From the Guidelines
Beta blockers should be administered to all patients with a history of myocardial infarction (OMI) without contraindications for their use. The use of beta blockers in patients with OMI has been shown to reduce mortality by 23% in long-term trials, as demonstrated in a systematic review of randomized controlled trials inclusive of 54,234 patients with acute or prior MI 1.
Key Considerations
- Beta blockers decrease myocardial oxygen demand by reducing heart rate, blood pressure, and contractility, and also reduce cardiac automaticity and the risk of ventricular fibrillation (VF) after MI.
- Common contraindications for beta blockers use include heart failure or risk for cardiogenic shock, bradycardia, hypotension, heart block, or active bronchospasm, or acute cocaine ingestion.
- Patients with initial contraindications to beta blockers in the first 24 h after an AMI should be reevaluated to determine their subsequent eligibility.
Recommended Beta Blockers
- Beta blockers without intrinsic sympathomimetic activity are recommended, and in patients with MI complicated with systolic cardiomyopathy with or without heart failure, one of the three proven beta blockers should be used: carvedilol, sustained-release metoprolol succinate, or bisoprolol 1.
- The treatment course with beta blockers for patients with uncomplicated MI is recommended for at least 3 years, but many patients have either hypertension or heart failure/systolic cardiomyopathy and are usually continued on an oral beta blocker indefinitely.
Dosing and Monitoring
- Start with a low dose and titrate up as tolerated, for example, metoprolol tartrate 25mg twice daily, increasing to 50mg twice daily after 1-2 weeks if well-tolerated.
- Carvedilol can be started at 3.125mg twice daily and gradually increased to 25mg twice daily.
- Monitor heart rate, blood pressure, and symptoms of heart failure when initiating therapy, and consider dose reduction rather than discontinuation if side effects occur.
From the FDA Drug Label
Myocardial Infarction The precise mechanism of action of metoprolol in patients with suspected or definite myocardial infarction is not known. The use of beta blockers in patients status post myocardial infarction (OMI) is supported by the fact that metoprolol has been shown to be beneficial in patients with acute myocardial infarction.
- Key points:
- Metoprolol is a beta 1-selective adrenergic receptor blocker.
- It has been shown to reduce heart rate, systolic blood pressure, and cardiac output in patients with acute myocardial infarction.
- The precise mechanism of action in patients with suspected or definite myocardial infarction is not known. Based on the information provided in the drug label for metoprolol 2, it appears that beta blockers, such as metoprolol, can be used in patients status post OMI. However, the precise mechanism of action is not fully understood. In contrast, the drug label for carvedilol 3 provides dosing information for patients with left ventricular dysfunction following myocardial infarction, but does not directly address the use of beta blockers in patients status post OMI.
From the Research
Beta Blockers after Myocardial Infarction
- Beta-blockers are typically prescribed following myocardial infarction (MI) to reduce the risk of reinfarction and mortality 4, 5.
- The choice of beta-blocker may depend on the patient's specific condition, such as left ventricular ejection fraction (LVEF) 4.
- Studies have shown that beta-blockers can reduce the risk of reinfarction and mortality in patients with acute MI, especially those with reduced LVEF 4, 5.
- However, the benefit of beta-blockers in patients with preserved LVEF is less clear, and some studies have suggested that they may not be effective in reducing mortality or reinfarction in these patients 6.
Dosing and Administration
- The optimal dose of beta-blockers after MI is not well established, but studies have suggested that higher doses may be more effective in reducing mortality and reinfarction 4.
- The dose of beta-blockers should be individualized based on the patient's heart rate, blood pressure, and other clinical factors 4.
Comparison of Beta-Blockers
- Different beta-blockers have been compared in terms of their efficacy and safety in patients with acute MI 4, 6.
- Metoprolol and carvedilol are two commonly used beta-blockers that have been shown to be effective in reducing mortality and reinfarction in patients with acute MI 4.
- However, the choice of beta-blocker may depend on the patient's specific condition, such as LVEF, and other clinical factors 4.
Clinical Guidelines and Recommendations
- Clinical guidelines recommend the use of beta-blockers in patients with acute MI, unless contraindicated 7, 8.
- The American College of Cardiology and American Heart Association (ACC/AHA) guidelines recommend the use of beta-blockers in patients with acute MI, unless contraindicated 7.
- The European Society of Cardiology (ESC) guidelines also recommend the use of beta-blockers in patients with acute MI, unless contraindicated 8.