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

Background: 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.

Methods: 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.

Results: 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.

Conclusion: 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.