Metoprolol for Sinus Tachycardia
Yes, metoprolol can be given to an adult patient with sinus tachycardia who has no history of asthma, COPD, or heart failure, but only after identifying and treating the underlying cause of the tachycardia. 1
Critical First Step: Identify the Underlying Cause
Sinus tachycardia is a physiologic response, not a primary arrhythmia. Before administering metoprolol, you must address reversible causes:
- Hypoxia and respiratory distress must be corrected first 2
- Hypovolemia, sepsis, pain, anxiety, fever, or anemia should be treated as the primary intervention 3
- Low cardiac output states (oliguria, hypotension) are absolute contraindications to beta-blockers until resolved 3
Common pitfall: Treating sinus tachycardia with beta-blockers without addressing the underlying cause can mask important physiologic compensation and worsen outcomes 3, 1.
Absolute Contraindications to Metoprolol
Do not give metoprolol if any of the following are present:
- Active asthma (absolute contraindication) 3, 4, 5, 1
- Severe decompensated heart failure with rales, S3 gallop, or signs of cardiogenic shock 3, 4, 1
- Significant bradycardia (heart rate <50 bpm) 3, 4
- Hypotension (systolic BP <90 mmHg) 3, 4, 1
- Second- or third-degree AV block without a pacemaker 3, 4
- Evidence of low cardiac output (oliguria, altered mental status) 3, 4
When Metoprolol Is Appropriate for Sinus Tachycardia
Metoprolol is reasonable in specific clinical contexts where sinus tachycardia is contributing to myocardial ischemia or hemodynamic instability:
Acute Coronary Syndrome with Tachycardia
- Intravenous metoprolol may be warranted for ongoing rest pain with tachycardia or hypertension in hemodynamically stable patients 3, 4
- Oral metoprolol should be started early in unstable angina/NSTEMI in the absence of contraindications 3, 4
- Beta-blockers reduce myocardial oxygen demand by decreasing heart rate and contractility 3, 4
Post-Myocardial Infarction
- Beta-blockers are strongly recommended before discharge for secondary prevention, even in patients with compensated heart failure or LV dysfunction 3, 4
Special Populations
COPD Without Asthma
- Beta-1 selective agents like metoprolol are NOT contraindicated in COPD patients without active bronchospasm 3, 4, 5
- Start with low doses (e.g., 12.5 mg orally) and monitor for wheezing 3, 5, 1
- Ensure bronchodilators are readily available 1
Mild Wheezing or Reactive Airway Disease
- Use a short-acting cardioselective agent at reduced dose (12.5 mg metoprolol) rather than complete avoidance 3, 5
- Monitor respiratory function closely 5
- Alternative: Consider calcium channel blockers (diltiazem or verapamil) if bronchospasm is a concern 5, 2
Dosing Strategy
- Oral metoprolol: Start with 25-50 mg twice daily for most indications 3, 6, 7
- Intravenous metoprolol: 2.5-5 mg IV over 2 minutes, may repeat every 5 minutes up to 15 mg total for acute situations 7, 8
- Low-dose initiation: 12.5 mg orally for patients with mild respiratory disease or concerns about tolerance 3, 5, 1
Critical Safety Warning
Never abruptly discontinue metoprolol in patients with coronary artery disease—this can cause severe exacerbation of angina, myocardial infarction, and ventricular arrhythmias 4, 1. Taper over 1-2 weeks when discontinuation is necessary 1.
Monitoring After Administration
- Heart rate and rhythm: Watch for excessive bradycardia (<50 bpm) 3, 1
- Blood pressure: Monitor for hypotension 3, 1, 7
- Respiratory status: Assess for new or worsening wheezing, especially in patients with any pulmonary disease 5, 1
- Signs of heart failure: Watch for worsening dyspnea, rales, or peripheral edema 1
Alternative Agents
If metoprolol is contraindicated or not tolerated: