Is metoprolol (beta blocker) indicated for a patient with tachycardia and acute myocardial infarction (AMI)?

From the Guidelines

Metoprolol should be used with caution in patients with tachycardia and acute myocardial infarction (AMI), as it may increase the risk of cardiogenic shock, particularly in those with hemodynamic compromise or at high risk of shock 1. When considering the use of metoprolol in this context, it is essential to weigh the potential benefits against the risks. The COMMIT/CCS-2 trial, which randomized 45,852 patients with suspected MI to receive metoprolol or placebo, found that metoprolol was associated with a modest reduction in reinfarction and ventricular fibrillation, but also an increase in cardiogenic shock, particularly in the first 24 hours after hospitalization 1. The 2012 ACCF/AHA focused update incorporated into the ACCF/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction recommends that beta blockers, including metoprolol, be initiated orally in the absence of contraindications, such as cardiogenic shock, severe bradycardia, or high-degree heart block 1. Key considerations when using metoprolol in patients with AMI include:

• Monitoring vital signs closely, particularly blood pressure and heart rate, as beta-blockers can cause hypotension and bradycardia
• Ensuring the patient is adequately volume resuscitated before administration, as beta-blockers can worsen hypotension in hypovolemic patients
• Using caution in patients with cardiogenic shock, severe bradycardia, high-degree heart block, severe COPD, or asthma
• Selecting a beta blocker without intrinsic sympathomimetic activity, such as metoprolol, carvedilol, or bisoprolol, which have been shown to be effective in reducing mortality and morbidity in patients with AMI 1. In summary, while metoprolol may be beneficial in reducing the risk of reinfarction and ventricular arrhythmias in patients with AMI, its use must be carefully considered in the context of the individual patient's risk factors and hemodynamic status, and it should be used with caution and close monitoring 1.

From the FDA Drug Label

Metoprolol tartrate injection is indicated in the treatment of hemodynamically stable patients with definite or suspected acute myocardial infarction to reduce cardiovascular mortality. The answer is yes, metoprolol is indicated for a patient with tachycardia and acute myocardial infarction (AMI), but only if the patient is hemodynamically stable.

• Key points to consider:
  • The patient must have definite or suspected AMI.
  • The patient must be hemodynamically stable.
  • Treatment can be initiated as soon as the patient’s clinical condition allows 2.

From the Research

Indications for Metoprolol in Tachycardia and Acute Myocardial Infarction (AMI)

• Metoprolol, a beta blocker, is often prescribed for patients with tachycardia and acute myocardial infarction (AMI) to reduce myocardial oxygen demand and improve survival rates 3.
• The effectiveness of beta blockers, including metoprolol, in reducing mortality rates in patients with AMI has been established in several large-scale trials 3.
• A study comparing metoprolol and carvedilol in patients with AMI found that overall survival rates were similar for both treatments, but carvedilol may be superior in patients with left ventricular ejection fraction ≤40% 4.
• Another study found that beta blockers, including metoprolol, did not result in a statistically significant reduction in short-term mortality (6-week) following AMI, but may be beneficial for low-risk patients (Killip class I) 5.
• Low doses of metoprolol, bisoprolol, and carvedilol have been shown to not reduce mortality rates in patients with left ventricular dysfunction after AMI 6.
• A meta-analysis of carvedilol versus beta 1 selective beta-blockers (including metoprolol) found that carvedilol significantly reduced all-cause mortality in patients with systolic heart failure and AMI 7.

Considerations for Metoprolol Use

• The decision to prescribe metoprolol for a patient with tachycardia and AMI should be based on individual patient characteristics, including left ventricular ejection fraction and risk profile 4, 5.
• The dosage of metoprolol should be carefully considered, as low doses may not be effective in reducing mortality rates 6.
• Metoprolol should be used in conjunction with other evidence-based treatments for AMI, including aspirin and thrombolytic therapy 3.