The aim of the present study was to evaluate the effects of a high fat, low carbohydrate (CHO) diet on clinical status during 60 days of follow-up in patients with stable heart failure (HF).

In a randomized controlled clinical trial 44 ambulatory patients with HF were included, assigned to an intervention (40% CHO, 40% fat and 20% protein; n=22) or control groups (50% CHO, 30% fat, 20% protein; n=20). Both groups received recommended pharmacological management. At baseline and at 2 months of follow-up, the variables evaluated were: body composition, handgrip strength, oxygen saturation, dietary intake, clinical data, lipid profile, plasma glucose and exercise tolerance

Nutritional therapy in patients with heart failure (HF) has been focused on fluid and sodium restriction to decrease volume overload. This has proved to decrease extracellular water levels, which manifests as a reduction in edema. Also, in patients with HF and preserved ejection fraction, reduction of sodium in addition to the Dietary Approaches to Stop Hypertension (DASH) diet has been associated with improved left ventricular diastolic function and arterial elasticity, reduced blood pressure, and modestly lower mortality in HF women.

Some studies focused on reducing cardiovascular risk suggest that saturated fatty acids should be replaced by some other macronutrient. Clinical trials which evaluated the replacement of saturated fatty acids with monounsaturated or polyunsaturated fatty acids have found an improvement in blood lipid concentrations and reduced cardiovascular risk in different populations. In the case of omega (n)-3 polyunsaturated fatty acids (PUFA), antiarrhythmic, antithrombotic, anti-atherogenic, and anti-inflammatory effects , improvement of endothelial function, lower blood pressure and plasma triglycerides, and reduced mortality and admission to the hospital for cardiovascular reasons have been documented in patients with chronic heart failure. In addition, the Mediterranean diet, which is high in monounsaturated fatty acids, was associated with cardiovascular risk reduction in other populations.

In HF PUFA was associated with better systolic and diastolic function, but with no effect on mortality. On the other hand, the replacement of saturated fatty acids by carbohydrates must be considered responsible for the possible increase in total cholesterol, LDL cholesterol (LDL-c), plasma triglycerides and decreased HDL cholesterol. Furthermore, the metabolism of carbohydrates induces higher oxygen consumption (VO2), higher carbon dioxide (VCO2) production and increased minute ventilation (VE). In other populations, it has been associated with lower respiratory efficiency and decreased exercise tolerance.

HF should be considered a complex condition in which the heart fails to deliver enough oxygen-rich blood to meet the body's needs, and these patients characteristically have skeletal muscle dysfunction and compromised pulmonary function and ventilatory response, with peak oxygen consumption reduced and deterioration of their clinical state.

Nonetheless, nutritional therapy of HF patients has not been focused on optimizing mechanical ventilation with improved consumption of oxygen. Moreover, studies that examine nutritional therapy in HF have not evaluated the ventilatory response. Therefore, we propose to evaluate the effects of a high fat and low carbohydrate diet on clinical status of chronic stable HF patients.

Inclusion Criteria:

• The diagnosis of heart failure
• New York Heart Association functional classes I to III

Exclusion Criteria:

• New Year Heart Association functional classes IV symptoms
• Patients with severe renal insufficiency (estimated glomerular filtration rate <30 mL/min per 1.73 m2) - Patients with hepatic failure
• Patients with specific dietary regimen