Prognostic value of post-discharge urinary sodium levels following an admission for acute heart failure

Introduction

Acute heart failure (AHF) is associated with high rates of mortality and rehospitalization after discharge. Impaired natriuresis is a hallmark of AHF and reflects persistent congestion and neurohormonal activation. However, the prognostic significance of urinary sodium levels after hospital discharge is unclear.

Purpose

To evaluate post-discharge urinary sodium levels following an admission for AHF and their association with long-term clinical outcomes.

Methods

In this prospective and observational study, one hundred consecutive patients with AHF admitted to the Cardiology Department from February to June 2024 were included. Blood and urine samples were performed at admission, discharge and two weeks after discharge. Patients were divided into two groups by urinary sodium levels: <50 mEq/L -group 1- and >50 mEq/L -group 2; and they were followed for one year. Association between urinary sodium levels and outcomes was assessed using survival analysis.

Results

A total of 85 patients fullfilled the inclusion criteria, with 40% classified in group 1 and 60% in group 2. Both groups had similar aged patients, although there were a higher proportion of women in group 1. Regarding comorbidities, obesity and atrial fibrillation/flutter were significantly more prevalent in group 1. Patients in group 1 required a longer duration of intravenous diuretic therapy, while lenght of hospital stay was similar between groups.

At discharge, significant differences were observed in guideline-directed medical therapy. Group 1 had lower use of angiotensin receptor-neprilysin inhibitors and sodium-glucose cotransporter-2 inhibitors compared with group 2. In contrast, loop diuretcis were prescribed more frequently in group 1 (97.1% vs 80%), suggesting a greater need for decongestive therapy.

In the analytical evaluation at two week follow-up, group 1 exhibited higher NT-proBNP levels (p = 0.044), with no differences in CA12.5 between groups. Urinary chlorine levels were lower in group 1.

Respect echocardiographic data, no differences in left ventricular ejection fraction were observed; however, a greater proportion of patients in group 1 had preserved ejection fraction (>50%). Althought right ventricular systolic function was similar in both groups; group 1 demonstrated higher systolic pulmonary artery pressure and more severe tricuspid regurgitation.

During long term follow-up, patients in group 1 experienced a higher rate of worsening heart failure hospitalizations (p= 0.005), higher mortality (p= 0.072) and a significantly worse composite endpoint of death or worsening heart failure hospitalization (p = 0.003).

Conclusion

Lower post-discharge urinary sodium levels identified patients at higher risk of long-term mortality and worsening heart failure rehospitalization after an admission for acute heart failure. Urinary sodium may represent a simple, non-invasive marker to improve post-discharge risk stratification in this population.Population dataFor image description, please refer to the figure legend and surrounding text.Clinical long-term outcomesFor image description, please refer to the figure legend and surrounding text.