BackgroundPreexisting impaired renal function (IRF) and contrast-induced nephropathy (CIN) after percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI) are important prognostic parameters, but it is unknown whether delayed PCI is still beneficial for STEMI patients with IRF.MethodsA retrospective single-center cohort study was performed in 164 patients who presented at least 12 h after symptom onset, and were diagnosed with STEMI and IRF. They were assigned to two groups to receive PCI plus optimal medical therapy (OMT) and OMT alone respectively. Clinical outcomes at 30 days and 1 year were compared between two groups, and hazard ratio for survival was analyzed using Cox regression model. A power analysis demanded 34 patients in each group to produce a power of 90% and a P value of 0.05.ResultsThe 30-day mortality was significantly lower in PCI group (n = 126) than in non-PCI group (n = 38) (11.1% versus 28.9%, P = 0.018), while there was no significant difference in the 1-year mortality and incidence of cardiovascular comorbidities between the two groups. Cox regression analysis showed that patients with IRF didn’t benefit from receiving PCI on survival rate (P = 0.267).ConclusionsDelayed PCI is not beneficial on one-year clinical outcomes for STEMI patients with IRF.