Quinidine-induced torsade de pointes suppressed by paroxysmal atrial fibrillation.

A 74-year-old patient is presented in whom quinidine-induced torsade de pointes was abolished by the onset of atrial fibrillation with a fast ventricular response. Heart rate acceleration during atrial fibrillation shortened the Q-T interval from 0.68 on admission to 0.44 milliseconds when sinus rhythm was re-established. This resulted in the suppression of paroxysms of polymorphous ventricular tachycardia.