Benefit of Salt Restriction in Heart Failure Uncertain

Megan Brooks

November 07, 2018

Despite "broad advocacy" for salt restriction in patients with heart failure, a new systematic data review finds no clear evidence that a low-salt diet will minimize complications or improve outcomes.

For inpatients with heart failure, there was no evidence of a significant clinical benefit in patients on a sodium-restricted diet. In chronic ambulatory heart failure, a modest and inconsistent trend toward symptom improvement was noted.

The study was published online November 5 in JAMA Internal Medicine.

A "Pause Moment"

Patients with heart failure have, in general, been told to lower their salt intake, Kamal R. Mahtani, from the Centre for Evidence-Based Medicine, University of Oxford, United Kingdom, told theheart.org | Medscape Cardiology.

Yet guidelines "appear to vary in the exact advice they give heart failure patients when it comes to reducing salt intake. Our research highlights a lack of robust, high-quality evidence available to support or refute current guidance, reflecting current uncertainty," said Mahtani.

This study is "worth contemplating" and provides a "pause moment," writes Clyde Yancy, MD, Northwestern University Feinberg School of Medicine, Chicago, in an accompanying editorial.

Among 2655 potentially relevant articles on heart failure and sodium restriction retrieved from several sources, including the Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE, only nine randomized controlled trials involving 479 patients were deemed worthy of inclusion in the review.

"We found no clinically relevant data on whether reduced dietary salt intake affected outcomes such as cardiovascular-associated or all-cause mortality, cardiovascular-associated events, hospitalization, or length of hospital stay," the authors report.

For outpatients with heart failure, there was no significant evidence of harm from a reduction of dietary salt intake but a trend toward some clinical improvements, such as in NYHA functional class.

"These findings suggest that current best practice should not be changed for this patient group. This suggestion is consistent with other evidence that lower salt intake is associated with minimum health risks and that reducing sodium intake may reduce the risk for morbidity and mortality due to cardiovascular disease," write Mahtani and colleagues.

The Painful Truth

However, they say "clinicians and policy makers should acknowledge the lack of evidence for this intervention in patients who may be reluctant to restrict salt intake and the social and economic feasibility of achieving reduced-salt diets in wider populations."

Restriction of salt intake for inpatients with acute heart failure has an even weaker evidence base than that for outpatients, the authors note.

"Most importantly," Mahtani told theheart.org | Medscape Cardiology, "when considering a lower-salt diet, patients with heart failure should discuss the evidence with their healthcare professional and come to a shared decision based on both the evidence and the individual circumstances of the patient."

"Better designed, pragmatic, and more extensive studies" on salt restriction in heart failure patients are clearly needed, said Mahtani.

We must make the painful deduction that the current evidence base addressing sodium restriction in heart failure is vacuous, lacks depth, and in some cases lacks integrity. Clyde Yancy

Yancy agrees. The "core issue here that resonates loudest is the absence of high-quality evidence. We must increasingly move away from any class I recommendations or the equivalent supported by expert consensus or nonrandomized data and not more firmly cemented with high-quality verifiable evidence," he says.

"We must make the painful deduction that the current evidence base addressing sodium restriction in heart failure is vacuous, lacks depth, and in some cases lacks integrity," he adds.

"The first step," he continues, is to "retreat from an unbridled and potentially harmful insistence on rigorous sodium restriction in those with symptomatic heart failure. To state that we can do better is an understatement; to acknowledge our embarrassment for acting upon uncertain logic is closer to the truth."

New data are on the way with the Study of Dietary Intervention Under 100 MMOL in Heart Failure (SODIUM-HF), which is now in progress.

"This is a good step forward but not enough," Yancy writes. "Further trials studying the DASH [Dietary Approaches to Stop Hypertension] diet and other candidate diets in heart failure should be performed. Before we persist with unyielding recommendations for aggressive sodium restriction at significant costs for uncertain benefits and unknown harm, do the trials," he concludes.

Funding for the study was provided by the National Health Service National Institute of Health Research School for Primary Care Research. The study authors and Yancy have disclosed no relevant conflicts of interest.

JAMA Intern Med. Published online November 5, 2018. Article, Editorial

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