Baseline high renal resistance index is associated with worsening of renal function in patients undergoing cardiac surgery

Abstract Renal resistance index (RRI) is a parameter which is easily evaluable by the echo Doppler technique and which has been demonstrated to predict worsening of renal function (WRF) in patients affected by chronic heart failure as well as among those undergoing coronary angiography. The aim of this study was designed to evaluate the role of the RRI in predicting WRF after cardiac surgery. Methods Thirty–one patients were enrolled. Their clinical characteristics are shown in Table 1. All patients underwent cardiac surgery. Before surgery, RRI was evaluated according to Peurcelot’s formula by renal interlobular arteries pulsed Doppler. WRF was defined as an increase in serum creatinine of > 0.3 mg/dl associated with a change > 25% or the need of renal replacement therapy due to severe acute kidney injury. Results Among the patients in 12 WRF occurred, in 10 a worsening of creatinine serum levels and in 2 a severe AKI requiring RRT were observed. As shown in Table 1, RRI and the presence of peripheral artery disease were the only parameters which were significantly different among patients with and without WRF, whereas no difference in GFR values was observed. Baseline RRI showed a significant AUC of 0.74 (95% CI, 0.55–0.93) whereas baseline GFR of 0.52 (95% CI, 0.28–0.75) was not significant. Conclusions Among patients with WRF after cardiac surgery an increased RRI but not a different baseline GFR is observed. This parameter could allow a more accurate stratification of the risk of cardiorenal syndrome worsening among patients candidated to cardiac surgery.