Which antiarrhythmic should be avoided as first-line therapy for atrial fibrillation unless the patient has heart failure or substantial LVH?

• A. Dronedarone
• B. Digoxin
• C. Amiodarone
• D. Sotalol

Answer: (C)

In older adults, antiarrhythmics can carry substantial toxicity and proarrhythmic risks, so the Beers criteria generally avoids using them as first-line for atrial fibrillation unless there is a specific structural heart issue such as heart failure or marked left ventricular hypertrophy. Amiodarone stands out here because, despite its long-term toxicity concerns, it has the most favorable safety profile for rhythm control in patients with heart failure or LVH compared with other antiarrhythmics. Other options either worsen heart failure, have high proarrhythmic risk in structural disease, or are mainly useful for rate control rather than rhythm control. Dronedarone is contraindicated in heart failure and LV dysfunction; digoxin is primarily for rate control; sotalol and dofetilide require careful monitoring for proarrhythmia; flecainide and propafenone are discouraged in structural heart disease. So amiodarone is the preferred choice only when heart failure or substantial LVH is present, making it the best answer to this scenario.