What are the indications and dosing guidelines for Metoprolol (beta-blocker) in patients with hypertension, heart failure, or a history of myocardial infarction?

Metoprolol: Indications and Dosing Guidelines for Hypertension, Heart Failure, and Post-MI Patients

Metoprolol is indicated for hypertension, heart failure with reduced ejection fraction (HFrEF), and secondary prevention after myocardial infarction, with specific dosing regimens for each condition based on clinical presentation and patient risk factors. 1

Indications

1. Heart Failure

• Indicated for patients with left ventricular ejection fraction ≤40% 1
• Reduces all-cause mortality by 34% and sudden death by 41% in heart failure patients 1
• Metoprolol CR/XL (succinate) is the preferred formulation for heart failure 2

2. Post-Myocardial Infarction

• Indicated for secondary prevention after MI to reduce cardiovascular mortality 3
• Long-term use is strongly recommended (Class I, Level of Evidence: A) for secondary prevention in high-risk post-MI patients, particularly those with:
  • Low ejection fraction
  • Heart failure
  • Post-cardiogenic shock (once stabilized) 4

3. Hypertension

• Effective for mild to moderate hypertension 5
• Can be used as monotherapy or in combination with diuretics 5

Dosing Guidelines

Heart Failure Dosing

• Starting dose: 12.5-25 mg metoprolol succinate once daily
• Target dose: 200 mg once daily
• Titration: Gradual increases at 2-week intervals as tolerated 1

Post-MI Dosing

• Acute phase:

  • IV administration should be avoided in patients with signs of heart failure, low output state, or increased risk for cardiogenic shock 4
  • For stable patients without contraindications: 50 mg orally every 6 hours initially, transitioning to 200 mg daily 4

• Maintenance phase:

  • 200 mg controlled-release oral metoprolol daily for hemodynamically stable patients 4

Hypertension Dosing

• Starting dose: 25-50 mg twice daily of immediate-release or 50-100 mg once daily of extended-release
• Maximum dose: 400 mg/day (divided doses for immediate-release)
• Single daily dosing with extended-release formulation is effective for many patients 5

Contraindications

• Heart rate <45 beats/min
• Second or third-degree heart block
• Significant first-degree heart block (P-R interval ≥0.24 sec)
• Systolic blood pressure <100 mmHg
• Moderate-to-severe cardiac failure 3
• Cardiogenic shock or decompensated heart failure requiring IV inotropes 1

Risk Factors for Adverse Effects

Caution is warranted in patients with risk factors for cardiogenic shock:

• Age >70 years
• Systolic blood pressure <120 mmHg
• Heart rate >110 bpm or <60 bpm
• Increased time since symptom onset in STEMI 4

Monitoring and Titration

• Start at low dose and titrate gradually every 2 weeks if tolerated 1
• Monitor heart rate, blood pressure, and clinical status after each dose adjustment 1
• For post-MI patients, initiate with 50 mg orally every 6 hours, then transition to 200 mg daily or maximum tolerated dose 4

Clinical Pearls

• Metoprolol CR/XL (succinate) is preferred over immediate-release (tartrate) for heart failure due to more consistent 24-hour coverage 2
• Beta-blockers with some degree of lipophilicity (like metoprolol) may be more effective at preventing sudden cardiac death compared to hydrophilic beta-blockers 6
• In patients with heart failure and hypertension, metoprolol CR/XL reduces mortality by 39% compared to placebo, with significant reductions in sudden death (49%) and death from worsening heart failure (51%) 7

Common Pitfalls to Avoid

• Avoid IV beta-blockers in STEMI patients with signs of heart failure, low output state, or increased risk for cardiogenic shock 4
• Avoid abrupt discontinuation, which can lead to rebound hypertension or exacerbation of angina
• Avoid rapid dose escalation in heart failure patients, which may precipitate decompensation
• Do not withhold beta-blockers from eligible post-MI patients once stabilized, as long-term therapy significantly reduces mortality 4