Phenytoin as an effective treatment for polymorphic ventricular tachycardia due to QT prolongation in a patient with multiple drug intolerances.

We present a case of a 69-year-old woman presenting with polymorphic ventricular tachycardia caused by QT prolongation. Owing to known intolerances to a majority of antiarrhythmic medications, one remaining option was to initiate phenytoin. Phenytoin's narrow therapeutic window, multiple drug interactions and side effect profile make it an infrequently used antiarrhythmic. It is, however, a potent antiarrhythmic agent, which may be useful in treatment of ventricular tachycardia, especially in patients with multiple drug intolerances. 2015 BMJ Publishing Group Ltd.