Acute kidney injury among patients aged over 80 years after percutaneous coronary intervention: a multicenter, retrospective cohort study

We aimed to investigate the incidence and risk factors of acute kidney injury (AKI) after percutaneous coronary intervention (PCI) in the oldest-old patients (≥80 years), particularly among those with baseline renal insufficiency and peri-operative hydration. This retrospective cohort study included patients ≥80 years undergoing PCI at two tertiary hospitals in China (hospitalized between January 2020 and December 2024). Baseline renal dysfunction was defined as eGFR < 60 mL/min/1.73 m² on admission. The primary endpoint was AKI event after PCI according to KDIGO criteria. Secondary endpoints included in-hospital mortality, renal replacement therapy, and length of hospital stay. Logistic regression was applied to identify AKI risk factors. Restricted cubic splines (RCS, 4 knots) were used to explore the dynamic risk magnitude for AKI as baseline eGFR changes, adjusting for multivariable. Among the 995 patients included in the final analysis, the incidence of baseline renal insufficiency was 35.9% and that of AKI was 13.8%. Logistic regression showed that STEMI, NSTEMI, acute heart failure, baseline renal insufficiency, a higher neutrophil-to-lymphocyte ratio (NLR), and anemia were independent risk factors for AKI. Among those with baseline renal insufficiency, AKI incidence was 29.7%, and lower baseline eGFR, elevated NLR, and preoperative diuretic use were independent risk factors for AKI. RCS analysis revealed that the AKI risk was significantly increased when eGFR < 67.4 mL/min/1.73 m², regardless of hydration therapy. Patients ≥ 80 years old with baseline renal failure confronted higher AKI risk after PCI procedure. Comprehensive strategies beyond hydration may be needed for AKI prevention in this fragile population.