Patient with cardiac history and tachycardia (140 bpm) not on any medications—should I start metoprolol (beta‑blocker)?

Should I Start Metoprolol for This Patient?

Yes, initiate metoprolol immediately for this patient with tachycardia (140 bpm) and cardiac history who is not on any medications—beta-blockade is guideline-directed therapy for rate control in tachyarrhythmias and provides cardiovascular protection in patients with cardiac disease. 1

Immediate Assessment Before First Dose

Before administering metoprolol, you must exclude absolute contraindications:

• Second- or third-degree AV block without a pacemaker 2
• Decompensated heart failure or cardiogenic shock (look for hypotension, pulmonary edema, elevated JVP) 2
• Severe bradycardia (though this patient has tachycardia) 2
• Severe obstructive airway disease with active bronchospasm (metoprolol is relatively beta-1 selective, so it may be used cautiously in bronchospastic disease if no alternatives exist) 2
• Systolic blood pressure <90 mmHg 3

Check a 12-lead ECG to identify the rhythm (atrial fibrillation, atrial flutter, sinus tachycardia, or supraventricular tachycardia) and assess for conduction abnormalities. 1

Initial Dosing Strategy

For Acute Rate Control (Intravenous Route)

If the patient is symptomatic (chest pain, dyspnea, hypotension) or requires rapid rate control:

• Administer metoprolol 2.5–5 mg IV over 2 minutes 1, 4
• Repeat every 5 minutes as needed, up to a total of 15 mg 4
• Monitor heart rate and blood pressure after each dose—target ventricular rate of 60–100 bpm at rest 1
• In clinical trials, IV metoprolol reduced ventricular rate from 134 to 106 bpm within 10 minutes in 81% of patients with supraventricular tachyarrhythmias 4

Caution: Hypotension occurred in 31% of patients receiving IV metoprolol but was transient and manageable 4. Hold the dose if systolic BP drops below 90 mmHg or heart rate falls below 50 bpm. 3

For Oral Initiation (Stable Patient)

If the patient is hemodynamically stable without acute symptoms:

• Start metoprolol tartrate 25–50 mg orally twice daily 1, 2
• Alternatively, use metoprolol succinate 50 mg once daily (extended-release formulation) 5
• Reassess heart rate and blood pressure 1–2 hours after the first dose 3
• Titrate every 1–2 weeks based on response, targeting resting heart rate of 60–80 bpm 1
• Maximum dose: metoprolol tartrate 200 mg twice daily or metoprolol succinate 400 mg once daily 5, 3

In a study of multifocal atrial tachycardia, oral metoprolol 25–50 mg restored sinus rhythm in all 11 patients within 1–3 hours, reducing mean ventricular rate from 131 to 87 bpm. 6

Specific Considerations Based on Cardiac History

If the Patient Has Coronary Artery Disease

• Metoprolol is strongly indicated for secondary prevention after myocardial infarction and reduces mortality 2
• Never abruptly discontinue metoprolol in these patients—severe exacerbation of angina, MI, and ventricular arrhythmias have been reported 2
• If discontinuation is necessary, taper gradually over 1–2 weeks 2

If the Patient Has Heart Failure

• Metoprolol succinate is guideline-directed medical therapy for heart failure with reduced ejection fraction 5
• Start at a low dose (metoprolol succinate 12.5–25 mg once daily) and titrate slowly to avoid precipitating acute decompensation 2
• Target dose: metoprolol succinate 200 mg once daily 5
• Monitor closely for signs of worsening heart failure (increased dyspnea, edema, weight gain) 2

If the Patient Has Atrial Fibrillation or Flutter

• Metoprolol is first-line therapy for rate control 1
• Guideline-recommended target is ventricular rate <100 bpm at rest and 90–115 bpm during moderate exercise 1
• In atrial fibrillation, IV metoprolol reduced ventricular rate by >15% in 82% of patients 4
• Consider adding digoxin if rate control is inadequate with metoprolol alone, especially if the patient has heart failure 1

Critical Safety Monitoring

After Initiating Therapy

• Measure heart rate and blood pressure 1–2 hours after the first dose 3
• Watch for excessive beta-blockade: dizziness, marked fatigue, heart rate <50 bpm, systolic BP <90 mmHg, new dyspnea or wheezing 3
• If severe bradycardia develops, reduce or stop metoprolol 2

Special Populations

Diabetes: Metoprolol may mask tachycardia and tremor associated with hypoglycemia, though dizziness and sweating are usually preserved 2. Advise the patient to monitor glucose more frequently and rely on non-adrenergic warning signs. 3

Thyrotoxicosis: Metoprolol may mask tachycardia from hyperthyroidism 2. If thyrotoxicosis is suspected (weight loss, heat intolerance, tremor), check TSH before attributing tachycardia solely to cardiac disease.

Bronchospastic disease: Because metoprolol is relatively beta-1 selective, it may be used cautiously in patients with COPD or asthma who have no alternative 2. Use the lowest effective dose, consider dividing into three times daily dosing to avoid peak plasma levels, and ensure bronchodilators are readily available. 2

Drug Interactions to Avoid

• Do not combine metoprolol with non-dihydropyridine calcium channel blockers (diltiazem, verapamil) due to markedly increased risk of severe bradycardia and heart block 1, 3
• Metoprolol is contraindicated with dofetilide (antiarrhythmic) 3
• CYP2D6 inhibitors (fluoxetine, paroxetine, quinidine) can increase metoprolol levels and enhance beta-blockade 3

When Metoprolol Fails or Is Insufficient

If heart rate remains >100 bpm despite optimal metoprolol dosing:

• Add low-dose digoxin (0.125–0.25 mg daily), particularly if the patient has heart failure or atrial fibrillation 1
• Consider ivabradine if sinus tachycardia persists and metoprolol causes intolerable side effects (hypotension, fatigue)—ivabradine reduced daytime heart rate more effectively than metoprolol (87 vs 95 bpm) in inappropriate sinus tachycardia 7
• AV node ablation with pacemaker implantation is reserved for refractory cases when pharmacologic therapy fails 1

Common Pitfalls to Avoid

• Do not withhold metoprolol in stable patients with mild heart failure—beta-blockers improve outcomes when initiated at low doses and titrated carefully 2
• Do not use atenolol as an alternative—it is less effective for blood pressure control and lacks proven benefit for anxiety or other non-hypertensive indications 3
• Do not abruptly stop metoprolol, especially in patients with coronary disease—taper over 1–2 weeks to prevent rebound hypertension, tachycardia, or angina 2, 3
• Do not assume all tachycardia is benign—obtain an ECG to rule out atrial fibrillation, flutter, or other arrhythmias requiring specific management 1