No Point to 'Aggressive' Sodium, Fluid Restriction Seen in Acute HF

Steve Stiles and Michael O'Riordan

May 21, 2013

PORTO ALEGRE, Brazil and LISBON, Portugal (updated May 28, 2913) — In a rare randomized test of a common management strategy, low-sodium diet and fluid restriction in patients with acute decompensated heart failure (ADHF), the intervention had no effect on weight loss or clinical stability over three days compared with "liberal fluid and sodium intakes"[1].

Moreover, "this aggressive intervention was associated with significantly higher rates of perceived thirst," observe the authors, led by Dr Graziella Badin Aliti (Hospital de Clínicas de Porto Alegre, Brazil). "In view of the importance of this sensation in patients already experiencing discomfort with the symptoms of HF, this is a matter of concern" and, they write, "adds a negative component to an intervention that, thus far, had appeared neutral in terms of weight loss and relief of clinical congestion."

In the trial that randomized only 75 patients, there was no effect from sodium and fluid restriction on rate of rehospitalization at 30 days, report Aliti et al May 20, 2013 in JAMA Internal Medicine.

In an accompanying editorial[2], Dr Melvin D Cheitlin (University of California, San Francisco) contends that the trial's "small numbers of participants make the conclusion of similar readmission rates at 30 days somewhat tentative." Nonetheless, he writes, the study in the context of others in the literature "confirm that, in patients admitted with ADHF, fluid and salt restriction, at least to the extent present in these studies, is not necessary during hospitalization."

Expert Opinion vs Clinical Data

The study, which was presented this week at Heart Failure Congress 2013 , a meeting of the European Society of Cardiology Heart Failure Association, was an attempt to address a clinical issue that lacks randomized controlled clinical data to support expert opinion, according to senior investigator Dr Luis Beck da Silva (Federal University of Rio Grande do Sul, Porto Alegre, Brazil).

To heartwire , da Silva said there are just two randomized controlled clinical trials comparing a fluid-restricted diet vs normal fluid consumption, but the differences in the amount of fluids consumed between the treatment arms and the comparator arms were too small, just 400 mL/day, to have much of an impact on heart-failure outcomes.

"The idea in this trial was to make the difference in sodium and fluid intake wider than previous studies have made," said da Silva. "In two previous studies, the results were neutral, so we wanted to address the question sufficiently, and that's why we compared two different strategies, one that was completely liberal, and the other that was severely restricted."

With limited evidence, there is wide disparity in the clinical guidelines when it comes to fluid and sodium intakes for hospitalized patients. For example, the heart-failure practice guidelines recommend limiting sodium to 2.0 to 2.4 g/day, while the Heart Failure Society of America recommends 2.0 to 3.0 g/day (<2.0 g/day for those with moderate or severe heart failure). At his hospital in Brazil, the goal is to restrict sodium intake to approximately 800 mg/day. However, this is all based only on expert opinion (level of evidence C), said da Silva.

Aggressive vs Liberal Salt and Water Intake

The patients with LV systolic dysfunction who had been in the hospital for <36 hours were randomized to fluid and sodium restriction (maximum intakes of 800 mL/day and 800 mg/day, respectively, until the seventh hospital day, n=38) or "a standard hospital diet, with liberal fluid (>2.5 L/day) and sodium (approximately 3–5 g/day) intake" (n=37). The two groups didn't differ at baseline with respect to demographics, clinical features, or current medications, nor did their hospitalization times differ significantly.

From baseline to day three, the two groups showed no significant differences in:

  • Mean weight loss, a surrogate for fluid loss (4.42 kg in the intervention group vs 4.67 kg for controls, p=0.82).

  • Improvement in clinically overt congestion (p=0.47) as indicated by clinical congestion scores, an index based on symptoms and signs of congestion.

  • · Administration of IV diuretics, vasodilators, or inotropic agents for heart-failure management.

  • Time to transition from IV to oral diuretics.

On the other hand, perceived thirst as measured on a visual analog scale, similar at baseline, was significantly worse in the fluid/sodium-restriction group (p=0.01).

The 30-day readmission rates were 29% for fluid/sodium-restricted patients and 19% for controls (p=0.41). At this point, however, patients in the intervention group showed significantly higher clinical congestion scores (p=0.002).

As an explanation for latter finding, Cheitlin proposes that "since the diet of patients in the intervention group was no longer restricted to a low amount of salt or fluid after discharge, their hunger and thirst may have led to greater salt and water intake."

To heartwire , da Silva said the results are clear and show that an aggressive strategy to limit sodium and fluids has no impact on clinical stability and weight loss. As such, a strategy designed to limit fluids and sodium is "unnecessary" in patients with acute decompensated heart failure. He said that the concept of limiting sodium and fluids emerged many years ago, and pharmacological treatment of decompensated heart failure patients has changed dramatically.

Discussing the results during the late-breaking clinical-trials session, Dr Theresa McDonagh (King's College, London, UK) said the role of dogma has gone a long way toward maintaining aggressive sodium and fluid restrictions in patients with heart failure, especially given the lack of randomized clinical trial data. Although the study is small and the intervention arm rather aggressive, the study helps address an unmet need in clinical practice.

"The study took a long time to recruit, just over three years, and I think that reflects that these type of lifestyle intervention studies are difficult to do given the lack of evidence that we have," said McDonagh.

Cheitlin, da Silva, McDonagh, and Aliti et al no had conflict-of-interest disclosures.


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