AKI After Angiography Raises Risks

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MONTREAL—Patients who experience acute kidney injury (AKI) after undergoing coronary angiography have more than double the long-term risk of dying and a 74% greater likelihood of being hospitalized for heart failure than those who do not develop AKI, a study found.

Lead investigator Matthew T. James, MD, presented study findings at the Canadian Society of Nephrology's 2010 annual meeting.

“This [study] shows that even if you're well enough to go home, there are still risks associated with AKI following angiography,” said Dr. James, Assistant Professor of Nephrology at the University of Calgary in Alberta, where is a clinical scholar completing his doctorate in community health sciences.

He and his co-investigators used the APPROACH database—which includes everyone who undergoes a coronary angiogram in Alberta—as well as the Northern Alberta and Southern Alberta Renal Program databases, which include everyone in the province receiving dialysis or a kidney transplant.

The team examined the outcomes of adult Albertans who had a coronary angiogram in 2004, 2005, or 2006. They excluded patients with pre-existing end-stage renal disease (ESRD) as well as those who did not have creatinine measurements before angiography or within seven days after the procedure, and those who died before hospital discharge. The investigators gathered outcomes information from several sources, including Alberta Vital Statistics and Alberta Health and Wellness. The researchers followed patients until March 31, 2007.

Out of 14,782 patients, 12,635 had a post-angiography change in serum creatinine of less than 25% (no AKI), 1,330 had a 25%-49% increase (mild AKI), and 572 had a 50% increase or greater (severe AKI).

The patients with severe AKI had more comorbidities, including a higher prevalence of proteinuria, diabetes, hypertension, heart failure, and other forms of cardiovascular disease. Furthermore, they had significantly higher rates of severe coronary vascular disease and low left ventricular ejection fraction as revealed by coronary angiography.

Subjects with mild and severe AKI had three- and four-fold increases in the long-term adjusted risk of ESRD, respectively. Additionally, the adjusted risk of mortality following discharge among those with mild AKI post-angiography was increased 1.6-fold compared with patients without AKI; the risk was more than twofold greater with severe AKI.

Similarly, the long-term adjusted risks of hospitalization for heart failure in these two groups were significantly elevated by 40% and 70%, respectively. The risk of hospitalization for a heart attack was significantly elevated in those with mild AKI, but not among those with severe AKI.

“There remains uncertainty with respect to the associations between AKI and risk of hospitalization for myocardial infarction in the study,” Dr. James told Renal & Urology News after his presentation. “We did not observe a similar dose-response relationship with severe AKI as we did for the risks of death, ESRD, and hospitalization for heart failure.”

Brendan Barrett, MD, Professor of Medicine at Memorial University of Newfoundland in St. John's, commented that it remains to be determined whether these relationships are causal.

“If in fact the acute change in kidney function is a cause of the later outcomes, then there is a great need for effective preventive therapies,” Dr. Barrett said. “However, if the acute kidney injury is not the cause, then prevention may have less clinical impact. The answer to this question is the subject of some trials that are in the design phase.”

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