Which medication is primarily used to treat heart failure due to poor contractility?

Digoxin is primarily used to treat heart failure due to poor contractility. It belongs to a class of medications known as cardiac glycosides, which work by increasing the force of heart contractions (positive inotropic effect). This enhances the heart's ability to pump blood effectively, thereby improving symptoms and functional status in patients with heart failure. Additionally, digoxin helps to regulate heart rate by inhibiting the sodium-potassium ATPase pump, which can be particularly beneficial for patients who also have atrial fibrillation.

While other medications listed have important roles in managing heart conditions, they do not primarily target poor contractility in heart failure. Aspirin is an anti-inflammatory and antiplatelet drug, commonly used for preventing blood clots. Furosemide is a loop diuretic that helps to reduce fluid overload, which can alleviate symptoms of heart failure but does not directly improve contractility. Metoprolol is a beta-blocker that can improve heart function over time, but its primary role is to manage heart rate and blood pressure rather than directly enhancing contraction strength.

Thus, digoxin stands out as the medication specifically aimed at improving heart muscle contraction in cases of heart failure, making it the correct choice.