Simultaneous transcatheter management of incidental critical left main coronary artery disease in a young woman undergoing atrial septal defect device closure.

Transcatheter device closure is the preferred treatment for secundum atrial septal defect (ASD) in young adults with suitable anatomy. In this population, routine coronary angiography is generally not recommended in the absence of ischemic symptoms or conventional cardiovascular risk factors. However, coronary imaging is selectively performed during ASD intervention to delineate anomalous coronary anatomy at risk of device-related compression, and emerging evidence indicates that clinically significant coronary artery disease may occasionally coexist silently in younger adults. We report the case of a 28-year-old asymptomatic woman undergoing transcatheter closure of a large secundum ASD with deficient rims, in whom coronary angiography performed during invasive catheterization unexpectedly revealed critical left main coronary artery stenosis. Intravascular ultrasound (IVUS) confirmed severe luminal compromise, and successful IVUS-guided left main coronary stenting was performed, followed by device-assisted ASD closure in the same procedural session. Retrospective clinical assessment revealed a history of premature sudden cardiac death in a first-degree relative. This case illustrates the potential for occult yet prognostically significant coronary artery disease in young adults undergoing congenital heart interventions and supports a selective, individualized, and context-driven approach to coronary evaluation, consistent with contemporary adult congenital heart disease guidelines.