Answer:
Decreased heart rate
Quinidine, a Class IA antidysrhythmic drug, slows the conduction rate and prolongs repolarization, which decreases heart rate such as in atrial fibrillation with a rapid ventricular response. Decreasing heart rate is a therapeutic effect. However, the nurse will need to monitor for a heart rate of less than 60 beats/minute, indicating bradycardia, which is a side effect of quinidine.