What is the preferred treatment between metoprolol (beta-blocker) and atenolol (beta-blocker) for managing palpitations in sinus tachycardia?

Metoprolol vs Atenolol for Palpitations in Sinus Tachyarrhythmia

Metoprolol is the preferred beta-blocker over atenolol for managing palpitations in sinus tachycardia due to its cardioselectivity, better efficacy in controlling heart rate, and stronger evidence supporting its use in tachyarrhythmias. 1

Comparison of Efficacy

• Metoprolol has been specifically recommended in guidelines for the management of sinus tachyarrhythmias, while atenolol lacks the same level of guideline support for this specific indication 1
• Metoprolol has demonstrated effectiveness in both acute treatment and ongoing management of tachyarrhythmias, including multifocal atrial tachycardia (MAT) and other forms of supraventricular tachycardia 1
• Metoprolol has been shown to effectively reduce heart rate both at rest and during daily activities in patients with inappropriate sinus tachycardia 2
• In studies of supraventricular tachyarrhythmias, metoprolol has demonstrated the ability to both restore sinus rhythm and effectively control ventricular rate 3, 4, 5

Clinical Advantages of Metoprolol

• Metoprolol is relatively cardioselective (beta-1 selective), making it more suitable for patients who may have underlying respiratory conditions 1
• Metoprolol has been successfully used in patients with serious pulmonary disease after correction of hypoxia or other signs of acute decompensation 3, 4
• Metoprolol has been shown to be effective in both intravenous and oral formulations, with the extended-release formulation (metoprolol succinate) providing consistent heart rate control 6, 2
• Metoprolol has demonstrated efficacy in converting patients to sinus rhythm in 68% of cases in some studies, with rapid response when administered intravenously 4

Guideline Recommendations

• The American Academy of Family Physicians and American College of Physicians specifically recommend metoprolol (along with atenolol) for rate control in atrial fibrillation, but metoprolol has more extensive evidence for broader tachyarrhythmia management 1
• The ACC/AHA/HRS guidelines specifically mention metoprolol for the management of multifocal atrial tachycardia and other supraventricular tachycardias 1
• Guidelines state: "Metoprolol is reasonable for ongoing management in patients with recurrent symptomatic MAT" with a Class IIa recommendation 1

Practical Considerations

• Dosing for metoprolol in tachyarrhythmias:

  • Intravenous: 5-15 mg administered slowly (2.5-5 mg over 2 minutes, repeated at 5-minute intervals if needed) 4, 5
  • Oral: Starting with 25-50 mg, titrated as needed up to 200 mg daily 3, 4
  • Extended-release formulation (metoprolol succinate): Up to 190 mg once daily 2

• Contraindications and cautions for both beta-blockers:

  • Severe bradycardia or heart block
  • Decompensated heart failure
  • Severe bronchospastic disease
  • Cardiogenic shock 1

Special Considerations

• In patients with concomitant pulmonary disease, metoprolol may be better tolerated due to its relative cardioselectivity, but should still be used with caution 1, 3
• For patients with significant hypotension concerns, starting with lower doses and careful titration is recommended 2
• In a comparative study between metoprolol succinate and ivabradine for inappropriate sinus tachycardia, metoprolol effectively reduced resting heart rate but was associated with more side effects like hypotension requiring dose reduction 2

Treatment Algorithm

1. First-line treatment: Start with metoprolol (preferably the succinate/extended-release formulation) at 25-50 mg daily 2, 3
2. Titration: Increase dose gradually based on heart rate response and tolerability, up to 200 mg daily 3, 4
3. Monitoring: Assess for:
   • Heart rate control (both at rest and with activity)
   • Blood pressure response
   • Symptom improvement
   • Side effects (fatigue, dizziness, hypotension) 2, 4
4. Alternative: If metoprolol is not tolerated or contraindicated, consider non-dihydropyridine calcium channel blockers (verapamil or diltiazem) 1