When to initiate medication in tachycardia (rapid heart rate)?

From the Guidelines

Medication for tachycardia should be started when the heart rate exceeds 100 beats per minute and is causing symptoms or hemodynamic compromise, or when the underlying cause cannot be adequately addressed through non-pharmacological means, as recommended by the most recent guidelines 1.

Key Considerations

• First-line medications include beta-blockers such as metoprolol or atenolol, which work by blocking sympathetic stimulation to slow the heart rate.
• For atrial fibrillation or flutter, calcium channel blockers like diltiazem or verapamil may be preferred.
• In emergency situations with unstable tachycardia, adenosine can terminate supraventricular tachycardias.
• For ventricular tachycardias, amiodarone may be necessary.

Medication Options

• Beta-blockers: metoprolol (25-100 mg twice daily) or atenolol (25-100 mg once daily) 1.
• Calcium channel blockers: diltiazem (120-360 mg daily in divided doses) or verapamil (120-360 mg daily in divided doses) 1.
• Adenosine: 6 mg rapid IV push, followed by 12 mg if needed 1.
• Amiodarone: 150 mg IV over 10 minutes, followed by infusion 1.

Important Notes

• Before starting medication, it's essential to identify and treat underlying causes such as fever, dehydration, anemia, hyperthyroidism, or anxiety.
• These medications work by modulating the electrical conduction system of the heart, either by decreasing automaticity of pacemaker cells, prolonging the refractory period, or blocking specific ion channels involved in cardiac conduction.
• The choice of medication depends on the type of tachycardia, underlying heart disease, and patient characteristics, as outlined in the guidelines 1.

From the FDA Drug Label

In patients with definite or suspected acute myocardial infarction, treatment with atenolol I. V. Injection should be initiated as soon as possible after the patient’s arrival in the hospital and after eligibility is established.

Atenolol I.V. Injection should be administered under carefully controlled conditions including monitoring of blood pressure, heart rate, and electrocardiogram.

The medication atenolol should be started in patients with tachycardia due to acute myocardial infarction as soon as possible after arrival in the hospital and after eligibility is established, under carefully controlled conditions.

• The initial dose is 5 mg atenolol I.V. over 5 minutes, followed by another 5 mg atenolol I.V. 10 minutes later.
• Atenolol tablets 50 mg should be initiated 10 minutes after the last I.V. dose, followed by another 50 mg oral dose 12 hours later.
• Key considerations for initiating atenolol include monitoring of blood pressure, heart rate, and electrocardiogram 2.

From the Research

Determining the Appropriate Time to Start Medication in Tachycardia

The decision on when to start medication in tachycardia depends on various factors, including the severity of symptoms, the type of tachycardia, and the presence of underlying cardiac disease.

• The management of tachycardia should address any underlying cardiac disease process 3.
• Symptomatic tachycardia requires a quick and authoritative diagnosis on an ECG and the application of adequate emergency treatment, which may involve medical and electrical treatment options 4.
• Assessment and treatment of patients with acute tachyarrhythmia should be based on the predominant acute tachyarrhythmias, focusing on the assessment and management of patients using case study examples 5.
• Management strategies for tachycardia include the treatment of underlying causes, and the use of antiarrhythmic medications, which can be effective in reducing symptoms, but may have frequent side effects 3, 6.

Key Considerations

• Tachycardia can be physiological or pathological in origin, and various adverse consequences have been recognized, including the association between persistent tachycardia and cardiomyopathy 6.
• Nonpharmacological strategies, such as catheter ablation, have evolved and offer long-term cure in the majority of patients, but pharmacotherapy retains an important place in the therapeutic approach to cardiac arrhythmias in many patients 3.
• A structured approach to analyzing and treating arrhythmias is necessary, including a practical categorization of the multitude of tachycardias, with medical and electrical treatment options and ECG examples 4.