Sodium restrictions in heart failure

Clinical question

Does sodium restriction improve outcomes in patients with chronic heart failure (CHF)?

Bottom line

In patients with CHF, restricting dietary sodium to less than 2 g/day does not reduce death or hospitalization compared with 2 to 3 g/day.

Evidence

• Four systematic reviews assessed dietary sodium restriction in patients with HF (5 to 17 RCTs, 479 to 1683 participants).^1-4

  • - In the most comprehensive systematic review,¹ sodium restriction was less than 2 g/day in 11 RCTs and 2 to 3 g/day in 6 RCTs; usual care ranged from 2 to 5 g/day (when reported) with a duration of 1 week to 1 year; there were 13 RCTs of outpatients and 4 of inpatients.

    • — There were no significant differences in all-cause or cardiovascular death or hospitalizations.

  • - Sodium restriction increased mortality and-or hospitalization in 3 reviews and meta-analyses.^2-4

    • — Results^5,6 driven by 2 to 4 RCTs from the same author group had several issues, such as duplicate reporting, inadequate background medications, very high furosemide doses (250 to 1000 mg/day), and tight fluid restriction (<1 L/day) that are not representative of current practice.

• The largest (806 patients) unblinded RCT⁷ of patients with CHF with any ejection fraction (>99% New York Heart Association class 2 to 3) and baseline dietary sodium intake of about 2.2 g/day randomized patients to either a dietitian targeting sodium intake of less than 1.5 g/day (achieved roughly 1.7 g/day) or usual care (achieved roughly 2.1 g/day).

  • - At 1 year, death or cardiovascular emergency department visits or hospitalizations: 15% versus 17% (usual care), not statistically different.

• Sodium restriction does not consistently improve HF symptoms or quality of life.^1,4,7

Context

• Sodium restriction theory: Renin-angiotensin-aldosterone system activation in HF causes sodium and water retention. Excess sodium restriction could exacerbate activation.⁵

• A previous iteration initially suggested sodium restriction worsened outcomes, but was later updated after the original supporting systematic review was retracted.⁵

• Canadians consume an average of 2.8 g/day of sodium.⁸

• Canadian guidelines recommend restricting sodium intake to 2 to 3 g/day, whereas American and European guidelines recommend avoiding “excess” sodium intake without defining specific amounts.⁹

• In patients hospitalized for acute HF, restricting sodium (<800 mg/day) and fluids (<800 mL/day) increased thirst without reducing signs or symptoms of congestion.¹⁰

Implementation

Evidence regarding specific targets for sodium and fluid intake in HF is lacking. Canada’s food guide recommends limiting processed foods and preparing meals and snacks using ingredients with little to no added sodium.¹¹ Educate patients with HF on these points without specific (especially strict) restrictions. In patients who have symptomatic hypotension or a rise in creatinine levels of more than 35% after starting or increasing the dose of an HF medication, assess sodium and fluid intake for excess restrictions and diuretic doses and consider adjustments. Issues may resolve while maintaining HF medications that improve outcomes.