Aims: Cardiac surgery and coronary angiography are both associated with risk of acute kidney injury (AKI). We hypothesized that the risk of post-operative AKI increases when coronary angiogram and cardiac surgery are performed in close succession, without sufficient time for recovery from the adverse effects of intravenous contrast.
Methods and results: We included 2133 consecutive patients who underwent cardiac surgery at the Minneapolis Veterans Administration Medical Center from 2004 to 2010. Acute kidney injury was defined by the AKI network and the risk, injury, failure, loss, end-stage (RIFLE) criteria. Patients were 66 ± 10 years old. Mean pre-operative creatinine and estimated glomerular filtration rate were 1.1 ± 0.4 mg/dL and 75 ± 22 mL/min/1.73 m(2), respectively. Cardiac surgery was performed 14 days (range 0-235) after coronary angiography. Acute kidney injury occurred in 680 (32%) patients per AKI network, 390 (18%) patients per RIFLE risk, and 111 (5%) patients per RIFLE injury criteria. Age, body mass index, diabetes mellitus, New York Heart Association class III/IV, cardiopulmonary bypass time, and impaired pre-operative renal function were independent predictors of AKI. However, time between coronary angiogram and cardiac surgery was not a predictor (P = 0.41). AKI occurred in 35% of 433 patients operated within 3 days of coronary angiogram vs. 31% of 1700 patients operated after 3 days (P = 0.17). Results were the same in patients with impaired pre-operative renal function and those with contrast-induced nephropathy.
Conclusion: Risk of AKI after cardiac surgery is not influenced by the time between coronary angiogram and cardiac surgery. These results do not support the notion of delaying cardiac surgery for the sole purpose of renal recovery after coronary angiogram.