A 52-year-old man with a history of acute myocardial infarction is brought to the emergency department in cardiac arrest. ACLS protocol has been initiated with chest compressions and bag-mask ventilation. After 2 minutes of high-quality CPR, the monitor shows a coarse ventricular fibrillation (VF). Defibrillation is attempted immediately but the rhythm persists. A second defibrillation attempt is made without success. What is the most appropriate next step in management?