## **Core Concept**
Cardioselective β-blockers are a class of β-blockers that primarily affect the heart, reducing heart rate and myocardial contractility. They are selective for β1-adrenergic receptors, which are predominantly found in the heart. This selectivity helps in reducing the risk of bronchospasm and peripheral vasoconstriction associated with non-selective β-blockers.

## **Why the Correct Answer is Right**
Metoprolol is a β1-selective (cardioselective) β-blocker. It primarily blocks β1 receptors in the heart, which results in decreased heart rate, reduced contractility, and lower blood pressure. This cardioselectivity makes metoprolol a preferred option for patients with asthma or chronic obstructive pulmonary disease (COPD), as it has less effect on β2 receptors in the lungs.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Propranolol is a non-selective β-blocker, blocking both β1 and β2 receptors. This lack of selectivity makes it less suitable for patients with respiratory conditions.
- **Option B:** Nadolol is also a non-selective β-blocker but has a longer duration of action compared to propranolol. It does not offer cardioselectivity.
- **Option D:** Pindolol is a non-selective β-blocker with intrinsic sympathomimetic activity (ISA). It does not have cardioselectivity and affects both β1 and β2 receptors.

## **Clinical Pearl / High-Yield Fact**
A key clinical point to remember is that while cardioselective β-blockers like metoprolol are safer in patients with asthma or COPD, they are not completely devoid of risks. High doses can still induce bronchospasm, and their use should be cautious in susceptible patients.

## **Correct Answer:** C. Metoprolol