What oral medications are recommended for a patient with recurrent supraventricular tachycardia (SVT)?

Oral Medications for Recurrent SVT

For patients with recurrent supraventricular tachycardia, oral beta blockers (metoprolol, propranolol, atenolol, nadolol) or nondihydropyridine calcium channel blockers (diltiazem, verapamil) are first-line therapy, with Class Ic antiarrhythmics (flecainide, propafenone) reserved for patients without structural heart disease who fail AV nodal blocking agents. 1

First-Line Oral Therapy

Beta Blockers

The ACC/AHA/HRS guidelines give beta blockers a Class I recommendation for ongoing management of symptomatic SVT without pre-excitation. 1 Specific options include:

• Metoprolol tartrate: Start 25 mg twice daily, maximum 200 mg twice daily 1
• Metoprolol succinate (long-acting): Start 50 mg daily, maximum 400 mg daily 1
• Propranolol: Start 30-60 mg daily (divided or single dose with long-acting formulations), maximum 40-160 mg daily 1
• Atenolol: Start 25-50 mg daily, maximum 100 mg daily 1
• Nadolol: Start 40 mg daily, maximum 320 mg daily 1

Beta blockers reduce both the frequency and duration of SVT episodes and have an excellent safety profile. 2, 3

Nondihydropyridine Calcium Channel Blockers

These agents also carry a Class I recommendation for ongoing SVT management. 1

• Verapamil: Doses of 360-480 mg/day have demonstrated efficacy in reducing episode frequency and duration in randomized trials 1
• Diltiazem: Effective alternative with similar mechanism of action 1, 4

Small randomized trials showed oral verapamil (480 mg/day), propranolol (240 mg/day), and digoxin (0.375 mg/day) had similar efficacy, with all three medications well tolerated. 1

Second-Line Therapy: Class Ic Antiarrhythmics

For patients without structural heart disease who do not respond to AV nodal blocking agents, flecainide and propafenone are the preferred second-line choices. 1

Flecainide

• Starting dose for PSVT: 50 mg every 12 hours 5
• Dose titration: May increase in increments of 50 mg twice daily every four days until efficacy is achieved 5
• Maximum dose for paroxysmal supraventricular arrhythmias: 300 mg/day 5
• Efficacy: Completely suppresses episodes in 65% of patients at doses between 200-300 mg/day, with double-blinded, placebo-controlled trials confirming efficacy 1

Critical contraindication: Flecainide should not be used in patients with structural heart disease or significant ventricular dysfunction. 1, 5

Propafenone

Similar efficacy profile to flecainide for patients without structural heart disease. 1, 4

Third-Line Therapy

Digoxin and Amiodarone

These agents are generally reserved as third-line therapy due to potential adverse effects. 1

• Digoxin: Modest efficacy, reserved for patients unresponsive to or not candidates for first-line agents 1
• Amiodarone: Effective in suppressing AVNRT but has significant potential toxicity and should only be used when other therapies are ineffective or contraindicated (Class IIb recommendation) 1, 2

The European Society of Cardiology downgraded amiodarone for SVT management, recommending it only as a last-resort option due to limited evidence and potential toxicity. 2

Class Ia Antiarrhythmics

Quinidine, procainamide, and disopyramide have limited appeal due to multidosing regimens, modest efficacy, and adverse/proarrhythmic effects. 1, 4 These are rarely used today. 1

Important Clinical Caveats

Avoid in Pre-excitation

Never use AV nodal blocking agents (beta blockers, calcium channel blockers, digoxin) in patients with pre-excited atrial fibrillation or Wolff-Parkinson-White syndrome with AF/flutter, as this can precipitate ventricular fibrillation. 2

Structural Heart Disease

Class Ic agents (flecainide, propafenone) are contraindicated in patients with structural heart disease, coronary artery disease, or left ventricular dysfunction. 1, 5

Dosing Adjustments

• Beta blockers require dose reduction in severe renal dysfunction 1
• Flecainide requires careful monitoring in renal impairment (initial dose 100 mg once daily if creatinine clearance ≤35 mL/min/1.73 m²) 5
• Steady-state plasma levels with flecainide may not be achieved until 3-5 days of therapy; increase dosage no more frequently than every four days 5

Alternative Consideration: Catheter Ablation

Catheter ablation should be strongly considered as first-line definitive therapy, with single procedure success rates of 94.3%-98.5%, recurrence rates <5%, and inadvertent heart block in <1% of patients. 4, 3 This is particularly appropriate for patients with frequent or poorly tolerated episodes. 2, 3