at higher risk for mortality and potentially treated more aggressively with cardiovascular protective medications," Fonarow said.
For more information on coronary artery bypass surgery, visit the American Heart Association.
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