SODIUM-HF: Study Of Dietary Intervention Under 100 Mmol In Heart Failure

By Jamie E. Diamond, MD on

Key points:

  • Sodium-HF sought to determine whether dietary sodium reduction reduces the morbidity or mortality associated with heart failure (HF) in the largest randomized trial testing dietary sodium in HF patients to date
  • Dietary sodium reduction (to a target of <1500 mg/day) in HF patients did not reduce the clinical composite outcome of all-cause mortality, cardiovascular-related hospitalization, or cardiovascular-related emergency department visits compared with usual care over 12 months
  • NYHA functional class and KCCQ scores were modestly improved in low sodium vs. usual care groups, indicating signal for better quality of life in those patients adhering to sodium restricted diets
  • Investigators conclude that clinicians and patients should consider a dietary intervention similar to other medical therapies and balance the potential benefits on an individual basis

Numerous cardiac encounters among heart failure (HF) patients are linked to dietary salt indiscretion. As a result, cardiology providers spend a great deal of time and effort convincing their heart failure patients to reduce their sodium intake. Recommendations for sodium intake are inconsistent for HF patients with goal targets that range from <2,000 to <3,000 mg/day according to various cardiac societies. Does decreasing the amount of sodium you eat really contribute to heart failure outcomes? The study’s principal investigator, Justin Ezekowitz, MBBCh at the University of Alberta recognized that there is a lack of evidence on the impact of decreased dietary sodium on clinical events in HF patients. The SODIUM-HF trial, a multicenter open-label clinical trial, therefore sought to answer that question by determining the efficacy of a low sodium containing diet in ambulatory patients with chronic HF.

SODIUM-HF is an international, pragmatic, randomized, controlled trial that enrolled patients who were 18 years of age or older with a confirmed diagnosis of chronic NYHA class II or III heart failure (both preserved and reduced ejection fractions) on optimally tolerated medical therapy. Patients were excluded if they had average dietary intake of <1500mg/day, serum sodium <130mmol/L, renal or hepatic failure, thyroid disorders, cardiac device or revascularization procedure in the prior 3 months, recent cardiac hospitalization, active malignancy or moderate dementia.

Trial participants were randomized to the experimental arm which enforced a low sodium diet of <100mmol (<1500 mg/day) or usual care arm which involved general advice to limit dietary sodium as is typically provided during routine clinic practice. Those in the experimental arm were provided with meal plans and menus that varied according to patients’ energy requirements, energy distribution and extent of sodium restriction compared with their normal diet. Sodium intake was monitored through 3-day food records and patients were followed closely at clinic visits every 3 months where vital signs, NYHA class and quality of life were assessed. The total intervention period was 12 months and participants were followed up thereafter for an additional 12 months, though the trial was stopped prematurely as a result of the COVID-19 pandemic.

The SODIUM-HF trial took place in 26 sites across 7 countries. Amongst the 806 patients included in analyses, the baseline characteristics were evenly distributed amongst the low sodium diet and usual care groups with ~33% of women in each group. Results showed that patients in the experimental group had significantly lower sodium intake with 415mg/d reduction compared to the usual group (p<0.0001). Weight, blood pressure, and energy intake (in calories/day) were similar amongst the two groups over a twelve-month period. The important results, presented at the 2022 American College of Cardiology Scientific Sessions and simultaneously published in the Lancet on April 2nd, 2022, showed that there was no significant difference in the primary outcome (cardiovascular related hospitalization or emergency department visit or all-cause mortality) between groups at 12 months (HR 0.89, 95% CI 0.63-1.26, p=0.53). Though there was a trend towards decreased cardiovascular hospitalizations in the low sodium group this did not meet statistical significance (HR 0.82, 95% CI 0.54-1.24, p=0.36). Secondary outcomes revealed that though there was an improvement in quality of life amongst the low sodium group as assessed by the KCCQ score, there was no significant difference in the 6 minute walk test between groups at 12 months. NYHA functional class also improved marginally in the low sodium group. Limitations to the trial included lower than anticipated event rate (due in part to early termination of the study), lack of biomarker collection, and lack of blinding due to pragmatic nature of the trial. Additionally, whether a greater reduction in dietary sodium might affect results is unknown. Investigators conclude that the dietary intervention to reduce sodium intake did not lead to a reduction in clinical events, though might improve quality of life in HF patients. As a result of these outcomes the recommended dietary sodium goal for HF patients remains unknown and should be individualized to patients based on their physiology and symptoms.