What is the treatment for recurrent Supraventricular Tachycardia (SVT)?

Treatment for Recurrent Supraventricular Tachycardia (SVT)

Catheter ablation is the recommended first-line therapy for recurrent SVT with success rates of 94-98%, providing a potential cure without the need for chronic medications. 1, 2

Acute Management Algorithm for SVT Episodes

Step 1: Assess Hemodynamic Stability

• If hemodynamically unstable: Proceed directly to synchronized cardioversion (initial biphasic energy 50-100 J) 1
• If hemodynamically stable: Proceed to Step 2

Step 2: Vagal Maneuvers (Success rate ~27.7%)

• Modified Valsalva maneuver is superior (43.7% success rate) compared to standard Valsalva (24.2%) or carotid sinus massage (9.1%) 1, 3
• Technique: Have patient perform strain while seated, then immediately lie flat with legs elevated 4, 3

Step 3: Pharmacological Management (if vagal maneuvers fail)

1. Adenosine: First-line pharmacological agent (91-95% success rate)

   • Initial dose: 6 mg IV rapid push through large vein followed by 20 mL saline flush
   • If ineffective: Can repeat with 12 mg IV after 1-2 minutes
   • Caution: Use with care in severe asthma; may require higher doses in patients on theophylline 1

2. Non-dihydropyridine calcium channel blockers or beta-blockers (if adenosine fails)

   • Verapamil: 2.5-5 mg IV bolus over 2 minutes (3 minutes in older patients)
   • Can repeat 5-10 mg every 15-30 minutes to maximum 20 mg if needed
   • Alternatively: Diltiazem or beta-blockers like metoprolol 1

3. Synchronized cardioversion (if medications fail)

   • Highly effective for terminating SVT
   • Initial energy: 50-100 J, increase in stepwise fashion if unsuccessful 1

Long-Term Management Options

First-Line: Catheter Ablation

• Success rates: 94-98%
• Provides potential cure without need for chronic medications
• Recommended as definitive treatment for recurrent SVT 1, 2, 5

Second-Line: Pharmacological Options

1. First-line medications:

   • Oral beta-blockers (e.g., metoprolol 25-200 mg twice daily)
   • Diltiazem or verapamil 1

2. Second-line medications (for patients without structural heart disease):

   • Flecainide: Indicated for prevention of PSVT and paroxysmal atrial fibrillation/flutter
   • Propafenone
   • Important warning: These medications should be avoided in patients with structural heart disease, ventricular dysfunction, or recent myocardial infarction due to increased risk of proarrhythmia 1, 6

3. "Pill-in-the-pocket" approach:

   • For infrequent, well-tolerated episodes
   • Patient takes oral beta-blocker, diltiazem, or verapamil at onset of symptoms 1

Special Considerations

Medication Cautions

• Dihydropyridine CCBs (including nifedipine) should be avoided for SVT treatment 1
• Flecainide can cause new or worsened arrhythmias (proarrhythmic effects) 6
• Verapamil is contraindicated in wide-complex tachycardias, impaired ventricular function, heart failure, and pre-excited atrial fibrillation/flutter 1

Patient Follow-up

• Refer to cardiology or electrophysiology within 1-2 weeks after initial presentation 1
• Teach patients proper vagal maneuver techniques for home use 1
• Monitor for signs of tachycardia-mediated cardiomyopathy (rare, occurs in ~1% of patients) 2

Special Populations

• Pregnancy: Adenosine is safe due to short half-life; use lowest recommended medication doses 1
• End-stage renal disease: Monitor for electrolyte abnormalities 1

Key Pitfalls to Avoid

• Misdiagnosing SVT type (obtain ECG during tachycardia for accurate diagnosis)
• Using flecainide in patients with structural heart disease (can be fatal)
• Combining verapamil with other AV nodal blocking agents (can cause profound bradycardia)
• Delaying referral for catheter ablation in patients with recurrent episodes