Long-term Outcomes of Renal Function Following CTO PCI: Insights on Contrast Exposure.

BACKGROUND: The impact of contrast volume on long-term renal outcomes after chronic total occlusion (CTO) percutaneous coronary intervention (PCI) remains uncertain. The causal role of contrast exposure is increasingly questioned, particularly beyond the acute phase. OBJECTIVES: To evaluate the association between procedural contrast volume and long-term renal function deterioration in patients undergoing CTO-PCI. METHODS: This retrospective cohort study included consecutive patients undergoing CTO-PCI (2019-2025) with available baseline and ≥90-day follow-up creatinine. The main endpoint was persistent kidney dysfunction (≥25% decline in estimated glomerular filtration rate (eGFR)). Other relevant endpoints were Kidney Disease: Improving Global Outcomes (KDIGO) stage progression (≥1 stage), and rapid progression (≥2 stages). Contrast volume was analyzed as a continuous variable and by quartiles. Multivariable regression models and sensitivity analysis (using a ≥40%eGFR decline threshold and baseline chronic kidney disease) were performed. RESULTS: A total of 275 patients were included with a median follow-up of 3.3 years. Renal function significantly declined (median ΔeGFR: -17.0 mL/min/1.73 m²; p <0.001). Persistent kidney dysfunction occurred in 52.4% of patients, KDIGO stage progression in 60.7% and rapid progression in 12.0% Contrast volume (median 215 mL) was not independently associated with persistent kidney dysfunction (p = 0.267) and no dose-response relationship was observed across quartiles. Findings were consistent across models for ΔeGFR, KDIGO-based, subgroups and sensitivity analyses. Patient-related factors including age, male sex, hypertension, and diabetes emerged as independent predictors of renal decline. Notably, baseline renal function showed an inverse association with progression (p < 0.001), suggesting a "ceiling effect" in advanced stages. CONCLUSIONS: In patients undergoing CTO-PCI, contrast volume is not independently associated with long-term renal deterioration. Persistent kidney dysfunction appears primarily driven by patient-related factors rather than procedural contrast exposure.