Cor triatriatum is a rare, congenital heart defect. When diagnosis does not occur in infancy, primary symptoms in an older patient may mimic reactive airway disease. We report a case of cor triatriatum in an older child, previously diagnosed with asthma, presenting to an emergency department with a chief complaint of wheezing. Initial treatment with bronchodilators and corticosteroids was unsuccessful, prompting thorough evaluation. Subsequent imaging diagnosed cor triatriatum sinister. When presentations consistent with common conditions, such as asthma, do not respond appropriately to classic intervention, emergency physicians must be prepared to consider alternative and rare diagnoses.
