Low-Sodium Diet and Mortality in Patients with Heart Failure with Worsening Kidney Function during Hospitalization

Background: Sodium restriction can help prevent and alleviate congestion in patients with heart failure (HF), but the benefits of sodium restriction are controversial. Patients with worsening renal function (WRF) during treatment of heart failure have worse outcomes and may benefit from more strict volume control. We investigated the prognostic impact of sodium restriction in patients hospitalized with HF focusing on WRF. Methods: This retrospective cohort study included patients hospitalized for HF from 2000 to 2019. WRF was defined as a decrease in estimated glomerular filtration rate (eGFR) >20% from admission at any point during hospitalization. The difference in weight from admission to discharge was used to estimate the degree of decongestion. Low-sodium diet status was estimated from the diet prescription at the time of discharge. The primary outcome was all-cause mortality. Results: In a total of 1,079 patients, 566 (52.5%) developed WRF and 325 (30.1%) consumed a low-sodium diet. There was no difference in baseline characteristics between the low-sodium diet and control groups, except for eGFR (low-sodium diet vs control: 58 vs 66 mL/min/1.73 m2; p=0.001). The proportion of low-sodium diets did not differ between the WRF and no-WRF groups (31% vs 29%; p=0.548). The low-sodium diet group lost more weight than the control group (-2.2 vs -1.9 kg; p=0.015) during hospitalization. During a median follow-up of 33.1 months (IQR 4.7–64.5), 229 (21.2%) patients died. Low-sodium diet was associated with lower mortality in the WRF group (HR 0.563, 95% CI 0.385–0.822, p=0.003), but not in the no-WRF group (HR 0.922, 95% CI 0.563–1.510, p=0.747). Low-sodium diet showed association with lower mortality after multivariable adjustment in the WRF group (adjusted HR 0.668, 95% CI 0.452-0.987, p=0.043). Conclusion: Low-sodium diet could be beneficial for patient with HF requiring hospitalization, especially with WRF.