Although the arrhythmia persisted, no further ICD shocks were observed. The patient remained asymptomatic. Electrolyte analysis demonstrated a serum potassium level of 3.1 mEq/L (to convert to millimoles per liter, multiply by 1.0) and a magnesium level of 1.97 mEq/L (to convert to millimoles per liter, multiply by 0.5). Potassium replacement was undertaken. He was transferred to the intensive care unit and conscious sedation was administered. Forty-five minutes after arrhythmia onset, a biphasic 200-J external direct current shock converted the patient back to sinus rhythm. Diuresis was continued, and the patient was discharged from the hospital 1 week later without further arrhythmic complication.