**Core Concept**
Atrial fibrillation and atrial flutter are types of supraventricular tachyarrhythmias characterized by rapid and irregular heart rhythms originating from the atria. The management of these conditions often involves the use of antiarrhythmic medications to restore and maintain a normal sinus rhythm.

**Why the Correct Answer is Right**
The correct answer is **Dofetilide**. Dofetilide is a class III antiarrhythmic medication that works by inhibiting the rapid component of the delayed rectifier potassium channel (IKr). This action prolongs the action potential duration and refractory period in the atria, thereby reducing the rate of atrial fibrillation and atrial flutter. Dofetilide is particularly effective in converting atrial fibrillation to sinus rhythm and maintaining sinus rhythm in patients with atrial fibrillation.

**Why Each Wrong Option is Incorrect**
**Option A:** Amiodarone is a class III antiarrhythmic medication, but it is not the first-line treatment for atrial fibrillation and atrial flutter due to its potential for side effects and interactions.

**Option B:** Digoxin is a cardiac glycoside that can be used to control ventricular rate in patients with atrial fibrillation, but it does not have a significant effect on converting atrial fibrillation to sinus rhythm.

**Option C:** Metoprolol is a beta-blocker that can be used to control ventricular rate in patients with atrial fibrillation, but it does not have a significant effect on converting atrial fibrillation to sinus rhythm.

**Clinical Pearl / High-Yield Fact**
Dofetilide is a useful medication for patients with atrial fibrillation and atrial flutter, but it requires careful monitoring of the QT interval due to its potential to prolong it.

**Correct Answer:** D. Dofetilide