What medications are used to treat tachycardia?

Medications for Tachycardia

The treatment of tachycardia depends primarily on the type of tachycardia (narrow-complex vs. wide-complex) and the hemodynamic stability of the patient, with specific medications selected based on these factors. 1

Initial Assessment and Stabilization

• Hemodynamic stability assessment is crucial:
  • Unstable signs requiring immediate electrical cardioversion: systolic BP ≤90 mmHg, chest pain, heart failure, or heart rate ≥150 beats/min with symptoms 1
  • For stable patients, proceed with pharmacological management based on tachycardia type

Narrow-Complex Tachycardia (Supraventricular Tachycardia)

First-line approaches:

1. Vagal maneuvers (Valsalva, carotid sinus massage after confirming absence of carotid bruit) 1
2. IV adenosine (6mg rapid bolus, may repeat with 12mg if ineffective) 1, 2
   • Extremely short half-life (few seconds)
   • Success rate of approximately 93% for SVT 2
   • Common transient side effects: chest discomfort, dyspnea, flushing 2

Second-line medications:

• Calcium channel blockers: IV verapamil or diltiazem 1, 3
• Beta-blockers: particularly effective for AVNRT 1, 3

Long-term prevention:

• For AVNRT: Calcium channel blockers or beta-blockers (target the slow pathway) 3
• For accessory pathway tachycardias: Sodium channel blockers (propafenone, flecainide) 3
• For atrial tachycardias: Propafenone, flecainide, or sotalol 3
• For drug-resistant cases: Amiodarone or consider catheter ablation 3

Wide-Complex Tachycardia (Ventricular Tachycardia)

For hemodynamically unstable VT:

• Immediate synchronized electrical cardioversion (100J, 200J, 360J as needed) 1
• Follow with antiarrhythmic drugs if recurrent 4

For hemodynamically stable VT:

• Lidocaine (Lignocaine): First choice for VT 5

  • IV dose: 1-3 mg/kg
  • For cardiac arrest: 100 mg bolus, may repeat after 5-10 minutes
  • Maintenance: IV infusion of 2-4 mg/min after successful cardioversion 5

• Amiodarone: For VT refractory to other therapies 6

  • Class III antiarrhythmic with properties of all four Vaughan Williams classes 6
  • Dose: 150 mg over 10 min, followed by infusion 1
  • Particularly useful for VT with heart failure or acute myocardial infarction 1

• Procainamide: For monomorphic VT without heart failure or AMI 1

  • Dose: 10 mg/kg 1

Atrial Fibrillation with Rapid Ventricular Response

• Beta-blockers or diltiazem: First-line for rate control 1
• For rhythm control: Consider ibutilide, dofetilide, flecainide, or amiodarone 1
• For patients with heart failure: Digoxin and amiodarone 1

Important Considerations and Pitfalls

• Always correct reversible causes:

  • Electrolyte abnormalities (maintain K+ >4.0 mEq/L, Mg2+ >2.0 mg/dL) 1
  • Ischemia (consider urgent coronary revascularization if evidence of acute ischemia) 1
  • Drug toxicity, thyroid disorders 1

• Critical pitfalls to avoid:

  • Never give verapamil or diltiazem for wide-complex tachycardias of uncertain origin - can precipitate hemodynamic collapse in VT 1
  • Never delay electrical cardioversion in unstable patients 1
  • Never administer lidocaine for SVT - it has no effect on supraventricular tachycardia 5

• For refractory cases:

  • Consider catheter ablation (success rates 80-95% for SVT) 1
  • For VT refractory to lidocaine, consider amiodarone or implantable cardioverter/defibrillator for secondary prevention 6, 4