What is the role of beta blockers, such as metoprolol (Beta Blocker) or atenolol (Beta Blocker), in the management of Supraventricular Tachycardia (SVT)?

Role of Beta Blockers in the Management of Supraventricular Tachycardia (SVT)

Beta blockers are effective medications for both acute treatment and ongoing management of SVT. Oral beta blockers are strongly recommended as first-line therapy for ongoing management in patients with symptomatic SVT who do not have ventricular pre-excitation during sinus rhythm. 1

Acute Treatment of SVT

Hemodynamically Stable SVT

• Vagal maneuvers and adenosine are the first-line treatments for acute SVT (Class I recommendation) 1
• Intravenous beta blockers are reasonable for acute treatment in hemodynamically stable patients with SVT (Class IIa recommendation) 1
• Beta blockers have an excellent safety profile, making them appropriate for attempting to terminate SVT in stable patients 1
• In comparative studies, diltiazem was more effective than beta blockers (esmolol) for acute SVT termination, but beta blockers remain a reasonable option 1
• Metoprolol IV has been shown to effectively reduce ventricular rate in 81% of patients with SVT, with significant rate reduction (>15%) in 69% of patients 2

Hemodynamically Unstable SVT

• Synchronized cardioversion is recommended for hemodynamically unstable SVT when vagal maneuvers or adenosine are ineffective or not feasible 1
• Beta blockers should be avoided in hemodynamically unstable patients 1

Ongoing Management of SVT

First-Line Pharmacological Options

• Oral beta blockers, diltiazem, or verapamil are Class I recommendations (highest level) for ongoing management of symptomatic SVT without pre-excitation 1
• Beta blockers are effective in reducing the frequency and duration of SVT episodes 1
• In patients who are not candidates for or prefer not to undergo catheter ablation, beta blockers provide an effective alternative 1

Specific Beta Blockers

• Metoprolol and atenolol are cardioselective beta-1 blockers that slow heart rate and decrease AV nodal conduction 3, 4
• Atenolol has been studied for long-term management in children with SVT, with 59% of patients well-controlled on once-daily dosing (median effective dose 0.7 mg/kg/day) 5
• Propranolol has been studied at doses up to 240 mg/day for SVT management 1

Mechanism of Action in SVT

• Beta blockers work by:
  • Slowing sinus rate 3
  • Decreasing AV nodal conduction 3
  • Reducing heart rate and cardiac output at rest and upon exercise 3
  • Inhibiting catecholamine-induced tachycardia 3, 6

Important Considerations and Precautions

Contraindications and Cautions

• Beta blockers should be avoided in patients with:
  • Decompensated heart failure 4
  • Bronchospastic disease (though cardioselective agents may be used with caution) 4
  • Untreated pheochromocytoma 4
• Caution is needed when using beta blockers with calcium channel blockers (verapamil, diltiazem) due to risk of bradycardia and heart block 4
• Abrupt discontinuation should be avoided due to risk of exacerbation of symptoms 4

Comparative Efficacy

• Electrophysiological study with the option of catheter ablation is considered definitive treatment for SVT and should be considered for patients with frequent or poorly tolerated episodes 1
• For patients who decline ablation or have limited access to electrophysiologists, beta blockers provide effective long-term management 1
• The 2019 ESC guidelines increased the strength of recommendations for beta blockers in acute management of narrow-QRS tachycardias and AVRT compared to previous guidelines 1

Treatment Algorithm for SVT

1. For acute SVT:

   • First: Vagal maneuvers 1
   • Second: Adenosine 1
   • Third: IV beta blockers, diltiazem, or verapamil (if hemodynamically stable) 1
   • Fourth: Synchronized cardioversion (if medications fail or patient is unstable) 1

2. For long-term management:

   • First-line: Catheter ablation (for definitive treatment) 1
   • Alternative: Oral beta blockers, diltiazem, or verapamil 1
   • Second-line (if beta blockers/calcium channel blockers fail): Flecainide or propafenone (in absence of structural heart disease) 1

Beta blockers remain a cornerstone in both acute and chronic management of SVT, offering effective rate control with an excellent safety profile when used appropriately 1, 6.