The effect of timing of cardiac catheterization on acute kidney injury after cardiac surgery is influenced by the type of operation

BACKGROUND: Acute kidney injury (AKI) is a vexing complication of cardiac surgery. Since exposure to contrast agents is a relevant contributing factor in the development of postoperative AKI, the optimal timing between cardiac catheterization and surgery is decisive.

METHODS: A total of 2504 consecutive nonemergent patients undergoing isolated coronary artery bypass grafting (CABG), valve surgery (with or without concomitant CABG), and proximal aortic procedures were enrolled. AKI was defined by consensus RIFLE (Risk, Injury, Failure, Loss of function, End-stage renal disease) criteria. The association of postoperative AKI and time between cardiac catheterization and operation was evaluated using multivariable logistic regression modeling and propensity-matched analysis.

RESULTS: Postoperative AKI occurred in 230 (9%) patients. The median number of days from cardiac catheterization to operation was 5 (25th to 75th percentile: 2 to 10). The incidence of AKI was significantly higher in patients operated on ≤1 day after cardiac catheterization compared to those operated on >1 day after (13% vs. 8%, p=0.004). The time interval between cardiac catheterization and surgery (tested both as a continuous and a categorical variable) was not an independent AKI predictor in the propensity-matched population or the pre-matched one. Contrast exposure≤1 day before surgery was independently associated with postoperative AKI in patients undergoing valve surgery with concomitant CABG only (post-matched: OR 3.68, 95%CI 1.30 to 10.39, p=0.014).

CONCLUSIONS: Delaying cardiac surgery beyond 24h of exposure to contrast agents seems to be justified only in patients undergoing valve surgery with concomitant CABG.