The management of broad complex atrial fibrillation is complex and may be a source of morbidity and mortality if not correctly recognized and treated appropriately. We present a case series of 3 patients who were managed in our emergency department after complaints of palpitations. They presented with varying forms of rapid atrial fibrillation that had broad complexes on the 12-lead electrocardiogram. The first 2 patients were treated with calcium channel blockers for rate control, and treatment was complicated by rapid arrhythmia that required cardioversion. The final patient was correctly treated with intravenous procainamide. The diagnosis of Wolff-Parkinson-White syndrome was eventually made in all these patients. Broad complex atrial fibrillation must be treated with respect. Cases with rapid ventricular rate can decompensate from mismanagement due to poor ability to recognize the possibility of Wolff-Parkinson-White syndrome in such patients. Procainamide forms the cornerstone of treatment in hemodynamically stable rapid broad complex atrial fibrillation of unknown origin.