Salt and Fluid in Patients With Chronic Heart Failure
Abstract and Introduction
Aims European and American guidelines have recommended salt and fluid restriction for patients with chronic heart failure (CHF) despite scarce scientific evidence. Therefore, we investigated the effects of salt and fluid restriction in patients with CHF.
Methods and results Ninety-seven stable patients in NYHA class II–IV, on optimal medication, with previous signs of fluid retention, treated with either >40 mg (NYHA III–IV) or >80 mg (NYHA II–IV) of furosemide daily were randomized to either individualized salt and fluid restriction or information given by the nurse-led heart failure clinics, e.g. be aware not to drink too much and use salt with caution, and followed for 12 weeks. Fluid was restricted to 1.5 L and salt to 5 g daily, and individualized dietary advice and support was given. The 24 h dietary recall procedure, urine collection on three consecutive days, and para-aminobenzoic acid 80 mg t.i.d. was used to assess adherence to diet and completeness of urine collection. The primary endpoint was a composite variable consisting of NYHA class, hospitalization, weight, peripheral oedema, quality of life (QoL), thirst, and diuretics.
Results After 12 weeks, significantly more patients in the intervention than in the control group improved on the composite endpoint (51% vs. 16%; P < 0.001), mostly owing to improved NYHA class and leg oedema. No negative effects were seen on thirst, appetite, or QoL.
Conclusion Individualized salt and fluid restriction can improve signs and symptoms of CHF with no negative effects on thirst, appetite, or QoL in patients with moderate to severe CHF and previous signs of fluid retention.
European and American guidelines for the non-pharmacological treatment of patients with chronic heart failure (CHF) recommend dietary salt and fluid restriction, especially in moderately to severely symptomatic patients; however, this recommendation lacks convincing scientific documentation and evidence. In the 2012 guidelines from the European Society of Cardiology (ESC), the recommendations have been changed to 'avoid excessive fluid intake' and 'weight-based fluid restriction may cause less thirst', and salt restriction is listed in 'Gaps in evidence'. Salt and fluid restriction has been shown to decrease urinary sodium excretion and extracellular water; however, the study sample comprised asymptomatic or mildly symptomatic patients. Another study found that patients receiving high doses of furosemide, fluid intake restricted to 1 L day, and a sodium restriction of 80 mmol/day had a worse outcome than those on 120 mmol/day. In a meta-analysis of six randomized trials of low vs. normal sodium diet including 2747 patients, a low sodium diet increased all-cause mortality. However, all studies in the meta-analysis came from the same research group who had used a very similar approach in all studies (high doses of diuretics and 1 L fluid daily in addition to salt reduction). In stable patients with moderate CHF, favourable effects on thirst and adherence to a liberal fluid restriction based on body weight have been reported. Salt and fluid restrictions interfere with the patients' eating habits and quality of life (QoL), which in turn may impact negatively on adherence. Patients also relate their thirst to the loss of body water caused by diuretics (even if tolvaptan is the only drug reported to increase thirst). Eating habits may also change with age, with a higher use of ready meals. In addition, salt restrictions may result in loss of appetite as food loses its appeal and taste, and fluid restrictions may cause an increase in thirst. Consequently, there is a need to know if salt and fluid restriction improves functional ability and reduces hospitalizations without concomitant negative impacts on QoL.
In a previous pilot study, we found that patients with moderate to severe CHF were able to reduce their sodium and fluid intake without any negative effects on thirst, appetite, and QoL. Therefore, we wanted to evaluate the effect of salt and fluid restriction on a composite endpoint, consisting of NYHA class, hospitalization, body weight, peripheral oedema, QoL, thirst, and diuretics, in a powered study to obtain solid evidence for recommendations for its use in CHF patients.