Examining New Diagnostic Tests for Acute Kidney Injury After Heart Surgery

AKI, which is indicated by a sudden change in serum creatinine levels, is a serious complication that can occur after a patient undergoes CABG or heart valve surgery. People who experience AKI after heart surgery may be at increased risk for post-operative complications, including long-term kidney failure or heart damage. AKI is currently identified by testing serum creatinine levels in the blood, which is the traditional marker of kidney function. However, serum creatinine levels can be affected by other non-kidney-related factors and may not positively identify AKI until 48 hours after it begins. This study will examine three new biomarkers found in urine and blood-urine interleukin 18 (IL-18), neutrophil gelatinase-associated lipocalin (NGAL), and cystatin C-that may be able to predict AKI more effectively and faster than serum creatinine levels. In addition, study researchers will also determine if changes in these biomarkers can predict the severity of AKI more successfully than serum creatinine tests. This study will enroll people undergoing CABG or heart valve surgery at Yale-New Haven Hospital. Before the surgery and once a day for 5 days after the surgery, blood and urine collection will occur. Study researchers will also review participants' medical records. Twelve months after hospital discharge, participants will return to the clinic for a follow-up visit for repeat blood and urine collection and to complete questionnaires. A portion of blood will be saved for future genetic testing; this is optional.