Final answer:
In the first 24 hours after a myocardial infarction, a nurse should monitor the patient for the complication of ventricular fibrillation.
Step-by-step explanation:
In the first 24 hours after a myocardial infarction (heart attack), a nurse should monitor the patient for the complication of ventricular fibrillation. Ventricular fibrillation is a life-threatening condition where the ventricles of the heart quiver instead of pumping blood effectively. If left untreated, ventricular fibrillation can lead to brain death. Therefore, it is important for the nurse to closely monitor the patient's cardiac rhythm and be prepared to provide defibrillation if necessary.