Impact of Transient or Persistent Contrast-induced Nephropathy on Long-term Mortality After Elective Percutaneous Coronary Intervention

Contrast-induced nephropathy (CIN) is associated with increased long-term mortality. However, it is still controversial whether CIN is the cause of increased mortality or merely a marker of high-risk patients. The current study population included 5,516 patients who underwent their first elective percutaneous coronary intervention (PCI) in the Coronary REvascularization Demonstrating Outcome Study in Kyoto registry cohort-2. CIN was defined as an elevation in the peak serum creatinine (SCr) of ≥0.5 mg/dl from the baseline within 5 days after PCI. CIN, seen in 218 patients (4.0%), was independently associated with an increased long-term mortality risk (hazard ratio [HR] 1.43, 95% confidence interval [CI],1.11 to 1.83; p = 0.005). SCr data at 1 year (180 to 550 days) after PCI were available in 3,986 patients, who were subdivided into persistent CIN (follow-up SCr elevation ≥0.5 mg/dl: n = 50 [1.3%]), transient CIN (follow-up SCr elevation <0.5 mg/dl: n = 90 [2.3%]), and non-CIN (n = 3,846 [96.5%]). In the landmark analysis at 1 year after PCI, 524 patients (13.1%) died during a median follow-up of 1,521 days. After adjustment for the 37 confounders, persistent CIN, but not transient CIN, was significantly correlated with a higher long-term mortality risk compared with non-CIN (HR 1.84, 95% CI 1.12 to 3.03; p = 0.02, and HR 1.11, 95% CI 0.71 to 1.76; p = 0.6, respectively). In conclusion, only persistent CIN was independently associated with increased long-term mortality.