Medications for Treating Tachycardia
The first-line medications for treating tachycardia include beta blockers, calcium channel blockers (diltiazem, verapamil), and adenosine, with specific choices depending on the type of tachycardia and patient characteristics. 1
Types of Tachycardia and Medication Selection
Supraventricular Tachycardia (SVT)
- For hemodynamically stable SVT, intravenous beta blockers, diltiazem, or verapamil are recommended as first-line treatment 2, 1
- Adenosine (6-12 mg IV) is highly effective for acute treatment of AVNRT and can also serve as a diagnostic agent 2, 3
- For ongoing management of SVT, oral medications include:
- Beta blockers (metoprolol, propranolol) 1, 4
- Calcium channel blockers (diltiazem, verapamil) 2, 3
- Digoxin (particularly in pregnant patients) 2
- Class IC antiarrhythmics (flecainide, propafenone) in patients without structural heart disease 2
- Class III antiarrhythmics (amiodarone, sotalol, dofetilide) 2, 5
Focal Atrial Tachycardia (AT)
- IV beta blockers, diltiazem, or verapamil are first-line for hemodynamically stable patients 2
- IV adenosine can be effective for diagnosis and may terminate some focal ATs 2
- For refractory cases, IV amiodarone or ibutilide may be considered 2
Multifocal Atrial Tachycardia (MAT)
- IV metoprolol or verapamil is recommended for acute treatment 1, 6
- Oral verapamil, diltiazem, or metoprolol for ongoing management 1
- IV magnesium may be helpful even in patients with normal magnesium levels 1, 6
Specific Medication Details
Beta Blockers
- Examples: metoprolol, propranolol, esmolol 2, 1
- Dosing:
- Particularly effective for sinus tachycardia and SVT 4, 7
- Use with caution in patients with severe pulmonary disease, heart failure, or significant bradycardia 1, 4
Calcium Channel Blockers
- Examples: diltiazem, verapamil 2, 1
- Dosing:
- Effective for AVNRT, MAT, and focal AT 1, 6
- Avoid in patients with severe conduction abnormalities, sinus node dysfunction, or pre-excited AF 1, 3
Adenosine
- Dosing: 6 mg rapid IV bolus, followed by 12 mg if no response within 1-2 minutes (can repeat 12 mg dose once) 2
- Very short half-life makes it ideal for diagnostic purposes 1, 8
- Can cause transient AV block, flushing, chest pain, or dyspnea 2
- Contraindicated in patients with severe asthma 2
Antiarrhythmic Medications
- Class IC (flecainide, propafenone): Effective for SVT in patients without structural heart disease 2
- Class III (amiodarone, sotalol, dofetilide): Used for refractory cases 2, 5
- Amiodarone has numerous drug interactions and requires careful monitoring 5
Special Considerations
Pregnancy
- Safe first-line agents include:
- Second-line agents (if benefits outweigh risks):
- Antiarrhythmic drugs should be avoided in the first trimester when possible 2
Hemodynamically Unstable Patients
- Synchronized cardioversion is recommended for patients with hemodynamically unstable tachycardia 1, 3
- Should be performed promptly when medications fail or aren't feasible 3
Common Pitfalls to Avoid
- Misdiagnosing the type of tachycardia before selecting medication, as treatment varies by mechanism 1, 8
- Using verapamil or diltiazem in patients with ventricular tachycardia misdiagnosed as SVT, which can cause hemodynamic collapse 1
- Failing to identify and treat underlying causes of tachycardia (hyperthyroidism, anemia, dehydration, pain, anxiety) 1, 6
- Overlooking drug interactions, particularly with amiodarone which affects multiple CYP450 enzymes 5
- Using cardioversion for automatic forms of focal AT and MAT, which is often ineffective 1, 3