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Safety, efficacy of sodium restriction in patients with HF questioned in new study
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Sodium restriction may increase the risk for death or HF hospitalization in symptomatic patients with HF, according to new data from the HART trial.
Although current guidelines advise sodium restriction for patients with HF, data on the effect on HF outcomes are inconsistent. To further assess the effect of sodium restriction in this population, Rami Doukky, MD, MSc, professor of medicine, preventive medicine and radiology and chief of the division of cardiology at John H. Stroger, Jr. Hospital of Cook County, Chicago, and colleagues utilized data from the HART trial.
Rami Doukky
Sodium intake data were available for 833 (145 sodium restricted, 688 sodium unrestricted) of the 902 NYHA class II/III HF patients enrolled in the trial. Of these 833 patients, 260 were propensity matched into sodium-restricted (< 2,500 mg/day; n = 130) and sodium-unrestricted (2,500 mg/day; n = 130) groups.
The primary outcome measured was a composite of death or HF hospitalization. Secondary outcomes included cardiac death and HF hospitalization. Median follow-up was 36 months (interquartile range, 27-36).
Impact on outcomes
In the propensity-matched cohort overall, 89 events of death or HF hospitalization (adjusted HR = 1.72; 95% CI, 1.12-2.65) were reported, according to Doukky and colleagues. Sodium restriction was associated with a 42.3% risk for death or HF hospitalization compared with a 26.2% risk for the sodium-unrestricted group (adjusted HR = 1.72; 95% CI, 1.12-2.65). The rate of HF hospitalization was 32.3% in the sodium-restricted group vs. 20% in the unrestricted group (adjusted HR = 1.68; 95% CI, 1.02-2.75). According to subgroup analyses, sodium restriction was associated with increased risk for death or HF hospitalization in patients not assigned ACE inhibitors or angiotensin receptor blockers (HR = 5.78; 95% CI, 1.93-17.27).
“Our findings support further downgrade of the [American College of Cardiology Foundation and the American Heart Association] sodium-restriction recommendation in patients with chronic HF to class IIb (efficacy less well-established, conflictive evidence) and press the need for multicenter randomized trial to definitively address the role of sodium restriction in HF management,” Doukky and colleagues wrote.
Because of its observational design, this study could not determine causality, Doukky told Cardiology Today. Another limitation of the trial was self-reported estimation of sodium.
“However, we could conceivably speculate on causality based on basic pathophysiology of congestive HF,” Doukky said. “Sodium restriction may cause intravascular volume contraction. As a result, this volume contraction may lead to stimulation of the RAAS system and the sympathetic activity in the body, and consequent fluid retention.”
Doukky emphasized that this study “is not about sodium binging, nor [did the researchers address] people in acute HF who have already presented to the hospital with fluid overload. In patients hospitalized with acute decompensated HF, sodium restriction makes sense because we want to get rid of the excess fluid. This is not what our study is about, however; it is about chronic daily salt consumption in patients with chronic compensated HF.”
Future investigation
In a related editorial, Scott L. Hummel, MD, MS, and Matthew C. Konerman, MD, of the University of Michigan and the Ann Arbor Veterans Affairs Health System, wrote: “We agree with the conclusion of Doukky et al that randomized trials evaluating sodium restriction in patients with HF receiving standard of care treatment are sorely needed. Until then, a recent [AHA] Science Advisory provides a framework by which observational studies relating sodium intake to [CV] outcomes can be analyzed.”
Hummel and Konerman said future studies should address errors and misclassification in sodium intake, as well as measure other confounders such as overall nutritional status and previous hospitalization.
Clyde W. Yancy, MD, MSc , of Northwestern University Feinberg School of Medicine, commented in another editorial that although Doukky and colleagues call for a closer look at the effect sodium restriction has on HF outcomes, it does not provide any definitive answers.
“The patients studied in the HART database and reported by Doukky et al do not reflect the contemporary era of HF therapy and, despite very careful propensity matching, it remains likely that sodium restriction as shown in the present data serves more as a marker for advanced disease. Certainly, there are no data to infer causality,” Yancy wrote. – by Tracey Romero
Disclosure: Doukky reports research funding from Astellas Pharma. Yancy and Konerman report no relevant financial disclosures. Hummel reports research funding from PurFoods, LLC, as well as from NIH grants.
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