Acute kidney injury resulting from exposure to contrast media increases likelihood of death
AN INCREASE in serum creatinine as small as 0.3 mg/dL resulting from acute kidney injury after exposure to a contrast agent greatly raises mortality risk, data suggest.
Traditionally, contrast nephropathy has been defined as an increase in serum creatinine of 0.5 mg/dL or more or 25% or greater. The long-term significance of acute kidney injury (more recently defined as a serum creatinine increase of 0.3 mg/dL or more or 25% or more due to contrast agent exposure) has not been well defined, however.
Researchers at the University of Arkansas in Little Rock reviewed data on long-term mortality for 676 patients who underwent cardiac catheterization from January 1, 2004 through December 31, 2004 at the Central Arkansas Veteran Affairs Health Care System in Little Rock. The mean follow-up was 19.2 months, with a total follow-up of 1,068 patient-years. Subjects were not on dialysis at the time of catheterization and they had at least one or more serum creatinine levels reported within 72 hours after the procedure. All the patients were given iodixanol as their contrast agent.
Acute kidney injury developed in 45 (6.7%) patients, increasing their mortality risk fivefold after adjusting for gender, race, CKD, diabetes mellitus, and hypertension, according to lead investigator Muhammad Alam, MD, assistant professor of medicine.
“We need to rethink how we view acute kidney injury. In some ways this is a wake-up call,” Dr. Alam said. “Most [clinicians] traditionally have felt that an increase of 0.3 or 0.5 mg/dL
in serum creatinine is usually reversible and the patients get back to normal. Now, we are reporting that this is probably not true.”
He added that the problem is not specifically related to the use of iodixanol. “This contrast medium is considered the safest media for cardiac catherization.”
It is theorized that contrast agents used for catherization cause a severe constriction of renal blood vessels, but no mechanisms of action for contrast-induced nephropathy have been proved and no modality has been shown to counteract these creatinine spikes. Nephrologists need to be aware that even a small increase in serum creatinine, even one that is normally thought of as reversible, may not be, Dr. Alam told Renal & Urology News. “These patients should be carefully followed and we should make sure that all the risk factors, including the cardiac risk factors, are aggressively managed in these patients,” he said.