Fatal ventricular fibrillation following verapamil in Wolff-Parkinson-White syndrome with atrial fibrillation.

A 29-year-old man with Wolff-Parkinson-White syndrome and atrial fibrillation developed fatal ventricular fibrillation shortly after receiving intravenous verapamil. The patient presented with an irregular pulse of 190. A total of 23 mg of verapamil was administered in small intravenous doses over 35 minutes. The ventricular rate accelerated as verapamil was administered, and fatal ventricular fibrillation followed. Three theoretical mechanisms by which verapamil may enhance conduction of atrial fibrillation in Wolff-Parkinson-White syndrome, predisposing to ventricular fibrillation, are mentioned.