## **Core Concept**
Cardioselective beta blockers are a class of beta blockers that primarily affect the heart, blocking β1-adrenergic receptors. This selectivity allows them to reduce heart rate and contractility with less effect on airway resistance and peripheral circulation. They are preferred in patients with asthma or chronic obstructive pulmonary disease (COPD).

## **Why the Correct Answer is Right**
Propranolol is a non-selective beta blocker, meaning it blocks both β1 and β2-adrenergic receptors. This non-selectivity affects not only the heart but also the lungs, liver, and peripheral circulation. Therefore, it does not spare the β2 receptors found in the bronchial smooth muscle, making it less ideal for patients with respiratory conditions.

## **Why Each Wrong Option is Incorrect**
* **Option A:** Atenolol is a cardioselective beta blocker, primarily affecting β1 receptors in the heart.
* **Option B:** Metoprolol is also cardioselective, mainly blocking β1 receptors.
* **Option D:** Bisoprolol is another cardioselective beta blocker with high β1 selectivity.

## **Clinical Pearl / High-Yield Fact**
A key clinical point to remember is that while cardioselective beta blockers are safer for patients with asthma or COPD, they are not completely without risk. High doses can lose selectivity, and patients with asthma or COPD should still be monitored closely.

## **Correct Answer:** . Propranolol