From the Guidelines
Beta blockers are strongly recommended for all eligible patients following a myocardial infarction (MI) as they significantly reduce mortality, with a 23% reduction in the odds of death in long-term trials, as demonstrated in a systematic review of randomized controlled trials inclusive of 54,234 patients 1. The role of beta blockers in the management of patients post-myocardial infarction (post-MI) is well established, with benefits including reduction of myocardial oxygen demand, prevention of arrhythmias, and limitation of infarct size and adverse remodeling.
- Common beta blockers used post-MI include carvedilol, sustained-release metoprolol succinate, and bisoprolol, which are preferred due to their proven efficacy in patients with MI complicated by systolic cardiomyopathy with or without heart failure 1.
- Treatment with beta blockers should begin within 24 hours of MI if the patient is hemodynamically stable, and continue indefinitely, ideally for life, as recommended by the AHA/ACCF secondary prevention guidelines for patients with uncomplicated MI 1.
- Contraindications for beta blocker use include heart failure or risk for cardiogenic shock, bradycardia, hypotension, heart block, or active bronchospasm, or acute cocaine ingestion, and patients with initial contraindications should be reevaluated to determine their subsequent eligibility 1.
- Patients should be monitored for side effects such as fatigue, bradycardia, hypotension, and worsening heart failure symptoms, and if side effects occur, dose reduction rather than discontinuation is preferred whenever possible. The benefits of beta blockers in post-MI patients are most pronounced in those with complicated MI, including heart failure, systolic cardiomyopathy, or ventricular arrhythmias, as evidenced by the systematic review 1.
From the FDA Drug Label
By blocking the positive chronotropic and inotropic effects of catecholamines and by decreasing blood pressure, atenolol generally reduces the oxygen requirements of the heart at any given level of effort, making it useful for many patients in the long-term management of angina pectoris In a multicenter clinical trial (ISIS-1) conducted in 16,027 patients with suspected myocardial infarction, patients presenting within 12 hours (mean = 5 hours) after the onset of pain were randomized to either conventional therapy plus atenolol (n = 8,037), or conventional therapy alone (n = 7,990) During the treatment period (days 0 to 7), the vascular mortality rates were 3. 89% in the atenolol group (313 deaths) and 4.57% in the control group (365 deaths). The mechanism through which atenolol improves survival in patients with definite or suspected acute myocardial infarction is unknown, as is the case for other beta-blockers in the postinfarction setting. Atenolol, in addition to its effects on survival, has shown other clinical benefits including reduced frequency of ventricular premature beats, reduced chest pain, and reduced enzyme elevation
Beta blockade with atenolol is beneficial in the management of patients post-myocardial infarction (post-MI), as it:
- Reduces oxygen requirements of the heart
- Decreases vascular mortality rates
- Shows clinical benefits such as reduced frequency of ventricular premature beats, reduced chest pain, and reduced enzyme elevation Key points to consider:
- Contraindications to beta blockade include patients dependent on sympathetic stimulation for maintenance of adequate cardiac output and blood pressure
- Elderly patients may require dose adjustments due to decreased renal function and increased sensitivity to beta blockers
- Treatment should be initiated as soon as possible after the patient's arrival in the hospital and after eligibility is established, with careful monitoring of blood pressure, heart rate, and electrocardiogram 2 2
From the Research
Role of Beta Blockers in Post-MI Management
- Beta blockers significantly decrease the risk of mortality in patients after myocardial infarction (MI) 3.
- They reduce the risk of reinfarction and mortality in both the immediate and long term after an MI 3.
- Guidelines recommend that post-MI patients should be started on beta-blocker therapy and continued indefinitely, unless absolutely contraindicated or not tolerated 3.
Long-Term Beta-Blocker Therapy
- In the reperfusion era, short-term beta-blocker therapy has been demonstrated to reduce recurrent MI and angina, but not mortality 4.
- The majority of included studies failed to demonstrate a benefit in survival or cardiovascular events with long-term beta-blockers in post-MI patients with normal left ventricular function 4.
- It may be reasonable to discontinue beta-blockers in patients without impaired left ventricular function at 1-year post-MI who do not have another indication for use 4.
Benefits and Harms of Beta Blockers
- Beta-blockers probably reduce the risks of all-cause mortality and myocardial reinfarction in patients younger than 75 years of age without heart failure following acute myocardial infarction 5.
- Beta-blockers may further reduce the risks of major cardiovascular events and cardiovascular mortality compared with placebo or no intervention in patients younger than 75 years of age without heart failure following acute myocardial infarction 5.
- The effects of beta-blockers on serious adverse events, angina, and quality of life are unclear due to sparse data or no data at all 5.
Comparison of Beta Blockers
- Carvedilol significantly reduced all-cause mortality compared to β(1)-selective beta-blockers (atenolol, bisoprolol, metoprolol, and nebivolol) in systolic heart failure patients 6.
- Carvedilol significantly reduced all-cause mortality compared with β(1)-selective beta-blockers in acute myocardial infarction patients using the fixed-effects model 6.
- The choice of beta blocker is important as benefit is not a class-effect, with bisoprolol, metoprolol succinate, and carvedilol being the most effective options 7.