When should metoprolol (beta-blocker) be held?

When to Hold Metoprolol

Metoprolol should be held when patients develop signs of cardiogenic shock, severe bradycardia (heart rate <50 bpm with symptoms or <45 bpm), symptomatic hypotension (systolic BP <100 mmHg with symptoms), or require inotropic support. 1, 2

Critical Situations Requiring Immediate Discontinuation

Cardiogenic Shock and Severe Heart Failure

• Hold metoprolol immediately if cardiogenic shock develops or if inotropic support is needed 1, 2
• Patients with acute heart failure (AHF) presenting with more than basal pulmonary rales should have beta-blockers used cautiously or held 1
• The COMMIT trial demonstrated an excess of 11 cardiogenic shock cases per 1000 patients treated with early IV metoprolol, particularly during days 0-1 after acute MI 1, 3

Severe Bradycardia

• Hold metoprolol if heart rate falls below 50 bpm with worsening symptoms 1
• Stop immediately if heart rate is consistently below 45 bpm 1
• Patients with heart rate 45-49 bpm and systolic BP >100 mmHg should delay the dose by 12 hours 1
• Evaluate for heart block with ECG if bradycardia develops 1

Symptomatic Hypotension

• Hold if systolic blood pressure drops below 100 mmHg with symptoms of dizziness, lightheadedness, or confusion 1, 2
• Asymptomatic low blood pressure alone does not require holding the medication 1
• Before each dose administration, verify heart rate ≥50 bpm and systolic BP ≥100 mmHg 1

High-Risk Clinical Scenarios

Perioperative Period

• The POISE trial showed increased mortality with high-dose metoprolol started on the day of surgery in beta-blocker-naïve patients 1
• Do not routinely withdraw chronically administered metoprolol before major surgery, but be prepared for impaired cardiac response to reflex adrenergic stimuli 2
• Routine administration of high-dose beta-blockers without dose titration on the day of surgery is harmful and should not be done 1

Acute Myocardial Infarction - First 24 Hours

• Hold in patients with systolic BP <120 mmHg, heart rate >110 bpm, age >70 years, or Killip class >1 (signs of heart failure) 1, 3
• The excess cardiogenic shock risk is highest during days 0-1 after MI admission 1, 3
• After hemodynamic stabilization (usually after day 1-2), metoprolol should be initiated or resumed 1, 3

Dose Reduction Rather Than Complete Holding

Worsening Heart Failure Symptoms

• If increasing congestion develops, first increase diuretic dose; if ineffective, halve the metoprolol dose rather than stopping completely 1
• For marked fatigue, halve the dose and reassess in 1-2 weeks 1
• Beta-blockers should not be stopped suddenly unless absolutely necessary due to risk of rebound myocardial ischemia, infarction, or arrhythmias 1, 2

Conduction Abnormalities

• Patients with first-degree AV block, sinus node dysfunction, or conduction disorders are at increased risk and require careful monitoring 2
• Consider dose reduction if PR interval >0.24 seconds or if second or third-degree heart block develops 4

Special Populations and Conditions

Bronchospastic Disease

• While not an absolute contraindication in beta-1 selective metoprolol, hold if severe bronchospasm develops 2
• Use lowest possible dose and consider three times daily dosing instead of twice daily to avoid higher peak plasma levels 2

Pheochromocytoma

• Metoprolol should only be given after alpha-blocker initiation; never use beta-blockers alone in this setting 2

Thyrotoxicosis

• Avoid abrupt withdrawal as it might precipitate thyroid storm, but metoprolol may mask tachycardia of hyperthyroidism 2

Concurrent Beta-Blocker Use

• Do not administer as-needed labetalol to patients already on oral metoprolol due to risk of excessive beta-blockade causing bradycardia, hypotension, or cardiogenic shock 4
• If transitioning between beta-blockers, gradually taper the first before initiating the second 4

Practical Monitoring Parameters

When continuing metoprolol therapy, hold the next dose if:

• Heart rate <50 bpm with symptoms or <45 bpm regardless of symptoms 1
• Systolic blood pressure <100 mmHg with symptoms 1
• Signs of pulmonary edema or cardiogenic shock develop 1, 2
• Patient requires inotropic support 1

The key principle is that metoprolol should be held for hemodynamic instability but continued whenever safely possible given the long-term mortality benefits in heart failure and post-MI patients. 1, 5