Beta-blockers antagonize beta-adrenergic receptors and reduce sympathetic stimulation of the cardiovascular system.

Primary Effects:

• ↓ Heart rate • ↓ Contractility • ↓ Renin release • ↓ Cardiac output • ↓ Blood pressure

They are used in:

• Hypertension • Heart Failure (HFrEF) • Arrhythmias • Angina • Post-myocardial infarction

Beta receptors:

• β1 – Heart & kidney (↑ HR, ↑ contractility, ↑ renin) • β2 – Bronchi & vascular smooth muscle (bronchodilation)

Beta-blockers reduce:

• Cardiac output • Myocardial oxygen demand • RAAS activation

Block both β1 and β2 receptors.

• Propranolol • Nadolol • Timolol

Characteristics:

• Higher risk of bronchospasm • Avoid in asthma or severe COPD

Primarily block β1 receptors.

• Metoprolol • Atenolol • Bisoprolol • Nebivolol • Acebutolol

Preferred in:

• Reactive airway disease • Diabetes

Note: Selectivity is dose-dependent (lost at higher doses).

Provide additional vasodilation via:

• α1 blockade • Nitric oxide release

Alpha/Beta Blockade:

• Labetalol • Carvedilol

Nitric Oxide–Mediated Vasodilation:

• Nebivolol

Effects:

• ↓ Heart rate • ↓ Contractility • ↓ SVR

Often better tolerated metabolically.

Some beta-blockers partially stimulate β receptors while blocking them.

• Pindolol • Acebutolol

Less commonly used in modern practice.

Evidence-based agents:

• Carvedilol • Metoprolol Succinate • Bisoprolol

→ Heart Failure Module

• Not first-line in uncomplicated HTN • Preferred in CAD, arrhythmia, or HFrEF

→ Hypertension Module

• Rate control in atrial fibrillation • Suppress supraventricular tachycardia

→ Dysrhythmias Module

• Reduce myocardial oxygen demand

→ Anti-Anginal Module

• Bradycardia • AV block • Hypotension • Fatigue • Depression • Erectile dysfunction • Mask hypoglycemia • Bronchospasm (1st generation agents)

• Severe bradycardia • High-grade AV block (without pacemaker) • Cardiogenic shock • Acute decompensated heart failure

Use caution in:

• Asthma • Severe peripheral vascular disease

✔ Only certain agents reduce mortality in HFrEF ✔ 2nd generation agents are β1 selective ✔ 3rd generation agents provide vasodilation ✔ Avoid abrupt discontinuation (rebound tachycardia) ✔ Not first-line for uncomplicated hypertension

Related:

→ Hypertension Module → Heart Failure Module → Dysrhythmias Module → Return to Cardiovascular Modules