What is the preferred choice between atenolol (beta blocker) and metoprolol succinate (beta blocker) for managing hypertension and heart failure?

Metoprolol Succinate vs. Atenolol for Hypertension and Heart Failure

Metoprolol succinate is superior to atenolol for managing both hypertension and heart failure due to its proven mortality benefits, extended 24-hour blood pressure control, and established efficacy in heart failure with reduced ejection fraction (HFrEF). 1, 2

Comparative Efficacy in Hypertension

Blood Pressure Control

• Metoprolol succinate provides more consistent 24-hour blood pressure control compared to atenolol:
  • Early morning (12AM-6AM) systolic BP reduction: -7±8 mmHg with metoprolol succinate vs 3±14 mmHg with atenolol (p=0.03) 2
  • Overall 24-hour systolic BP reduction: -9±11 mmHg with metoprolol succinate vs 1±15 mmHg with atenolol (p=0.03) 2

Pharmacokinetic Advantages

• Metoprolol succinate's controlled-release formulation provides:
  • Relatively constant plasma concentrations over 20 hours 3
  • Once-daily dosing convenience with sustained beta-blockade 3
  • More effective control during early morning hours when cardiovascular risk is highest 2

Comparative Efficacy in Heart Failure

Mortality Benefits

• Only three beta-blockers have proven mortality benefits in heart failure: 4, 1

  • Metoprolol succinate (CR/XL)
  • Carvedilol
  • Bisoprolol

• Metoprolol succinate (CR/XL) demonstrated:

  • 34% reduction in relative risk of all-cause mortality in chronic heart failure 5
  • Significant decrease in sudden death and death due to progressive heart failure 5
  • Improved NYHA functional class, exercise capacity, and quality of life 5

Atenolol's Limitations

• Atenolol has not been adequately studied in heart failure 6
• While one small study suggested potential benefits of atenolol in heart failure, guidelines consistently recommend using only the three proven beta-blockers 6, 4

Guideline Recommendations

Heart Failure Guidelines

• The American College of Cardiology/American Heart Association (ACC/AHA) guidelines specifically recommend:
  • Using one of three beta-blockers proven to reduce mortality: bisoprolol, carvedilol, or sustained-release metoprolol succinate (Class I, Level A recommendation) 4
  • Patients who develop heart failure while on other beta-blockers should be switched to one of these three proven agents 4

Hypertension Management

• For patients with both hypertension and heart failure, carvedilol may offer additional advantages due to its combined α1-β1-β2-blocking properties 4
• However, metoprolol succinate remains one of the recommended options with proven mortality benefits 4, 1

Practical Considerations

Dosing and Titration

• Metoprolol succinate:

  • Starting dose: 12.5-25 mg once daily
  • Target dose: 200 mg once daily
  • Gradual titration at 2-week intervals 5

• Atenolol:

  • Typical dosing: 50-200 mg per day 4

Monitoring

• For both agents, monitor:
  • Heart rate and blood pressure
  • Signs of worsening heart failure
  • Symptoms of bradycardia or hypotension 1

Common Pitfalls to Avoid

1. Confusing formulations: Metoprolol tartrate is NOT equivalent to metoprolol succinate - the succinate form has extended release properties and proven heart failure benefits 4, 1

2. Abrupt discontinuation: Never stop beta-blockers abruptly as this may precipitate rebound hypertension or worsening angina 1

3. Inadequate titration: "Start low, go slow" approach is essential, particularly in heart failure patients 4

4. Overlooking contraindications: Avoid in patients with marked first-degree AV block, second/third-degree heart block, severe bradycardia, or decompensated heart failure 4

In conclusion, while both agents can effectively lower blood pressure, metoprolol succinate offers superior 24-hour control and established mortality benefits in heart failure, making it the preferred choice for patients with hypertension, especially those with or at risk for heart failure.