Acute kidney injury after cardiac surgery: does the time interval from contrast administration to surgery matter?

Objective The authors sought to evaluate the association between the time interval from contrast administration to cardiac surgery and postoperative acute kidney injury (AKI). Design A retrospective observational study over a 1-year period. Setting A US academic medical institution. Participants Six hundred forty-four adult patients undergoing nonemergent cardiac surgery. Interventions No interventions were performed as part of the study. Measurements and Main Results AKI was defined as an increase in serum creatinine by ≥0.3 mg/dL or ≥50% above baseline within the first 2 postoperative days or the commencement of renal replacement therapy within the same period. Using a contrast-to-surgery time interval >7 days as the baseline, multivariable logistic regression analysis determined the association between a contrast-to-surgery time interval ≤1 day or 2 to 7 days and postoperative AKI adjusting for potential confounding variables. The incidence of AKI within the study cohort was 21.9%. After adjusting for other covariates, there was no association between the contrast-to-surgery time and AKI (odds ratio [OR] ≤1 day = 0.93; 95% confidence interval [CI], 0.52-1.66; p = 0.81; OR = 2-7 days = 1.28; 95% CI, 0.78-2.11; p = 0.34). Conclusions In an appropriately selected population, cardiac surgery can be performed within 1 day of cardiovascular catheterization and contrast administration without an increase in the incidence of postoperative AKI. Recommendations to delay cardiac surgery for a specified period after contrast administration to reduce the risk of postoperative AKI are premature. Additional evidence is required before making recommendations on optimal surgical timing after contrast exposure.