The investigators are proposing a prospective, randomized, double blinded, placebo-controlled single center study evaluating the role of co-administration of oral sodium chloride (NaCl) with intravenous diuretics in patients hospitalized with acute decompensated heart failure. The investigators are approaching this study with the hypothesis that the use of oral sodium chloride leads to improved effective diuresis (as measured by weight loss) and renal function as compared to placebo in patients hospitalized with acute decompensated heart failure undergoing aggressive intravenous diuretic therapy.

Dietary sodium restriction is a common therapeutic intervention in the management of patients hospitalized with decompensated heart failure. This is despite limited supportive data and inconsistent society guidelines.1-3 Randomized clinical trial data has shown that dietary sodium restriction in patients hospitalized with heart failure was not associated with differences in weight, clinical congestion, time to clinical stability but was associated with increased thirst.4 Numerous studies demonstrate that sodium restriction is associated with increased Renin-Angiotensin-Aldosterone System (RAAS) activation as well as increases in inflammatory markers.5,6 These findings challenge of the role of sodium restriction in hospital management of heart failure and have lead to trials that consider a therapeutic role of providing sodium to patients with acute heart failure for its effect in attenuating neurohormonal activation during aggressive diuresis. A central example is the SMAC-HF study from Italy, which showed that in 1771 patients with acute New York Heart Association (NYHA) class IV heart failure, the addition of hypertonic saline (150ml of 1.4%-4.6% NaCl twice a day in addition to diet liberalization led to statistically significant increased urine output and weight loss in addition to reductions in creatinine, length of stay, mortality and readmissions.7 These findings are controversial but similarly favorable results with the use of hypertonic saline in aiding diuresis have been seen in Japan with improved diuresis with continuous hypertonic saline infusions.8 Despite these results, use of sodium chloride supplementation in acute heart failure remains limited. This may be because the practice challenges ingrained clinical practice, but a more likely reason is that the manner of sodium chloride delivery in these trials (hypertonic saline) is often reserved for the Intensive Care Unit (ICU) setting and central venous access for delivery. While small volumes of hypertonic saline are likely safe to be administered in a non-ICU setting, the results would be more broadly applicable and utilized if the manner of sodium supplementation did not require intensive monitoring or central venous access, ie oral supplementation. Therefore, the purpose of the "Oral Sodium to Preserve Renal EfficiencY in Acute Heart Failure" (OSPREY-AHF) is to evaluate the efficacy and safety of oral sodium chloride supplementation compared to placebo in patients with acute decompensated heart failure. While the investigators are specifically interested in sodium chloride and its hypothesized role in attenuating a neurohormonally mediated diuretic resistance commonly seen in patients requiring high dose diuretic therapy, the investigators also intend that by focusing on oral sodium chloride supplementation the investigators may clarify the role of dietary sodium restriction in hospitalized patients with acute heart failure.

Inclusion Criteria:

• Age ≥ 18 years old AND
• Admitted to cardiology floor (non-ICU) with primary diagnosis of decompensated heart failure AND
• NT-proBNP >1000 ng/L AND
• Initiation of continuous furosemide infusion at a rate of 10 mg/hr or higher

Exclusion Criteria:

• Serum sodium (Na+) level less than 120 or greater than 145.
• Average Systolic Blood Pressure >180 mmHg or Diastolic Blood Pressure >100 mmHg over past 24 hours.
• Anticipated length of stay less than 72 hours.
• Use of vasopressin antagonist
• Current use of sodium chloride tablets
• Active diagnosis of diabetes insipidus
• Inability to tolerate oral diet or swallow pills
• Presence of malabsorptive gastrointestinal disorder (Crohn's disease, short gut syndrome)
• The use of iodinated radiocontrast material in the past 72 hours or anticipated use of intravenous contrast during the current hospitalization
• Admission with intention to transplant or implant permanent Ventricular Assistive Device
• Use of intravenous inotropes, vasopressors or vasodilators at enrollment
• A baseline estimated glomerular filtration rate <15 mL/min/1.73m² according to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula at the moment of inclusion
• Use of renal replacement therapy at time of enrollment

Enrollment to 90 days post enrollment

Limitations: single center trial, small sample size, heterogeneous baseline characteristics & degree of congestion, only powered for short term effects of NaCl supplementation, not powered for noninferiority analysis for change in weight, extra NaCl not continued after IV diuresis stopped, underpowered to fully assess significance of NaCl on safety, only spot urine collected (no 24-hour urine) & only 48 patients provided samples for serum biomarker analysis.

This is a double blind study. Subjects will be randomized to Sodium Chloride tablets and Placebos and picked up from pharmacy.