Beta-blockers

Modes of action and cardiovascular effects

• Modes of action: beta-blockers antagonise the effect of beta-adrenergic stimuli [1].
• Cardiovascular effects: beta-blockers reduce heart rate, cardiac contractility, and systolic blood pressure. They also have anti-arrhythmic effects since they decrease spontaneous firing of ectopic pacemakers, slow conduction, and increase the refractory period of the atrioventricular (AV) node [1].
• Classification: beta-blockers can be classified as non-selective (combined β1 and β2 blockers) or cardioselective β1-antagonists (see Table 1).

Indications

Acute coronary syndrome

• Beta-blockers reduce mortality and reinfarction by 20-25% in those who have recovered from an infarction [1].
• Oral treatment with beta-blockers should be considered for all ST-elevation myocardial infarction (STEMI) patients without contraindications (Class IIa, Level B) [2]. They are indicated if STEMI patients also have heart failure or LV dysfunction (Class I, Level A) [2].

Stable coronary artery disease

• Beta-blockade is a very effective symptomatic treatment, alone or combined with another drug, for most of patients with classical angina [1].
• Beta-blockers and/or calcium channel blockers are first-line treatment to control heart rate and anginal symptoms (Class I, Level A) [3].

Heart Failure

• Beta-blockers have been shown to reduce mortality and heart failure readmissions in patients with heart failure with a reduced ejection fraction (HFrEF) [1].
• Beta-blockers are recommended, in addition to ACE inhibitors, for patients with stable, symptomatic HFrEF (Class I, Level A) [4].
• Bisoprolol, Carvedilol, Metoprolol and Nebivolol are licensed for use in HFrEF and should be preferred [4].

Arrhythmia

• Beta-blockers can be used to slow the heart rate in patients with arrhythmias such as atrial flutter and/or atrial fibrillation [1].
• They are effective in the control of ventricular arrhythmias related to sympathetic activation, acute coronary syndrome, and heart failure; including the prevention of sudden cardiac death [1].

Contraindications and side effects

• The most frequent side effects of beta-blockers include: hypotension, bradycardia, bronchospasm, cold extremities, fatigue, headache, sleep disturbances and increased insulin resistance [1].
• High-degree AV block is an absolute contraindication (if no pacemaker) [1].
• Use cardioselective beta-blockers in case of chronic obstructive pulmonary disease (COPD); start low and go slow [1].
• Asthma is a relative contraindication for the use of beta-blockers [4]. These drugs should be used with caution and preferably with specialist advice.

Types and typical dosages of the most frequently used beta-blockers [1].

Practical recommendations for the use of beta-blockers in daily practice [1]

• Beta-blockers are very effective for the symptomatic treatment of patients with effort angina or arrhythmias.
• Most evidence for the reduction of cardiovascular events by beta-blockers concerns acute coronary syndrome patients; especially in the presence of LV dysfunction.
• High-degree AV block (without a pacemaker) is an absolute contraindication.
• Asthma is a relative contraindication.
• COPD is a relative contraindication.
• Start low and go slow with the elderly, COPD, and patients with heart failure.
• The most frequent side effects include: hypotension, bronchospasm, central effects, and increased insulin resistance.
• In case of HFrEF: Use evidence-based beta-blockers: carvedilol, bisoprolol, metoprolol, nebivolol.
• In case of HFrEF: Start low and go slow (up-titration after at least 2 weeks).
• In case of HFrEF: In case of an episode of exacerbation of heart failure, start after clinical stabilization only.