Renal resistive index (RRI) as a predictor of diuretic response in acute decompensated heart failure (ADHF)

Background Acute decompensated heart failure (ADHF) is a leading cause of hospitalization and is commonly accompanied by renal dysfunction and variable responsiveness to loop diuretics. Identifying patients at risk of poor diuretic response early in the course of illness remains a clinical challenge. The renal resistive index (RRI), a Doppler-derived ultrasonographic measure of intrarenal vascular resistance, has been recently recognised as a non-invasive marker of cardiorenal interactions. Aim and Objectives The aim of this study was to investigate the prognostic utility of RRI in predicting diuretic response, worsening renal function (WRF), and clinical outcomes among patients admitted with ADHF. Methods In this prospective observational study, 84 consecutive patients admitted with ADHF between July 2025 and January 2026 were enrolled. Renal Doppler ultrasonography was performed within 24 hours of admission to measure RRI. Clinical, laboratory, echocardiographic, and diuretic–response parameters—including 6–hour urine output, urinary sodium concentration, and a weight–based diuretic response index—were collected. Associations between RRI, diuretic response, WRF, and outcomes were analysed. Results The mean age of the study population was 57.6 ± 13.2 years, and 73.8% were male. The mean admission RRI was 0.689 ± 0.08. Higher RRI values were consistently associated with impaired diuretic responsiveness, reflected by lower early urine output, reduced urinary sodium excretion, and a diminished weight–based diuretic response index. Poor diuretic response occurred in approximately 25% of patients. WRF developed in 23% of patients. In–hospital mortality occurred in 9.5% of patients, 30–day readmission in 10.7%, and post–discharge mortality in 5.3%. Elevated RRI values were significantly associated with a higher risk of WRF and with adverse clinical outcomes. RRI correlated strongly with poor diuretic response (r = 0.591, p < 0.001) and inversely with urinary sodium (r = −0.448, p < 0.001). ROC curve analysis of the RRI demonstrated excellent predictive performance for poor diuretic response (AUC = 0.894), with an optimal cutoff of 0.718. Conclusions RRI is a promising non-invasive predictor of diuretic responsiveness and WRF in ADHF. Elevated admission RRI identifies patients at risk for inadequate decongestion and adverse outcomes, supporting its use for early risk stratification and individualized diuretic management.