New updates to the contrast-associated acute kidney injury (CA-AKI) risk score successfully identify patients at higher risk of acute kidney injury (AKI) and 1-year all-cause mortality and bleeding. Findings from the research team externally validate the Mehran CA-AKI scoring method using the Kidney Disease Improving Global Outcomes (KDIGO) criteria in a large cohort of acute coronary syndrome (ACS) patients undergoing invasive management. The authors also suggested that the risk of CA-AKI was overestimated in previous risk models that were hindered by limited practical use, less reliable CA-AKI definitions, or poor performance in specific clinical scenarios. “The updated CA-AKI risk score had a moderate discrimination, which [was] further improved by the inclusion of procedural variables,” summarized the paper’s authors, who were led by Antonio Landi, MD, from Ente Ospedaliero Cantonale the University of Italian Switzerland, both in Lugano, Switzerland. “The risk score performance was numerically greater with the KDIGO criteria than the AKI-MATRIX primary definition and in patients receiving femoral access or bivalirudin than radial access or UFH [unfractionated heparin].” The study, which appears in the Aug. 14 issue of JACC: Cardiovascular Interventions, also notes that the score overestimated the AKI risk with the KDIGO criteria and underestimated it with the MATRIX primary definition of AKI. According to the researchers, this reflected the use of more (e.g., the KDIGO definition) or less stringent (e.g., the MATRIX primary definition) AKI criteria. MATRIX results The Minimizing Adverse Haemorrhagic Events by Transradial Access Site and Systemic Implementation of angioX (MATRIX) trial enrolled 8,201 patients who had complete creatinine values and no end-stage renal disease. Out of this population, CA-AKI occurred in 5.5% of the patients, with a stepwise increase of CA-AKI rates from the lowest to the highest of the four risk categories. Further findings reveal that the receiver-operating characteristic area under the curve was 0.67 (95% confidence interval [CI]: 0.64-0.70) with model 1 and 0.71 (95% CI: 0.68-0.74) with model 2. CA-AKI risk was systematically overestimated with both models (Hosmer-Lemeshow goodness-of-fit test: P<0.05), says the paper, which was also published Monday online. The 1-year risks of all-cause mortality and bleeding were higher in CA-AKI patients (hazard ratio [HR]: 7.03; 95% CI: 5.47-9.05) with model 1 and (HR: 3.20; 95% CI: 2.56-3.99) with model 2. There was a gradual risk increase for mortality and bleeding as a function of the CA-AKI risk category for both models. “The discriminative ability of the score was consistent for transient or persistent AKI prediction with both models,” the paper’s authors added. “Among ACS patients undergoing invasive management, the occurrence of CA-AKI remained associated with higher risks of 1-year mortality and bleeding with a gradual increase of risk as a function of the CA-AKI category.” Editorial comment critique Andrew M. Goldsweig, MD, MS, from the Baystate Medical Center, Springfield, Massachusetts, and Mahmoud Ismayl, MD, from the Mayo Clinic School of Medicine, Rochester, Minnesota, noted that CA-AKI following percutaneous coronary intervention (PCI) doubled the risk for mortality at 2 years. In an accompanying editorial comment, the two commentators hailed the research as providing further evidence in support of widespread implementation of CA-AKI risk prediction as well as the easy to calculate and highly predictive Mehran score. The commentators also pointed out that the MATRIX trial excluded patients with stage 4 and 5 CKD (estimated glomerular filtration rate <30 mL/min/1.73 m2) or on hemodialysis. According to them, this limited the generalizability of the study’s findings in patients with advanced CKD. They concluded with a number of recommendations that included electronic medical record systems that should automatically compute the CA-AKI risk for patients presenting to cardiology clinics. Also, smartphone apps should be used widely to compute the CA-AKI risk when patients with ACS are seen in the emergency department, the editorialists wrote. Trial methodology In total, 8,404 patients were enrolled in the MATRIX trial, of whom 203 patients (2.4%) were excluded. This patient population had a mean age of 65.7±11.8 years, of whom 2,110 (26%) were ≥75 years. This population contained 6,032 (74%) male subjects. The baseline and procedural characteristics of the included MATRIX population were stratified by risk score quartiles (Low Risk (n=155); Moderate Risk (n=3,738); High Risk (n=3,965); and Very High Risk (n=343). The median duration of follow-up in the overall cohort was 365 days (interquartile range [IQR]: 365-365 days). Independent predictors of KDIGO–based acute kidney injury and the impact of CA-AKI on 1-year mortality and bleeding were also investigated. The primary endpoint of the MATRIX study was the rate of CA-AKI defined according to the KDIGO criteria. The research team also implemented the AKI-MATRIX primary definition based on either an absolute (>0.5 mg/dL) or a relative (>25%) increase from baseline in serum creatinine levels during hospitalization. Sources: Landi A, Chiarito M, Branca M, et al. Validation of a Contemporary Acute Kidney Injury Risk Score in Patients With Acute Coronary Syndrome. JACC Cardiovasc Interv 2023;16: 1873–1886. Goldsweig AM, Ismayl M, et al. A Seatbelt for the Kidney During Coronary Intervention. JACC Cardiovasc. Interv 2023;16:1887–1888. Image Credit: AKDIM_DESIGN – stock.adobe.com