Deleterious effects of intravenous verapamil in Wolff-Parkinson-White patients and atrial fibrillation.

Three patients presented to the emergency room with atrial fibrillation and fast ventricular response with wide preexcited QRS complexes (Wolff-Parkinson-White syndrome). All three patients received intravenous verapamil (5-10 mg). The first patient developed ventricular fibrillation requiring several defibrillations; the second patient developed severe hemodynamic deterioration requiring urgent cardioversion; in the third patient a marked increment in the ventricular response was noted, however, there was no hemodynamic impairment. Verapamil may cause detrimental results when given to patients with the Wolff-Parkinson-White syndrome and atrial fibrillation. Its administration should therefore be considered as an absolute contraindication in these patients.