Which medication can be used for rapid control of atrial fibrillation in a patient with narrow QRS complex?

Rapid control of atrial fibrillation, particularly in patients exhibiting a narrow QRS complex, is best achieved using a calcium channel blocker like Cardizem (diltiazem). This medication works by slowing down conduction through the atrioventricular (AV) node and reducing the heart rate, which is particularly effective in the context of atrial fibrillation. The rapid onset of action and ability to administer it intravenously allows for immediate heart rate control, making it a preferred choice in acute situations.

Digoxin, while it can be used to help control the heart rate, generally has a slower onset compared to Cardizem and is more suited for chronic management. It is also not typically the first line for urgent control in an acute setting. Amiodarone is an antiarrhythmic that can be effective in various arrhythmias, including atrial fibrillation, but it is usually utilized for rhythm control rather than immediate rate control. Lidocaine is primarily indicated for ventricular arrhythmias and is not appropriate for the management of atrial fibrillation, particularly given the narrow QRS complex setting. Thus, Cardizem stands out as the ideal choice for rapid control in this scenario.