In a patient taking metoprolol succinate 25 mg twice daily for arrhythmia who develops severe symptomatic bradycardia, what is the appropriate management?

Management of Severe Bradycardia in a Patient on Metoprolol Succinate

Stop metoprolol immediately and do not give the next dose—severe symptomatic bradycardia is an absolute contraindication to continued beta-blocker therapy. 1, 2

Immediate Assessment

When a patient on metoprolol develops severe bradycardia, you must first determine whether the bradycardia is truly symptomatic:

• Check for signs of instability: acute altered mental status, ischemic chest discomfort, acute heart failure, hypotension, dizziness, lightheadedness, syncope, or other signs of shock 3, 1
• Measure vital signs: document heart rate and blood pressure; symptomatic bradycardia is typically defined as HR <50-60 bpm with symptoms 1
• Obtain a 12-lead ECG to identify the rhythm and rule out high-grade AV block (second or third-degree) 1
• Ensure adequate oxygenation and establish IV access 1
• Rule out other causes: infection, hypothyroidism, increased intracranial pressure, or other medications causing bradycardia (digoxin, diltiazem, verapamil, amiodarone) 1

Acute Pharmacological Management

If the patient remains symptomatic after holding metoprolol:

• Administer atropine 0.5 mg IV every 3-5 minutes up to a maximum total dose of 3 mg 3, 1
• If atropine fails, initiate transcutaneous pacing or start an IV infusion of dopamine or epinephrine with rate-accelerating effects 3, 1
• Prepare for emergent transvenous temporary pacing if the patient does not respond to atropine or transcutaneous pacing 3

Critical Warning About Abrupt Discontinuation

Never abruptly discontinue metoprolol in patients with underlying coronary artery disease or heart failure. 1, 2 The FDA label warns that abrupt cessation can cause severe exacerbation of angina, myocardial infarction, and ventricular arrhythmias, with one study showing 50% mortality after abrupt withdrawal 1. Beta-blocker withdrawal is associated with a 2.7-fold increased risk of 1-year mortality compared to continuous use 1.

Dose Reduction Strategy (Once Stabilized)

If the patient has underlying coronary disease or heart failure and stabilizes after acute management:

• Reduce metoprolol dose by 50% rather than completely discontinuing it 1
• For a patient on 25 mg twice daily, reduce to 12.5 mg twice daily or 12.5 mg once daily 1
• Hold the dose completely only if: systolic blood pressure remains <100 mmHg with symptoms, heart rate remains <45 bpm consistently, or signs of decompensated heart failure develop 1

Monitoring Protocol After Dose Adjustment

• Monitor heart rate, blood pressure, and symptoms within 1-2 weeks after reducing metoprolol 1
• Watch specifically for: worsening heart failure symptoms (increased dyspnea, fatigue, edema, weight gain), recurrent angina, or new arrhythmias 1
• Heart rate should improve within days to 1-2 weeks with appropriate dose reduction 1

Common Pitfalls to Avoid

• Do not assume the bradycardia is benign—always assess for symptoms and hemodynamic compromise 1
• Do not completely stop metoprolol abruptly in patients with coronary disease or heart failure without a tapering plan 1, 2
• Do not restart at the same dose that caused symptomatic bradycardia; if restarting is necessary, use the lowest possible dose (12.5 mg once daily) and titrate slowly 1
• Do not overlook drug interactions—check for other rate-lowering medications that may be contributing 1

When to Seek Specialist Consultation

If symptoms don't improve with dose reduction or if the patient requires complete discontinuation of beta-blockade despite having heart failure or recent myocardial infarction, seek cardiology consultation for alternative management strategies 1.