Post-diuretic Spot Urine Sodium Assessment in Acute Heart Failure: a Retrospective Analysis.

Aims: To provide real-world data on post-diuretic spot urine sodium concentration (UNa) assessment in acute heart failure (AHF) and its implications for treatment. Methods and Results: Automated query of the electronic medical record identified patients admitted to the cardiac intensive care unit of a single tertiary care hospital between November 2018 and December 2021, who received intravenous loop diuretics. Detailed manual chart review confirmed the AHF diagnosis. Stratification was performed based on whether post-diuretic UNa was assessed within 24 h of admission. AHF was confirmed in 340/380 identified patients. Post-diuretic UNa was assessed in 117 (34%), more frequently when ejection fraction was reduced and heart failure more advanced. Patients with versus without post-diuretic UNa assessment received higher doses of intravenous loop diuretics and more frequently acetazolamide and thiazide-like diuretics (p < 0.001 for all), resulting in similar urine output despite more advanced heart failure [2,488 mL (1,740-4,033 mL) vs. 2,400 mL (1,553-3,250 mL), respectively; p = 0.170]. Diuretic therapy remained more intense at discharge in the post-diuretic UNa group, with also a higher prescription rate of angiotensin-neprilysin inhibitors (p = 0.021). Serum creatinine increases/decreases were similarly frequent irrespectively from UNa assessment, with more dynamic changes observed in patients with UNa <= 80 mmol/L versus >= 81 mmol/L. After adjustments for baseline characteristics, the risk for death or heart failure readmission was similar in patients with versus without UNa assessment [HR (95%CI) = 1.43 (0.88-2.32); p = 0.150]. Conclusion: Post-diuretic UNa assessment in AHF was associated with more intense diuretic regimens, preserving urine output despite its use in a sicker population.