In atrial fibrillation with heart failure, which agent is preferred for rate control?

• A. Calcium channel blocker
• B. Beta-blocker
• C. Digoxin
• D. Amiodarone

Answer: (C)

In atrial fibrillation with heart failure, the goal is to slow the ventricular rate without worsening cardiac output. Digoxin does this well because it has two helpful actions: it increases vagal tone, which slows AV nodal conduction and reduces the ventricular rate at rest, and it provides a positive inotropic effect by inhibiting the Na+/K+ ATPase, which can improve cardiac output in heart failure. This combination makes digoxin particularly useful when systolic function is reduced.

Calcium channel blockers that slow AV nodal conduction (like diltiazem or verapamil) can depress ventricular contractility and worsen heart failure, so they are not preferred. Beta-blockers do reduce rate and improve outcomes in chronic heart failure, but they can be problematic if heart failure is not well compensated and may not control rate as effectively at rest. Amiodarone can help with rhythm and sometimes rate control, but it carries toxicity risks and isn’t the first-line choice for rate control in this specific scenario.

Therefore, digoxin is the best choice for rate control in atrial fibrillation with heart failure.