Beyond the Aorta: Incidental Atrial Septal Defect in a Patient With Marfan Syndrome and Severe Aortic Dilation

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder caused by mutations in the FBN1 gene, which carries a high risk of cardiovascular morbidity and mortality. We present the case of a 31-year-old man with a severe Marfanoid phenotype who was admitted with decompensated heart failure, septic shock, and renal failure. After stabilization, multimodal evaluation revealed a severely dilated aortic root and severe aortic regurgitation, along with an incidental 11 mm ostium secundum atrial septal defect (ASD). This unusual combination caused critical biventricular overload. The patient underwent a successful Bentall-Bono procedure and closure of the ASD. This case underscores the importance of a thorough physical examination and comprehensive diagnosis for successful surgery in patients with complex connective tissue disorders.