Persistent renal damage after contrast-induced acute kidney injury: incidence, evolution, risk factors, and prognosis

The temporal evolution of renal function in patients with acute kidney injury after contrast medium (CI-AKI) is not well known. The aim of this observational study was to evaluate the incidence, risk factors, and prognostic implications of persistent renal damage (RD) in patients with preexistent moderate-to-severe renal dysfunction.

From June 2003 to March 2008, 3986 patients underwent coronary angiography at our institution; 1490 of 3986 had an estimated creatinine clearance of <60 mL/min and were enrolled. CI-AKI was defined as an absolute increase ≥ 0.5 mg/dL over baseline serum creatinine within 3 days after the administration of contrast medium (iodixanol). In patients who developed CI-AKI, persistent RD was defined as a relative decrease of creatinine clearance ≥ 25% over baseline at 3 months. Patients whose creatinine clearance returned to baseline (or nearly) were classified as transient RD. The overall incidence of CI-AKI was 12.1%, and persistent RD occurred in 18.6% of CI-AKI patients. At Cox regression analysis, nephropathy risk score ≥ 17, left ventricular ejection fraction ≤ 30%, and increased value of serum creatinine ≥ 1.5-fold from baseline within 5 days were found to be significant risk factors for persistent RD. At 5 years, the incidence of death was significantly higher in patients with persistent RD than in both patients with transient RD (P=0.015) and those without CI-AKI (P=0.0001). A similar trend was observed for the combined end point of death, dialysis and cardiovascular events.

These results suggest that CI-AKI is not always a transient, benign creatininopathy, but rather a direct cause of worsening renal function. The occurrence of CI-AKI can identify patients at increased risk of cardiovascular events.