Association of Routine Spot Urine Sodium Assessment with Early Decongestion and Clinical Outcomes in Patients Hospitalized for Worsening Heart Failure: A Prospective Cohort Study

Background: Early assessment of natriuretic response may identify patients with an inadequate response to intravenous loop diuretics. We examined whether introducing routine spot urine sodium assessment was associated with decongestion and short-term outcomes in patients hospitalized for worsening heart failure. Methods and Results: In this prospective, single-center, sequential-period cohort, 102 consecutive patients were enrolled during a standard-care period (n = 51) and a subsequent routine urine sodium assessment period (n = 51). Congestion was assessed at admission, 24, 48, and 72 h, and discharge using the 0- to 10-point ADVOR score; successful decongestion was defined as a score of 0 or 1 at 72 h. During the assessment period, spot urine sodium was measured before and 2 h after the initial intravenous diuretic. Successful decongestion occurred in 0% versus 45.1% of patients, respectively (p < 0.001). Mixed-effects analysis showed a more favorable congestion trajectory during the assessment period from 48 h onward. Two-hour urine sodium discriminated successful decongestion, with an apparent AUC of 0.965 (percentile bootstrap 95% CI, 0.904–1.000). An exploratory threshold of ≥69 mmol/L had 91.3% sensitivity and 96.4% specificity. The restricted acute kidney injury endpoint occurred in 9.8% of both groups. Ninety-day heart failure-related events occurred in 39.2% versus 5.9% (unadjusted hazard ratio, 0.128; 95% CI, 0.038–0.432). Conclusions: Routine spot urine sodium assessment was associated with a more favorable decongestion trajectory and fewer short-term heart failure-related events. The nonrandomized design, treatment differences, and limited event count preclude causal inference; these findings are hypothesis-generating.