Antibiotic prophylaxis in congenital cardiac disease has long been a topic of debate. Although there is little dispute around antibiotic cover for surgical procedures and catheter interventions where foreign material is being inserted, there are little data specific to non-device-placement procedures such as atrial septostomy or balloon valvotomy. We sought to assess the effect of routine prophylaxis on post-interventional infections via a retrospective pseudo-randomised analysis, and an online survey on paediatric interventional cardiologists in the United Kingdom and United States.