Two biomarkers of early acute kidney injury−plasmatic neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C−are not used in routine clinical practice in patients with ST-segment elevation myocardial infarction (STEMI) treated by percutaneous coronary intervention (PCI) because of a lack of supporting data.

To evaluate the predictive value of NGAL and cystatin C regarding the incidence of contrast-induced acute kidney injury (CI-AKI) and clinical outcomes after STEMI in patients treated by primary PCI.

Plasmatic NGAL and cystatin C were measured on admission, before any contrast exposure, in 701 unselected patients with STEMI. Associations between biomarker concentrations and incidence of CI-AKI (assessed at 48h), haemodialysis requirement at 1 year and all-cause mortality at 1 year were assessed by logistic regression analyses and receiver operating characteristic area under the curve analysis (c-statistic). Discrimination performance comparison was performed using the DeLong test.

NGAL and cystatin C had mild discrimination regarding CI-AKI, with c-statistics of 0.60 (P=0.001) and 0.60 (P=0.002), respectively. Combining NGAL and cystatin C did not improve their discrimination (c-statistic 0.61; P=0.001). There was no significant difference in discrimination between NGAL, cystatin C and baseline creatinine (P=0.57). Regression analyses showed no independent association between NGAL and CI-AKI, haemodialysis or 1-year mortality. Similarly, cystatin C was not associated with these clinical outcomes.

In this cohort of patients with STEMI treated by primary PCI, plasmatic NGAL and cystatin C did not provide additional value regarding CI-AKI prediction compared with known risk factors such as baseline creatinine.