Contrast-induced nephropathy in invasive cardiology

Contrast-induced nephropathy (CIN) is an acute renal injury due to the renal toxicity of iodinated contrast media. It is classically defined as a relative (≥25%) or absolute (≥0.5 mg/dl; 44 μmol/l) increase in serum creatinine from baseline value. CIN accounts for 10 to 15% of hospital-acquired acute renal failure and may rarely lead to irreversible renal function loss. Following percutaneous coronary intervention, reported incidence of CIN varies between 0 to more than 20%, depending on the prevalence of risk factors and used definition. Nowadays, the diagnosis of CIN relays on serum creatinine monitoring, although it is a late marker of acute kidney injury. Given the expanding number of percutaneous coronary interventions made in outpatient settings and the morbidity and mortality associated with CIN, early detection of CIN is of utmost clinical relevance. Several plasmatic and urinary biomarkers have been studied in that view, with plasmatic cystatine-C and urinary NGAL being the most promising. As no treatment specifically targets CIN once it develops, the main goal for clinicians remains prevention, with hydration status optimisation being the only proven strategy to date. Here, we will review the recent evidence concerning CIN, its incidence, proposed early diagnostic biomarkers, as well as its treatment and prognostic implication.