Analysis of 606 pediatric outpatients with congenital heart disease at a major Indonesian hospital revealed that nearly half exhibited underweight or severe underweight nutritional status. Ventricular septal defects were the most common diagnosis, with younger children and those with higher clinical burden showing increased malnutrition risk. This finding illuminates a critical intersection between cardiac health and nutritional status in developing populations. The malnutrition rates observed are substantially higher than typical pediatric populations, suggesting congenital heart disease creates a vicious cycle where cardiac dysfunction impairs growth while poor nutrition further compromises cardiovascular health. For families managing pediatric heart conditions, this underscores the importance of aggressive nutritional monitoring alongside cardiac care. The study's focus on a resource-limited setting provides valuable real-world data often missing from Western research, though the single-center design limits generalizability. As this is a preprint awaiting peer review, these concerning malnutrition rates require confirmation through larger multicenter studies. The research represents important foundational work for pediatric cardiology in Southeast Asia, where congenital heart disease burden is rising but nutritional support resources remain limited.