Which drug may be used to convert new-onset atrial fibrillation?

• A. Metoprolol
• B. Digoxin
• C. Amiodarone
• D. Adenosine

Answer: (C)

Converting new-onset atrial fibrillation to normal rhythm relies on using an antiarrhythmic that can terminate the fibrillation and restore sinus rhythm. Amiodarone fits this role well because it has broad antiarrhythmic activity (Class III effects with some Class I–IV actions) and can be effective across a range of patients, including those with structural heart disease or heart failure. When given intravenously, it can terminate atrial fibrillation and bring back a stable rhythm, making it a practical choice for chemical cardioversion in the emergency setting.

In contrast, a beta-blocker like metoprolol is primarily used to slow the ventricular rate during AF and does not reliably convert the rhythm. Digoxin also mainly provides rate control and has limited effectiveness for acute conversion. Adenosine, while useful for diagnosing or treating certain narrow complex tachycardias by transiently blocking AV nodal conduction, does not convert atrial fibrillation to sinus rhythm and is not a reliable agent for rhythm restoration.