What are the treatment options for tachycardia?

Treatment of Tachycardia

The treatment of tachycardia depends critically on hemodynamic stability and the type of tachycardia present—unstable patients require immediate synchronized cardioversion, while stable patients with narrow-complex tachycardia should receive adenosine or AV nodal blocking agents (beta-blockers, diltiazem, verapamil), and stable wide-complex tachycardia should be treated with procainamide or amiodarone. 1, 2

Initial Assessment: Hemodynamic Stability

The first and most critical decision point is determining hemodynamic stability. 1, 2

• Unstable patients (hypotension with systolic BP ≤90 mmHg, chest pain, heart failure, altered mental status, signs of shock, or heart rate ≥150 bpm) require immediate synchronized cardioversion regardless of tachycardia type 3, 2
• Cardioversion should be performed at 100J, then 200J, then 360J if initial attempts fail 3
• In conscious patients, provide sedation prior to cardioversion 2
• Do not delay cardioversion in unstable patients to attempt pharmacological conversion 2

Narrow-Complex Tachycardia (QRS <120ms) in Stable Patients

Supraventricular Tachycardia (SVT)

For stable SVT, the treatment algorithm proceeds as follows: 1

1. First-line: Vagal maneuvers (Valsalva maneuver or carotid massage if no carotid bruit present) 3

2. Second-line: IV Adenosine 3, 1

   • Adenosine is the drug of choice for terminating AV nodal re-entrant tachyarrhythmias 3
   • Dosing: 3mg rapid IV bolus followed by saline flush; if no effect after 1-2 minutes, give 6mg; maximum dose 12mg 3
   • Critical advantage: Extremely short half-life (<60 seconds), making it ideal for both diagnosis and treatment 1
   • Contraindications: Avoid in asthmatics (can precipitate bronchospasm) 3
   • Must be given in monitored environment (ED or critical care) as it can cause transient complete heart block 3
   • Side effects (flushing, chest pain) are common but last <60 seconds 3

3. Alternative agents if adenosine fails or is contraindicated: 3, 1

   • IV beta-blockers (metoprolol 5mg slow IV bolus, can repeat if tolerated) 1
   • IV diltiazem (5-10mg over 60 seconds) 3, 1
   • IV verapamil (5-10mg over 60 seconds) 3, 1

Multifocal Atrial Tachycardia (MAT)

• First-line acute treatment: IV metoprolol or IV verapamil 1
• Address underlying conditions: Pulmonary disease and electrolyte abnormalities must be corrected 1
• IV magnesium may be helpful even with normal magnesium levels 1
• Cardioversion is ineffective for MAT and should not be attempted 1

Atrial Fibrillation with Rapid Ventricular Response

• Beta-blockers and diltiazem are drugs of choice for acute rate control 3
• Digoxin and amiodarone may be used in patients with congestive heart failure 3
• Amiodarone may also result in cardioversion to normal sinus rhythm 3

Wide-Complex Tachycardia (QRS ≥120ms) in Stable Patients

Critical pitfall: Wide-complex tachycardia should be assumed to be ventricular tachycardia (VT) until proven otherwise. 2

Treatment Algorithm for Stable Wide-Complex Tachycardia

1. For monomorphic VT without severe heart failure or acute MI: Procainamide is the recommended first-line agent 3, 2

2. For monomorphic VT with or without severe heart failure or acute MI: Amiodarone is recommended 3, 2, 4

   • Dosing: 5mg/kg (300mg) over one hour; in life-threatening situations can be given over 15 minutes 3
   • Loading dose of 15mg/kg (up to 900mg) over next 24 hours 3
   • Antiarrhythmic effect may take up to 30 minutes 3

3. For regular monomorphic wide-complex tachycardia of uncertain etiology: IV adenosine may be considered for both diagnosis and treatment 3, 2

   • Critical warning: Adenosine should NEVER be given for unstable, irregular, or polymorphic wide-complex tachycardia as it may cause degeneration to ventricular fibrillation 2

4. Sotalol may be considered for hemodynamically stable sustained monomorphic VT, including patients with acute MI 3

Polymorphic Wide-Complex Tachycardia

• For polymorphic VT associated with long QT syndrome: IV magnesium, pacing, and beta-blockers are recommended 2
• Avoid isoproterenol in this setting 2

Critical Pitfalls to Avoid

1. Misdiagnosing VT as SVT with aberrancy 2

• Never use verapamil or diltiazem for wide-complex tachycardia unless you are certain it is SVT—these agents can cause hemodynamic collapse in VT 1, 2
• When in doubt, treat as VT

2. Inappropriate drug combinations 3

• Verapamil is contraindicated if beta-blockers have already been given 3

3. Failing to identify the specific tachycardia type 1

• Treatment varies significantly by mechanism—obtain a 12-lead ECG during tachycardia whenever possible 1

4. Using cardioversion for automatic tachycardias 1

• Cardioversion is ineffective for focal atrial tachycardia and MAT 1

Tachycardia-Induced Cardiomyopathy

For patients with tachycardia-induced cardiomyopathy, aggressive rhythm or rate control is mandatory to prevent irreversible cardiac damage. 3

• Maintenance of sinus rhythm or control of ventricular rate is indicated (Level of Evidence B) 3
• Catheter ablation may be required and is often curative 3
• Standard heart failure therapy should be used to attenuate adverse remodeling 3
• Target heart rate <100 bpm, as rates >100 bpm can lead to cardiomyopathy 3
• Critical warning: Sudden death has been described even after rhythm control and near-normalization of ejection fraction, suggesting persistent ultrastructural changes 3

Ongoing Management Considerations

Junctional Tachycardia (Chronic Management)

• Oral beta-blockers are reasonable as first-line chronic therapy 3
• Oral diltiazem or verapamil are reasonable alternatives 3
• Beta-blockers are preferred due to proarrhythmic effects and long-term toxicity of other agents 3

Referral Indications

• All patients treated for SVT should be referred to a heart rhythm specialist 5
• Catheter ablation is an option for patients with persistent or recurrent SVT unable to tolerate long-term pharmacologic management 6, 5
• Expedient cardiology referral is warranted for Wolff-Parkinson-White syndrome, as ablation is potentially curative 6