5MinuteConsult Journal Club

Salt Restriction May NOT Improve Outcomes in Class 2-3 Heart Failure

Reference

Lancet 2022 Apr 2; [e-pub]. (https://doi.org/10.1016/S0140-6736(22)00369-5)

Outcomes

This international, open-label, randomized, controlled trial in six countries (Australia, Canada, Chile, Colombia, Mexico, and New Zealand) compared “low salt diet” of < 1,500 mg/day of salt to “usual care” adults with chronic heart failure (New York Heart Association [NYHA] functional class 2–3), who were receiving optimal guideline-directed treatment.

At 12 months, the primary outcome (composite of cardiovascular-related admission to hospital, cardiovascular-related emergency department visit, or all-cause death) was not statistically different in the 2 groups, occurring in 15% in the low sodium diet group and 17% in the usual care group (hazard ratio [HR] 0·89 [95% CI 0·63–1·26]; p=0·53).

All-cause death, cardiovascular-related hospitalization, and cardiovascular-related emergency department visits were not statistically different.

Conclusions

Low salt diets, in those with NYHA class 2-3 heart failure receiving optimized heart failure diets did not improve composite or individual outcomes.

Discussion

This study gets to the heart of evidence-based medicine. Fluid overload is the pathway to severe adverse events in those with heart failure. Salt restriction ‘logically’ would lower the risk of retaining excess fluid. So, it stands to reason salt restriction would lower adverse heart failure events. But in this study, it does not. Why? One can only guess at the mechanism of action; maybe disrupting the renin-angiotensin pathway?

We have known for a while that in non-heart failure patients, aggressive salt restriction leads to elevated (yes, elevated) blood pressure. Over 4,000 mg/day of salt is definitely unhealthy, but so is too little. What is optimum? Likely ~2,400 mg/day for the average person, which equals about 1 teaspoon of salt (remember, salt is not just sodium). And for heart failure patients, 1,500 – 2,000 mg/day.

And, it isn’t the salt shaker on your table that is problematic. Most dietary salt we eat comes from processed foods (breads, soups, processed meats, etc.). An aggressive shake of your salt shaker equals around 200 mg of sodium.

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Contributed by Frank J. Domino, October 26, 2022