What is the recommended outpatient management for a patient with chronic but paroxysmal supraventricular tachycardia?

Outpatient Management of Chronic Paroxysmal SVT

For chronic paroxysmal SVT in the outpatient setting, catheter ablation should be offered as first-line definitive therapy, with single-procedure success rates of 94.3–98.5% and minimal complications; for patients who decline or are unsuitable for ablation, oral beta-blockers, diltiazem, or verapamil (up to 480 mg/day) are the recommended pharmacologic options. 1, 2

Patient Education and Self-Management

• All patients must be taught vagal maneuvers for self-termination of episodes, performed in the supine position to maximize effectiveness 1, 2
• The modified Valsalva maneuver (bearing down for 10–30 seconds, generating 30–40 mmHg pressure) achieves conversion in approximately 43% of attempts 3, 2
• Carotid sinus massage (5–10 seconds of steady pressure after confirming no bruit) is effective but should be avoided in elderly patients or those with carotid disease 3, 2
• Facial cooling with an ice-cold wet towel (diving reflex) provides an additional option 3, 2

Definitive Treatment: Catheter Ablation (Class I Recommendation)

Electrophysiological study with catheter ablation is the preferred curative approach for symptomatic recurrent SVT, eliminating the need for chronic medication and providing superior outcomes compared to pharmacotherapy 1, 2, 4

• Single-procedure success rates: 94.3–98.5% for AVNRT and AVRT 2, 4
• Low complication rates with experienced operators 1
• Should be offered to all adults with symptomatic recurrent SVT without structural heart disease 2

Pharmacologic Prophylaxis (When Ablation Declined or Unsuitable)

First-Line Agents (Class I)

Oral beta-blockers, diltiazem, or verapamil are the initial pharmacologic choices for ongoing management in patients without ventricular pre-excitation 1, 5, 2

• Verapamil or diltiazem (up to 480 mg/day) reduce SVT episode frequency and duration in randomized trials 1, 5, 2
• Oral beta-blockers (metoprolol, propranolol, atenolol, nadolol) are equally effective with excellent safety profiles 5, 2
• Metoprolol tartrate: start 25 mg twice daily, maximum 200 mg twice daily 5

Second-Line Agents (Class IIa)

Flecainide or propafenone are reasonable when first-line AV nodal blockers fail, showing 86–93% probability of 12-month effectiveness (≤2 attacks) 1, 5, 2

• Flecainide completely suppresses episodes in 65% of patients at 200–300 mg/day 5
• Absolute contraindication: Must never be used in patients with structural heart disease, ischemic heart disease, or left ventricular dysfunction due to proarrhythmic risk 1, 5, 2
• Only appropriate for patients without structural heart disease who are not candidates for or prefer not to undergo catheter ablation 1

Third-Line Agents (Class IIb)

Sotalol (80–160 mg twice daily) may be used when first-line agents fail; can be employed in structural heart disease but requires careful monitoring for proarrhythmia 1, 2

Dofetilide is an option when beta-blockers, calcium channel blockers, flecainide, and propafenone are ineffective or contraindicated 1, 2

Oral amiodarone may be considered only when all other agents are ineffective or contraindicated, but should be avoided as first-line therapy due to potential toxicity and limited efficacy 1, 5

Digoxin has modest efficacy and is reserved for patients unresponsive to or not candidates for first-line agents 1, 5

Critical Safety Considerations

Absolute Contraindications

• Never prescribe flecainide or propafenone to patients with any structural heart disease, ischemic heart disease, or left ventricular dysfunction 1, 5, 2
• Avoid calcium channel blockers in patients with suspected systolic heart failure due to negative inotropic effects 1, 3
• Do not use any AV nodal blocking agent (including beta-blockers or calcium channel blockers) in pre-excited atrial fibrillation or Wolff-Parkinson-White syndrome with AF/flutter, as this can precipitate ventricular fibrillation 5

Medication Adjustments

• Beta-blockers require dose reduction in severe renal dysfunction 5
• Sotalol requires baseline QT interval <460 ms, normal electrolytes, and absence of risk factors for class III drug-related proarrhythmia 1

Treatment Algorithm

1. Offer catheter ablation as first-line definitive therapy to all symptomatic patients 1, 2, 4

2. If ablation declined or unsuitable:

   • Start oral beta-blocker, diltiazem, or verapamil (Class I) 1, 5, 2
   • Teach vagal maneuvers for acute self-management 1, 2

3. If first-line agents fail and no structural heart disease:

   • Add flecainide or propafenone (Class IIa) 1, 5, 2

4. If second-line agents fail:

   • Consider sotalol or dofetilide (Class IIb) 1, 2
   • Amiodarone only as last resort 1, 5

5. Reconsider catheter ablation at any point if symptoms persist or medication side effects occur 2, 4

Comparative Effectiveness

While AV nodal blockers provide moderate symptom reduction, catheter ablation is superior because it offers potential cure, eliminates medication side effects and costs, and achieves >94% success with minimal risk 2, 4. The 2015 ACC/AHA/HRS guidelines emphasize that although many patients prefer potentially curative ablation given its high success rate, pharmacological therapy remains appropriate for those who prefer not to undergo or lack access to ablation 1.