Digoxin is primarily used to treat which condition?

Digoxin is primarily used to treat heart failure and atrial fibrillation due to its ability to improve the efficiency of the heart and regulate heart rhythm. In heart failure, digoxin acts by increasing the force of myocardial contraction, which enhances cardiac output and can alleviate symptoms. It achieves this effect through inhibition of the sodium-potassium ATPase pump, leading to increased intracellular calcium levels that enhance the heart's contractility.

In the context of atrial fibrillation, digoxin helps to control the ventricular rate by enhancing vagal tone, which slows down conduction through the atrioventricular (AV) node. This is particularly beneficial in patients who have rapid ventricular responses to atrial fibrillation.

The other options do not align with the primary uses of digoxin. While hypertension can be managed with various medications, digoxin is not commonly used as a first-line treatment for high blood pressure. Hyperlipidemia and diabetes are treated with different classes of medications, such as statins for cholesterol levels and insulin or oral hypoglycemics for diabetes, respectively. Thus, the use of digoxin is specifically targeted towards the management of heart failure and atrial fibrillation, making the selected condition correct.