A man in his 50s arrived at a fast-food restaurant feeling dizzy and experiencing shortness of breath. Emergency medical services were called. On their arrival, the patient was found conscious but diaphoretic with a blood pressure of 96/67 mm Hg and a heart rate of 190 bpm. His initial electrocardiogram (ECG) showed a fast, regular, wide QRS complex tachycardia (WQRST) (Figure 1). Intravenous lidocaine was given without effect; consequently, electrical cardioversion was pursued. An initial synchronized shock of 100 J was delivered; however, this did not terminate the tachycardia. Instead, the rhythm deteriorated into ventricular fibrillation (VF) (Figure 2). Subsequently, 4 more shocks with escalating energy were delivered but failed to convert him to sinus rhythm. Eventually, a final shock of 360 J was successful to establish normal sinus rhythm with transient AV block, which resolved spontaneously (eFigure 1 in the Supplement).