From the Guidelines

A low-sodium diet with moderate protein restriction is recommended for Congestive Heart Failure (CHF) patients with Impaired Renal Function.

The goal is to manage fluid status and reduce the strain on the kidneys and heart.
A low-sodium diet is crucial in managing fluid retention, as recommended by the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines 1.
Moderate protein restriction may be beneficial in reducing the generation of nitrogenous wastes and slowing the progression of renal failure, as suggested by the National Kidney Foundation's clinical practice guidelines 1.

Sodium intake: Moderate restriction, as excessive sodium can exacerbate fluid retention.
Protein intake: 0.60-0.75 g protein/kg/d, with at least 50% of high biologic value, to maintain nutritional status while minimizing the strain on the kidneys.
Energy intake: Adequate to maintain nutritional status, with a target of 35 kcal/kg/d.
Fluid management: Careful monitoring and management of fluid status, with diuretic therapy as needed, to prevent volume overload and reduce the risk of renal dysfunction.

Close monitoring of renal function, electrolyte levels, and fluid status is essential in CHF patients with impaired renal function.
A multidisciplinary approach, involving healthcare providers, dietitians, and patients, is necessary to ensure effective management of CHF and impaired renal function.

From the Research

There is limited information on the role of diet in the management of heart failure (HF) with impaired renal function, but some studies suggest that dietary manipulation can improve cardiac performance and delay the progression of the disease 2.
A well-balanced caloric diet represents an effective therapy in overweight HF patients to reduce the mortality rate, and changes in the dietary pattern can reduce the evolution of HF 3.
The Mediterranean diet (MedDiet) has shown beneficial effects on cardiac function in some studies, but the results are conflicting 3.
Nutritional supplements and hypercaloric intake have positive effects on underweight HF patients, while hypocaloric diet is beneficial in obese HF patients improving glucose control and cardiac function 3.
The discriminant factor to prescribe a diet regime in HF patients is represented by body mass index (BMI) 3.

Malnutrition is common in patients with HF, especially at the severe stage of HF, and is associated with the risk of complications and mortality 4.
Evaluation of malnutrition in patients with HF, monitoring of patients in this regard, and identifying the right assessment tools are the basis for developing an effective nutritional strategy 4.
Sodium restriction, obesity, malnutrition, dietary patterns, and specific macronutrient and micronutrient supplementation have been studied in HF patients, but the resulting evidence of benefit is conflicting 5.

Nutrition disorders are often missed in patients with HF due to the lack of standardized definitions and assessment tools to quantify nutritional status 5.
A wide range of dietary interventions and overall dietary patterns have been studied in HF patients, but the evidence of benefit is conflicting 5.
Multimodal nutrition interventions may be beneficial, but the feasibility and challenges associated with implementation need to be addressed 5.