What is more effective at treating outpatient Paroxysmal Supraventricular Tachycardia (PSVT), Metoprolol (Lopressor) or Propranolol (Inderal)?

Propranolol and Metoprolol for Outpatient PSVT Treatment

Both propranolol and metoprolol are effective for treating outpatient PSVT, with propranolol showing slightly better evidence for acute termination, particularly when combined with diltiazem in a "pill-in-the-pocket" approach. 1

Effectiveness of Beta Blockers for PSVT

• Beta blockers are considered first-line therapy for ongoing management of PSVT, along with calcium channel blockers (diltiazem and verapamil) 1
• One small randomized study comparing propranolol (240 mg/day) to verapamil and digoxin found that all three medications were similarly effective in reducing episodes and duration of PSVT 1
• Metoprolol has been shown effective in treating PSVT, with studies showing successful conversion to sinus rhythm in 50% of cases with intravenous administration 2, 3
• Propranolol has demonstrated particular efficacy when combined with diltiazem as a "pill-in-the-pocket" approach for acute termination of PSVT 1, 4

Specific Considerations for Each Medication

Propranolol

• Non-selective beta blocker with more extensive evidence in PSVT management 1
• Particularly effective when combined with diltiazem (120 mg diltiazem + 160 mg propranolol) as a "pill-in-the-pocket" approach, with studies showing conversion of PSVT within approximately 27 minutes in 93% of patients 4
• Higher risk of bronchospasm in patients with asthma or COPD due to its non-selective beta-blocking properties 3

Metoprolol

• Cardioselective beta blocker that may be preferred in patients with respiratory conditions 3
• Shown to be effective for acute treatment of PSVT with intravenous administration 2, 3
• Specifically recommended for multifocal atrial tachycardia (MAT), a specific type of PSVT 1
• May have fewer pulmonary side effects compared to propranolol due to its cardioselectivity 3

Clinical Decision Algorithm

1. For patients with infrequent, well-tolerated PSVT episodes:

   • Consider "pill-in-the-pocket" approach with propranolol (preferably combined with diltiazem) 1, 4

2. For patients with frequent PSVT episodes requiring daily prophylaxis:

   • Either propranolol or metoprolol can be effective 1
   • Choose metoprolol for patients with respiratory conditions 3
   • Choose propranolol for patients without respiratory concerns 1

3. For patients with multifocal atrial tachycardia (MAT):

   • Metoprolol is specifically recommended 1

Important Caveats and Pitfalls

• Self-administered "pill-in-the-pocket" beta blockers may cause syncope in some patients - patients should be educated about this risk 1
• Beta blockers should be avoided in patients with decompensated heart failure, severe bradycardia, or high-grade AV block 1
• If oral beta blocker therapy fails to terminate the tachyarrhythmia, patients should seek immediate medical attention 1
• For patients with Wolff-Parkinson-White syndrome and pre-excitation, beta blockers should be used with caution as they may paradoxically increase conduction through accessory pathways during atrial fibrillation 1
• Catheter ablation remains the definitive treatment for recurrent PSVT and should be considered for patients with frequent episodes 1