Atrial Flutter Secondary to Severe Laxative-Induced Hypomagnesemia in Anorexia Nervosa: A Case Report.

Atrial flutter is an uncommon supraventricular arrhythmia in young adults without structural heart disease and is typically associated with underlying cardiac pathology rather than isolated metabolic abnormalities. Electrolyte disturbances, particularly hypomagnesemia, can contribute to myocardial electrical instability, but they rarely present as the primary cause of atrial flutter in otherwise healthy young individuals. We present the case of a 23-year-old woman with a history of anorexia nervosa and generalized anxiety disorder who presented with acute palpitations, dizziness, and near-syncope. An electrocardiogram (ECG) was performed and demonstrated typical atrial flutter with a 4:1 atrioventricular conduction pattern in the setting of profound hypomagnesemia secondary to chronic stimulant laxative abuse. Laboratory studies also revealed mild hypokalemia and metabolic alkalosis consistent with ongoing gastrointestinal losses and severe nutritional restriction. She was treated with intravenous (IV) magnesium sulfate and potassium replacement without the use of antiarrhythmic medications, rate-control agents, or electrical cardioversion. Following correction of her electrolyte abnormalities, she spontaneously converted to normal sinus rhythm within several hours, with complete resolution of symptoms and no recurrence during her hospital stay. This case highlights how severe hypomagnesemia may have been a significant contributing factor to atrial flutter in a young patient without structural heart disease. It also emphasizes the importance of promptly identifying and correcting electrolyte abnormalities in patients with eating disorders and laxative abuse, as early treatment can rapidly reverse potentially serious but reversible cardiac manifestations and avoid unnecessary invasive management.