A 72-year-old woman with a 15-year history of essential hypertension and chronic obstructive pulmonary disease (COPD) presents with palpitations and an irregular pulse. Her heart rate is 110 bpm and blood pressure is 165/98 mmHg. ECG confirms atrial fibrillation with a rapid ventricular response. She is not in acute heart failure. Current medications include inhaled salbutamol and ipratropium. Which beta blocker would be most appropriate for rate control in this patient?

Explanation

## Clinical Scenario Analysis This patient presents with: - Atrial fibrillation with rapid ventricular response (110 bpm) - Need for rate control and blood pressure reduction - **Critical contraindication: COPD** (absolute contraindication to non-selective beta blockers) ## Why Bisoprolol Is the Correct Choice **Key Point:** Bisoprolol is a **highly selective β1-blocker** with the highest cardioselectivity among available beta blockers, making it the safest option in COPD. ### Mechanism of Selectivity **Mnemonic for β1-selective agents: "BEAM"** - **B**isoprolol - **E**smolol - **A**tenolol - **M**etoprolol Bisoprolol has the **highest β1-selectivity ratio** (>300:1 for β1:β2), meaning: 1. Minimal β2-receptor blockade at therapeutic doses 2. Preserved bronchodilation via β2-agonists (salbutamol) 3. No increase in airway resistance 4. Effective rate control in atrial fibrillation ## Selectivity Comparison of Options | Beta Blocker | Selectivity | β1:β2 Ratio | COPD Safety | AF Rate Control | Notes | |--------------|------------|------------|-------------|-----------------|-------| | **Bisoprolol** | Highly selective | >300:1 | Safest | Excellent | Preferred in COPD | | Metoprolol | Selective | 50:1 | Moderate risk | Good | Less selective than bisoprolol | | Labetalol | Non-selective | α & β mixed | Contraindicated | Fair | Alpha-blockade; still blocks β2 | | Propranolol | Non-selective | 1:1 | **Contraindicated** | Excellent | Risk of bronchospasm | **High-Yield:** In COPD patients requiring beta blockade: - **First choice: Bisoprolol** (highest β1-selectivity) - **Second choice: Metoprolol** (if bisoprolol unavailable) - **Avoid: Propranolol, labetalol, carvedilol** (non-selective or mixed) ## Clinical Pearl Beta-2 receptor blockade causes bronchial smooth muscle constriction and increases airway resistance. Highly selective β1-blockers spare β2 receptors at therapeutic doses, allowing exogenous β2-agonists (salbutamol) to work effectively. Bisoprolol's superior selectivity makes it ideal in COPD. ## Dosing in Atrial Fibrillation Bisoprolol 2.5–10 mg once daily, titrated to achieve resting heart rate 60–80 bpm and blood pressure control.