This study is a randomized controlled trial designed to evaluate the effects of high-calorie diets and specialized nutritional formulas on weight gain and clinical outcomes in underweight children aged 1 to 5 years with congenital heart disease (CHD). Children with CHD often experience growth failure due to increased energy needs and feeding difficulties, which can negatively impact their recovery, development, and overall health.

Seventy-five children will be randomly assigned to one of three groups: a control group receiving a standard diet, a group receiving a high-calorie diet made from energy-dense foods, and a third group receiving both the high-calorie diet and a specialized high-calorie pediatric formula. The study will measure changes in weight, appetite, feeding tolerance, and other growth indicators over an 8-week period. The goal is to determine whether enhanced nutritional support can improve weight gain and health outcomes in this high-risk population.

Children with congenital heart disease (CHD) are at high risk of growth failure and malnutrition due to a combination of increased metabolic demands and feeding difficulties. Despite advancements in surgical and medical management, undernutrition remains a persistent challenge and can negatively affect recovery, development, and long-term health outcomes. While most nutritional intervention studies focus on infants or the immediate postoperative period, older children with CHD-particularly those aged 1 to 5 years-remain an understudied group, despite ongoing nutritional risks.

This study addresses a critical gap in pediatric cardiac care by evaluating whether targeted nutritional strategies, such as high-calorie diets and specialized pediatric formulas, can support better weight gain and overall health in this population. The intervention is designed to be practical and feasible, combining enriched natural foods and commercially available high-calorie formulas tailored to children with increased energy needs.

By comparing standard care with enhanced nutritional interventions over an 8-week period, this randomized controlled trial aims to provide evidence on effective, non-invasive nutritional approaches for improving the health and development of underweight children with CHD. The results are expected to inform clinical nutrition guidelines and support individualized care plans for pediatric cardiology patients.

Inclusion Criteria:

• Children aged 1 to 5 years.
• Diagnosed with congenital heart disease (confirmed by echocardiography).
• Underweight (weight-for-age below the 10th percentile).
• Medically stable and eligible for oral or enteral feeding.
• Informed consent obtained from a parent.

Exclusion Criteria:

• Children with genetic syndromes known to affect growth (e.g., Down syndrome).
• Children with gastrointestinal conditions impairing nutrient absorption.
• Children who had cardiac surgery within the last 4 weeks.
• Presence of severe organ failure (renal, hepatic, etc.).
• Children on parenteral nutrition.
• Families unlikely to adhere to follow-up or dietary instructions.

Currently, the plan for sharing individual participant data (IPD) is under development. Once finalized, the plan will outline which data elements will be shared, such as de-identified participant-level data, relevant metadata, and supporting documentation. Data sharing will be conducted in accordance with ethical standards and applicable regulations to protect participant confidentiality. Access to the data may be granted to qualified researchers upon reasonable request and subject to data use agreements.

This study is open-label, meaning that both the participants (children and their caregivers) and the researcher are aware of the dietary intervention assigned. Due to the nature of nutritional interventions-different diets and formulas-blinding is not feasible. All outcomes will be assessed objectively to minimize bias.