What is the treatment for supraventricular tachycardia (SVT)?

Treatment of Supraventricular Tachycardia (SVT)

The treatment of SVT should follow a stepwise approach starting with vagal maneuvers, followed by adenosine, then calcium channel blockers or beta blockers, and synchronized cardioversion for hemodynamically unstable patients, with catheter ablation as the definitive long-term treatment for recurrent cases. 1

Acute Management

First-Line Treatments

1. Vagal Maneuvers (Class I, Level B-R) 2, 1

   • Should be performed with patient in supine position
   • Techniques include:
     • Valsalva maneuver: bearing down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg)
     • Modified Valsalva maneuver: more effective with 43.7% success rate 3
     • Carotid sinus massage: steady pressure over carotid sinus for 5-10 seconds (after confirming absence of bruit)
     • Facial application of ice-cold wet towel

2. Adenosine (Class I, Level B-R) 2, 1

   • Indicated when vagal maneuvers fail
   • Highly effective with approximately 91% success rate
   • Acts as both diagnostic and therapeutic agent
   • Administered as rapid IV bolus

Second-Line Treatments (for hemodynamically stable patients)

1. IV Calcium Channel Blockers (Class IIa, Level B-R) 2, 1

   • Options: diltiazem or verapamil
   • Particularly effective for AVNRT
   • Contraindicated in suspected pre-excited AF or VT

2. IV Beta Blockers (Class IIa, Level B-R) 2, 1

   • Options include esmolol, metoprolol
   • Alternative to calcium channel blockers
   • Good safety profile but less effective than calcium channel blockers

Emergency Treatment

• Synchronized Cardioversion (Class I, Level B-NR) 2, 1
  • Immediate treatment for hemodynamically unstable patients
  • Also indicated when pharmacological therapy fails or is contraindicated
  • Highly effective in terminating SVT

Long-Term Management

Definitive Treatment

• Catheter Ablation (Class I, Level B-NR) 1, 4
  • Recommended for recurrent symptomatic SVT
  • Success rates of 94-98%
  • Provides potential cure without need for chronic medications
  • Should be considered first-line for long-term management

Pharmacological Options

1. AV Nodal Blockers (Class I, Level B-R) 1

   • Oral beta blockers, diltiazem, or verapamil
   • For patients without ventricular pre-excitation

2. Class IC Antiarrhythmics (Class IIa, Level B-R) 1, 5

   • Options: flecainide, propafenone
   • IMPORTANT SAFETY CONSIDERATION: Contraindicated in patients with structural heart disease, ischemic heart disease, or recent myocardial infarction due to significant proarrhythmic risk 5
   • Flecainide specifically indicated for prevention of PSVT 5

3. Ivabradine (Class IIa, Level B-R) 1

   • Dosage: 2.5-7.5 mg twice daily
   • Alternative option for ongoing management

Special Considerations

Hemodynamic Status

• Always assess hemodynamic stability first
• Unstable patients (hypotension, altered mental status, chest pain, heart failure) require immediate synchronized cardioversion 2, 1
• Do not delay cardioversion to administer medications in unstable patients 1

Medication Cautions

• Avoid vagal maneuvers in hypotensive patients as they may worsen hemodynamic status 1
• Monitor for proarrhythmic effects with antiarrhythmic medications, especially flecainide 5
• In flecainide-treated patients with SVT, proarrhythmic events occurred in 4% of patients, with higher risk in those with paroxysmal atrial fibrillation 5

Follow-up Care

• Cardiology referral within 1-2 weeks after initial presentation 1
• Consider electrophysiology study for definitive diagnosis and treatment
• Monitor patients on medication therapy for side effects and efficacy

Treatment Algorithm

1. Assess hemodynamic stability
2. If stable:
   • Start with vagal maneuvers
   • If unsuccessful, administer adenosine
   • If adenosine fails, use IV calcium channel blockers or beta blockers
   • If pharmacological therapy fails, proceed to synchronized cardioversion
3. If unstable:
   • Immediate synchronized cardioversion
4. For long-term management:
   • Refer to cardiology/electrophysiology
   • Consider catheter ablation as definitive treatment
   • If ablation not feasible, use appropriate pharmacological therapy based on patient characteristics

The modified Valsalva maneuver has shown superior efficacy (43.7% success) compared to standard Valsalva (24.2%) and carotid sinus massage (9.1%) 3, making it the preferred vagal maneuver technique.