Does Contrast Exposure Cause Contrast-Induced AKI?

Contrast media exposure is not a “primary pathogenetic factor” in the development of acute kidney injury (AKI) after primary angioplasty, reports a study in the open-access Journal of the American Heart Association.

The researchers analyzed 2025 patients with ST segment-elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention at an Israeli hospital between 2000 and 2015. Median contrast dose was 150 mL. Rates of AKI were compared with those of 1025 patients undergoing fibrinolysis or no reperfusion therapy, who were not exposed to contrast medium. Acute kidney injury was defined as a creatinine level of 0.5 mg/dL or a creatinine increase of greater than 25% within 72 hours.

Overall AKI rates were similar between groups: 10.3% in patients undergoing primary angioplasty and 12.1% in the comparison group. A propensity score-matched analysis including 931 pairs also found no significant difference: 8.6% and 10.9%, respectively.

A wide range of factors were independently associated with AKI after primary angioplasty: age 70 or older, treatment with insulin or diuretics, anterior infarction, baseline estimated glomerular filtration rate, and variables reflecting pump failure and reduced left ventricular ejection fraction. The dose of contrast agent was not a significant factor. A risk score developed from the primary angioplasty group had similar discriminatory performance for AKI in the angioplasty and comparison groups.

Acute kidney injury occurring after primary percutaneous coronary intervention is commonly reported as “contrast-induced” AKI. However, other factors may contribute to this risk; previous studies of this issue have lacked a control group of patients not exposed to contrast medium.

The new analysis suggests that contrast exposure is not the primary cause of AKI after primary angioplasty in patients with STEMI. The increase in adverse outcomes with AKI after angioplasty appears to be independent of contrast exposure. The authors conclude, “[A]ttempts to reduce AKI rates in STEMI patients likely require targeting mechanisms that are unrelated to contrast media” [Caspi O, et al. Acute kidney injury after primary angioplasty: is contrast-induced nephropathy the culprit? J Am Heart Assoc 2017; doi.org/10.1161/JAHA.117.005715].

August 2017 (Vol. 9, Number 8)