What is the recommended outpatient management for Supraventricular Tachycardia (SVT)?

Outpatient Management of Supraventricular Tachycardia

For outpatient management of SVT, catheter ablation is the first-line definitive therapy with 94-98% success rates, while oral beta blockers or calcium channel blockers (diltiazem/verapamil) serve as suppressive therapy for patients who decline or are not candidates for ablation. 1, 2

Acute Self-Management for Patients

When SVT episodes occur outside the hospital, patients should be taught:

• Modified Valsalva maneuver (bearing down for 10-30 seconds while supine, then lying flat with legs elevated) is the most effective vagal maneuver with 43.7% initial success rate and 28.1% sustained rhythm conversion at 5 minutes 3, 4
• Standard Valsalva maneuver is less effective (24.2% success) than the modified version 4
• Ice-cold wet towel applied to the face can terminate episodes 1
• Carotid sinus massage (after confirming no bruit) has only 9.1% success rate and should not be the primary recommendation 4

Long-Term Outpatient Pharmacotherapy

When catheter ablation is declined or deferred:

For AVNRT and AVRT (without pre-excitation):

• Oral beta blockers, diltiazem, or verapamil are reasonable suppressive options 1
• These agents prevent recurrence but do not cure the underlying substrate 5

For patients with pre-excitation (WPW pattern):

• Flecainide 50 mg twice daily (can increase by 50 mg increments every 4 days up to maximum 300 mg/day) is indicated for prevention of PSVT in patients without structural heart disease 6
• Avoid AV nodal blocking agents (beta blockers, calcium channel blockers, digoxin) as monotherapy in patients with manifest accessory pathways, as these can enhance accessory pathway conduction during atrial fibrillation and precipitate ventricular fibrillation 1

Definitive Management: Catheter Ablation

Catheter ablation should be offered as first-line therapy for recurrent symptomatic PSVT 5, 2:

• Single procedure success rates: 94.3-98.5% 2
• Particularly recommended for WPW syndrome where there is 0.15-0.24% 10-year risk of sudden cardiac death 1
• Eliminates need for lifelong medication and associated side effects 5

Cardiology Referral Indications

Refer to cardiology for electrophysiology study and potential ablation when:

• Any patient with recurrent symptomatic SVT episodes 5
• First episode in patients with pre-excitation on resting ECG (WPW pattern) 1
• SVT causing tachycardia-mediated cardiomyopathy (1% of cases) 2
• Patients preferring definitive cure over chronic suppressive therapy 5

Critical Safety Considerations

Avoid these common pitfalls:

• Never use verapamil or diltiazem in wide-complex tachycardia of uncertain etiology—this can cause hemodynamic collapse if the rhythm is ventricular tachycardia or pre-excited atrial fibrillation 1
• Do not use AV nodal blockers in patients with known accessory pathways who develop atrial fibrillation—use procainamide or ibutilide instead, or perform immediate cardioversion 1
• Flecainide should not be used in patients with structural heart disease or recent myocardial infarction due to proarrhythmic risk 6
• Avoid calcium channel blockers and beta blockers in patients with systolic heart failure 1

When to Send to Emergency Department

Instruct patients to seek emergency care if:

• Vagal maneuvers fail to terminate the episode within 15-20 minutes 1
• Hemodynamic instability develops (hypotension, altered consciousness, chest pain, severe dyspnea) 1
• Syncope occurs during an episode 1