Association between vascular access route and exceedance of the maximum allowable contrast dose with medium- to long-term renal function decline in patients undergoing repeated PCI

Background and Aims Contrast-induced nephropathy remains a challenge in cardiovascular procedures. Minimization of contrast volume and the use of a transradial vascular access whenever feasible are considered key modifiable risk factors for acute kidney injury. Contemporary approaches emphasize individualized assessment, such as the maximum allowable contrast dose (MACD), which accounts for body weight and baseline renal function. However, whether these factors also contribute to a decline in medium- to long-term renal function remains unclear. Therefore, the aim of this analysis was to investigate this association in patients undergoing repeated percutaneous coronary interventions (PCI). Methods In this subgroup analysis of a retrospective single-center study, patients with repeated PCI between 2003 and 2023 with an interval of ≥7 and ≤365 days between procedures were included. All data, including the chosen vascular access for the initial PCI, were extracted from hospital records. The individual MACD was calculated for each patient according to the original formula (5 × body weight [kg] / serum creatinine [mg/dL]), with a maximum dose of 300 mL. Renal function was classified according to the Kidney Disease: Improving Global Outcomes (KDIGO) staging system. The primary endpoint was the risk of KDIGO stage progression at readmission, excluding patients initially classified as stage G5. Secondary endpoints were associations with eGFR at readmission. Results In 1,814 (27%) of the 6,714 patients included, the contrast volume administered during PCI exceeded the individual MACD. The median MACD was 300 mL in both groups. The median contrast volume administered was substantially higher in the exceedance group (400 mL vs. 200 mL in the non-exceedance group). These patients had lower mean eGFR (68.5 ± 26.1 vs. 76.6 ± 19.0 mL/min/1.73 m²) at baseline. Other baseline characteristics were similar between groups. At readmission, mean eGFR was 69.25 ± 24.3 mL/min/1.73 m² in the exceedance group and 73.24 ± 20.4 mL/min/1.73 m² in the non-exceedance group. Univariable analyses showed no statistically significant association between MACD exceedance and increased risk of KDIGO stage progression (HR 0.93; 95% CI: 0.83-1.04) or eGFR (Estimate: 0.22; 95% CI: -0.79-1.24) at follow-up, which was confirmed in multivariable analyses. In 2,500 patients (37.2%) the initial PCI was performed via radial access. While there was a trend towards lower risk for renal impairment at readmission, ultimately no statistically significant association was found (KDIGO: HR 0.91; 95% CI: 0.82-1.01; eGFR: Estimate 0.79; 95% CI: -0.17-1.75). Conclusion Neither the chosen vascular access route nor exceeding the individual MACD during PCI were associated with a decline in medium- to long-term renal function in patients with repeated interventions within one year.