Post-CABG renal injury, failure common in low AKI risk category
Among patients who have received coronary artery bypass grafting (CABG), postoperative renal injury and failure as defined by the RIFLE criteria are only seen in the group of patients categorized as low risk of acute kidney injury (AKI) by the THAKAR score, according to a study presented at the 23rd ASEAN Federation of Cardiology Congress (AFCC 2018) in Bangkok, Thailand.
On the other hand, the incidence of severe AKI is low, and AKI-related morbidity and mortality are reduced.
AKI is a common complication of CABG, associated with significant increases in both short- and long-term morbidity and mortality, the authors said. Therefore, the identification of preoperative risk factors for such a condition is an important component in cardiovascular surgery.
The hospital-based, cross-sectional, descriptive study included 90 CABG patients, among whom 60 percent were aged <60 years and 75 percent were male. THAKAR score, which is also known as the Cleveland Clinic score, was calculated based on the relevant variables for each patient and consisted of the following AKI risk categories: low, intermediate, high and very high. Meanwhile, RIFLE criteria classified AKI into the following stages of severity: non-AKI, risk, injury and failure.
Based on THAKAR sores, 43 patients were in the low risk category, 37 in intermediate, seven in high and three in very high. THAKAR risk factors included female sex, heart failure, left ventricular ejection fraction <35 percent, intraoperative aortic balloon pump use, chronic obstructive pulmonary disease, diabetes mellitus, creatinine levels, emergency case and type of surgery. [AFCC 2018, abstract P030]
According to the RIFLE criteria, 76 were in the non-AKI class, 11 in the risk class, two in the injury class and only one in the failure class. The THAKAR scores and RIFLE criteria showed a fair level of agreement in predicting AKI (Kappa value, 0.21).
Deaths occurred in two patients in the non-AKI class—one due to postoperative acute myocardial infarction and another due to ventricular tachycardia—and in one of the 14 patients with AKI due to multiorgan failure. AKI resolved in the remaining 13 patients before hospital discharge, among whom one with very high THAKAR score was frequently readmitted for congestive heart failure and renal insufficiency syndrome.
Given that the level of agreement in predicting AKI following cardiovascular surgery between the RIFLE criteria and THAKAR scores is merely fair, the authors highlighted a need for more conclusive data.