Contrast-induced acute kidney injury in renal transplant recipients after cardiac catheterization

Renal transplant (RTX) recipients remain at high-risk for acute kidney injury (AKI) despite having improved renal function and quality of life after transplantation. We sought to identify the incidence and risk factors for contrast-induced AKI in RTX recipients after cardiac catheterization at our institute as identified by electronic records. After excluding patients on dialysis at time of procedure due to failed transplant and who did not have post-exposure creatinine values within 3 days, we reviewed 77 procedures on 57 patients. We studied one case per patient (the most recent procedure). Among the 57 patients, 42 were male, 42 were Caucasian and mean age was 58.2 ± 10.1 years. Mean serum creatinine 24 h pre-procedure was 1.7 ± 0.8 mg/dl. Contrast-induced AKI, defined as rise in serum creatinine of 25% or 0.5 mg/dl within 3 days post-catheterization, occurred in 9 procedures (15.8%). One procedure was complicated by AKI requiring dialysis. AKI occurred more frequently with use of low-osmolar contrast (ioxaglate or iohexol) in comparison with iso-osmolar contrast (iodixanol) (9/36 vs. 0/21, p = 0.019). Patients who received prophylactic N-acetylcysteine had lower incidence of AKI than those who did not (4/41 vs. 5/16, p = 0.046). Exact logistic regression analysis revealed odds ratio of developing AKI with use of low-osmolar vs. iso-osmolar contrast to be 7.747 (1.101 ― ∞); p = 0.0381). Contrast-induced AKI was common in RTX recipients after cardiac catheterization. Iso-osmolar contrast was associated with a lower risk of contrast-induced AKI in comparison with low-osmolar contrast.