What is the significance of bradycardia in a 79-year-old patient taking metoprolol (beta blocker) 12.5 mg twice daily (bd)?

From the Guidelines

I strongly recommend reducing or discontinuing the metoprolol due to symptomatic bradycardia in this 79-year-old patient. The current heart rate of 47 beats per minute is significantly below normal range and potentially dangerous, especially in an elderly individual. Metoprolol, a beta-blocker, is directly contributing to this bradycardia by slowing the heart rate 1.

Key Considerations

• The patient should be evaluated promptly by their healthcare provider who may initially reduce the dose to 6.25 mg once daily or temporarily discontinue the medication while monitoring for rebound effects.
• During this transition, the patient should monitor their pulse daily and report any dizziness, fainting, confusion, or chest pain immediately as these could indicate inadequate cardiac output.
• The underlying reason for metoprolol therapy (hypertension, heart failure, or post-myocardial infarction management) should be reassessed, and alternative medications that don't cause bradycardia might be considered.
• Elderly patients often require lower doses of beta-blockers due to age-related changes in drug metabolism and increased sensitivity to these medications 1.

Management Approach

• According to the guidelines, patients with significant sinus bradycardia (heart rate less than 50 beats per minute) should not receive acute beta-blocker therapy until these conditions have resolved 1.
• The patient's condition should be closely monitored, and the healthcare provider should be prepared to adjust the treatment plan as needed to ensure the patient's safety and well-being.
• It is essential to consider the potential risks and benefits of continuing metoprolol therapy in this patient, weighing the potential benefits of beta-blockade against the risks of bradycardia and other adverse effects 1.

From the FDA Drug Label

Bradycardia, including sinus pause, heart block, and cardiac arrest have occurred with the use of metoprolol. Patients with first-degree atrioventricular block, sinus node dysfunction, or conduction disorders may be at increased risk. Monitor heart rate and rhythm in patients receiving metoprolol. If severe bradycardia develops, reduce or stop metoprolol The patient's pulse is 47/min, which is considered bradycardia.

• The patient is on metoprolol 12.5 mg bd, which may be contributing to the bradycardia.
• The FDA drug label recommends to monitor heart rate and rhythm in patients receiving metoprolol, and to reduce or stop metoprolol if severe bradycardia develops 2. Considering the patient's age (79 yr) and the potential risks associated with bradycardia, it is recommended to reduce or stop metoprolol to prevent further complications.

From the Research

Patient Profile

• Age: 79 years
• Pulse: 47/min
• Medication: Metoprolol 12.5 mg twice daily

Relevant Studies

• A study published in 2012 3 found that beta-blockers, including metoprolol succinate, can reduce mortality and hospitalization in patients with heart failure, and that initiating dose should be very low (12.5 mg metoprolol succinate) and increased gradually over weeks.
• Another study published in 2023 4 reported a case of BRASH syndrome (bradycardia, renal failure, AV nodal blockade, shock, and hyperkalemia) in a patient taking metoprolol and diltiazem, highlighting the importance of early recognition of this syndrome.
• A study from 1990 5 discussed the pharmacologic management of ischemic heart disease with beta-blockers and calcium channel blockers, noting that beta-blockers reduce myocardial oxygen demand and have antiplatelet and antiarrhythmic effects.
• A 2014 study 6 compared the effect of calcium channel blockers and beta-blockers on exercise capacity and NT-proBNP levels in patients with permanent atrial fibrillation, finding that calcium channel blockers improved exercise capacity and reduced NT-proBNP levels compared to beta-blockers.

Key Findings

• Metoprolol can be effective in reducing mortality and hospitalization in patients with heart failure, but requires careful dosing and monitoring.
• Beta-blockers can cause bradycardia and other side effects, particularly when combined with other medications like calcium channel blockers.
• Calcium channel blockers may be more effective than beta-blockers in improving exercise capacity and reducing NT-proBNP levels in patients with atrial fibrillation.