For a hemodynamically stable patient with a ventricular rate of 140 beats per minute and no contraindications to beta‑blockers, what is the recommended initial metoprolol dosing and rate‑control strategy?

Metoprolol Dosing for Heart Rate of 140 bpm

For a hemodynamically stable patient with a heart rate in the 140s and no contraindications, administer metoprolol 5 mg IV push over 1–2 minutes, repeated every 5 minutes as needed up to a maximum total dose of 15 mg (three 5 mg boluses), targeting a heart rate below 100 bpm. 1, 2

Critical Pre-Administration Safety Checklist

Before giving any metoprolol, you must verify the absence of these absolute contraindications:

• Hemodynamic instability: Signs of heart failure, low cardiac output, decompensated heart failure, or cardiogenic shock 3, 1, 2
• Blood pressure: Systolic BP <100–120 mmHg with symptoms 1, 2
• Heart rate extremes: Baseline HR >110 bpm or <60 bpm 1, 2
• Conduction disease: PR interval >0.24 seconds, second- or third-degree AV block without a functioning pacemaker 3, 1, 2
• Respiratory disease: Active asthma or severe reactive airway disease 3, 1, 2
• Pre-excitation: Wolff-Parkinson-White syndrome or other accessory pathway syndromes 3, 2, 4

IV Dosing Protocol

Initial dose: 5 mg metoprolol tartrate IV push administered slowly over 1–2 minutes 1, 2

Repeat dosing: Additional 5 mg boluses every 5 minutes if heart rate remains elevated and blood pressure is stable 1, 2

Maximum total dose: 15 mg (three 5 mg boluses) in a single encounter 1, 2

Target heart rate: <100 bpm for lenient control; <80 bpm for strict control 3, 2

Required Monitoring During Administration

After each bolus, you must:

• Record systolic blood pressure and heart rate 1, 2
• Auscultate lungs for new rales (pulmonary congestion) 1
• Listen for bronchospasm 3, 1
• Maintain continuous telemetry to detect symptomatic bradycardia or hypotension 2

Transition to Oral Therapy

Wait 15 minutes after the final IV dose before starting oral metoprolol 1

Initial oral regimen: Metoprolol tartrate 25–50 mg every 6 hours for the first 48 hours 1

Maintenance dosing: Transition to metoprolol tartrate 50–100 mg twice daily (maximum 200 mg twice daily) or metoprolol succinate 50–200 mg once daily 3, 1

Alternative Agent for High-Risk Patients

If the patient has risk factors for adverse effects (age >70, systolic BP <120 mmHg, Killip class II–III), consider esmolol instead: 1, 2

• Loading dose: 500 mcg/kg IV over 1 minute 1, 2
• Maintenance infusion: 50–300 mcg/kg/min 1, 2
• Advantage: Ultra-short half-life (10–30 minutes) allows rapid titration and immediate reversibility 1, 2

Common Pitfalls to Avoid

Never administer the full 15 mg as a single rapid bolus – this dramatically increases the risk of hypotension and bradycardia 1, 2

Do not use metoprolol in pre-excited atrial fibrillation (WPW) – beta-blockade can paradoxically accelerate ventricular response via the accessory pathway and precipitate ventricular fibrillation 3, 2, 4

Do not give IV metoprolol to patients with decompensated heart failure – this can precipitate hemodynamic collapse 3, 1, 2

Do not assume adequate resting heart rate equals adequate overall rate control – always assess during activity 4

Context-Specific Considerations

If Atrial Fibrillation with RVR

Diltiazem may achieve rate control faster than metoprolol (95.8% vs 46.4% at 30 minutes), though both are safe and effective 5, 6. However, diltiazem is contraindicated in decompensated heart failure (Class III Harm) 3, 2, 4. Beta-blockers remain first-line in patients with heart failure or cardiomyopathy 4.

If Heart Failure or Cardiomyopathy

Beta-blockers are superior to calcium channel blockers for rate control in this population, achieving the rate-control endpoint in 70% vs 54% of patients 4. Nondihydropyridine calcium channel blockers (verapamil, diltiazem) should be avoided in systolic dysfunction 4.

If Inadequate Response to IV Metoprolol

Add digoxin as second-line therapy (Class IIa) – the combination controls heart rate both at rest and during exercise more effectively than either agent alone 4. Start digoxin 0.125–0.25 mg once daily without a loading dose 4.

Expected Adverse Event Rates

Approximately 27% of patients develop hypotension (systolic BP <90 mmHg) and 16% develop bradycardia (HR <40 bpm) during the first 24 hours of IV metoprolol therapy 1. Early IV metoprolol increases cardiogenic shock risk by approximately 11 per 1,000 treated patients, particularly in high-risk populations 1.