What medication, such as metoprolol (Metoprolol), can be given to a patient with tachycardia (heart rate of 133) to lower their heart rate?

From the Guidelines

Metoprolol is the most appropriate medication to lower a heart rate of 133 beats per minute, and it can be given intravenously at 2.5–5 mg over 2 minutes, which can be repeated up to 3 doses, as recommended by the 2023 ACC/AHA/ACCp/HRS guideline for the diagnosis and management of atrial fibrillation 1.

Medication Administration

For acute heart rate control, the intravenous administration of metoprolol can be repeated as needed, with a maximum dose of 15 mg.

• The usual oral maintenance dose of metoprolol tartrate is 25–200 mg, twice daily, with an elimination half-life of 3–4 hours.
• The oral maintenance dose of metoprolol succinate is 50–400 mg daily or twice daily, with an elimination half-life of 3–7 hours.

Important Considerations

Before administering metoprolol, it's essential to check the patient's blood pressure, as beta-blockers can cause hypotension.

• Also, assess for contraindications such as severe bradycardia, heart block, cardiogenic shock, or severe bronchospastic disease.
• The medication works by blocking beta-1 adrenergic receptors in the heart, reducing the influence of the sympathetic nervous system and thereby decreasing heart rate and cardiac contractility.

Monitoring and Alternative Medications

Monitor the patient's heart rate, blood pressure, and symptoms after administration.

• If metoprolol is contraindicated or ineffective, alternative medications include diltiazem, verapamil, or digoxin, depending on the underlying cause of the tachycardia, as recommended by the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1 and the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1.

From the FDA Drug Label

CLINICAL PHARMACOLOGY Mechanism of Action Metoprolol is a beta 1-selective (cardioselective) adrenergic receptor blocker. This preferential effect is not absolute, however, and at higher plasma concentrations, metoprolol also inhibits beta 2-adrenoreceptors, chiefly located in the bronchial and vascular musculature Clinical pharmacology studies have demonstrated the beta-blocking activity of metoprolol, as shown by (1) reduction in heart rate and cardiac output at rest and upon exercise, (2) reduction of systolic blood pressure upon exercise, (3) inhibition of isoproterenol-induced tachycardia, and (4) reduction of reflex orthostatic tachycardia Animal and human experiments indicate that metoprolol slows the sinus rate and decreases AV nodal conduction

Metoprolol can be given to a patient with tachycardia (heart rate of 133) to lower their heart rate.

• The medication works by slowing the sinus rate and decreasing AV nodal conduction.
• Metoprolol has been shown to reduce heart rate and cardiac output at rest and upon exercise.
• It is essential to monitor the patient's heart rate and rhythm while receiving metoprolol, especially if they have pre-existing conduction disorders 2.

From the Research

Medication for Tachycardia

• Metoprolol can be used to lower heart rate in patients with tachycardia, as shown in studies 3, 4.
• The medication has been effective in treating multifocal atrial tachycardia, with a significant slowing of heart rate and conversion to sinus rhythm in many patients 3, 4.
• Metoprolol has also been used to treat paroxysmal reentrant supraventricular tachycardia, with some patients experiencing termination of the arrhythmia and others showing a reduction in frequency of attacks 5.
• In patients with inappropriate sinus tachycardia, metoprolol succinate has been compared to ivabradine, with both medications showing a significant reduction in resting heart rate, but ivabradine being more effective in relieving symptoms during exercise or daily activity 6.

Dosage and Administration

• The dosage of metoprolol used in these studies varied, with oral doses ranging from 25-50 mg 4 and intravenous doses of 0.1 mg/kg 5.
• The medication can be administered orally or intravenously, with the oral form taking longer to take effect but being more suitable for long-term management 3, 5.
• The dosage should be adjusted based on the patient's response and tolerance, with careful monitoring of heart rate and blood pressure 7.

Efficacy and Safety

• Metoprolol has been shown to be effective in reducing heart rate and relieving symptoms in patients with tachycardia, with a low risk of adverse effects 3, 4.
• However, the medication should be used with caution in patients with certain medical conditions, such as heart failure or bronchospasm, and the dosage should be adjusted accordingly 7.
• Ivabradine has been shown to be a suitable alternative to metoprolol in patients with inappropriate sinus tachycardia, with a similar effect on resting heart rate but a more significant reduction in symptoms during exercise or daily activity 6.