Recurrent Torsades de Pointes Precipitated by Berberine Supplement

Acquired long QT syndrome and torsades de pointes (TdP) can be triggered by dietary supplements, which do not go through strict safety testing.

A 61-year-old man had syncope and recurrent TdP (QTc 669 ms), with an initial electrocardiogram phenotype indistinguishable from congenital LQT2. He was taking several over-the-counter supplements including berberine, dihydroberberine, turmeric, and quercetin and had mild hypomagnesemia. Genetic testing for congenital long QT syndrome was negative. Management included defibrillation, intravenous magnesium, supplement discontinuation, nadolol, and a wearable cardioverter-defibrillator. The QT interval normalized, and nadolol was later discontinued without arrhythmia recurrence.

This case illustrates a "multihit" model, in which supplement-mediated cardiac channel blockade, drug interactions increasing supplement exposure, and hypomagnesemia converged to provoke life-threatening arrhythmia.

Common supplements like berberine can cause TdP through multiple proarrhythmic mechanisms. Thorough evaluation for extrinsic triggers is essential, even when the electrocardiographic phenotype suggests a genetic disorder.