What are the parameters to hold metoprolol (beta-blocker)?

Parameters to Hold Metoprolol

Metoprolol should be held if the patient has a heart rate less than 50 beats per minute, systolic blood pressure less than 90 mmHg, signs of cardiogenic shock, or decompensated heart failure. 1, 2

Hemodynamic Parameters for Holding Metoprolol

• Heart Rate Parameters:

  • Hold if heart rate is less than 50 beats per minute 1
  • For IV metoprolol: discontinue infusion if heart rate drops below 50 bpm 1

• Blood Pressure Parameters:

  • Hold if systolic blood pressure is less than 90 mmHg 1
  • For IV metoprolol: discontinue if systolic blood pressure drops below 100 mmHg 1

• Signs of Low Cardiac Output:

  • Evidence of a low-output state (e.g., oliguria) 1
  • Sinus tachycardia reflecting low stroke volume 1

Cardiac Conduction Abnormalities

• Hold metoprolol in patients with:
  • Marked first-degree AV block (PR interval >0.24 seconds) 1
  • Any form of second-degree or third-degree AV block without a functioning pacemaker 1, 2

Heart Failure and Shock Considerations

• Hold in patients with:

  • Severe left ventricular dysfunction or heart failure (e.g., rales or S3 gallop) 1
  • Cardiogenic shock or high risk for shock 1
  • Decompensated heart failure requiring IV inotropic therapy 2

• Monitoring during withdrawal:

  • If metoprolol needs to be discontinued in patients with coronary artery disease, gradually reduce over 1-2 weeks to prevent severe exacerbation of angina, myocardial infarction, or ventricular arrhythmias 2

Respiratory Considerations

• Hold or use with extreme caution in:
  • History of asthma or severe reactive airway disease 1, 2
  • Significant chronic obstructive pulmonary disease with reactive airway component 1
  • Acute bronchospasm 2

Special Clinical Scenarios

• Perioperative Setting:

  • In perioperative patients, hold if heart rate is consistently below 45 bpm or systolic blood pressure is below 100 mmHg 1
  • If heart rate is 45-49 bpm, delay administration by 12 hours 1

• Acute Coronary Syndrome:

  • Hold in patients with tachycardia or in Killip Class II or III due to increased risk of cardiogenic shock 1
  • Patients at highest risk for cardiogenic shock due to IV beta blockade are those with tachycardia or in Killip Class II or III 1

• Aortic Dissection Management:

  • In patients with potential intolerance to beta-blockers (bronchial asthma, bradycardia, signs of heart failure), consider short-acting agents like esmolol first 1

Monitoring Recommendations

• During IV beta-blocker therapy, frequent checks of heart rate and blood pressure, continuous ECG monitoring, and auscultation for rales and bronchospasm are essential 1

• For patients on chronic therapy, monitor for:

  • Signs of worsening heart failure
  • Bradycardia requiring treatment (risk ratio 2.34) 1
  • Hypotension (risk ratio 1.29) 1

Important Caveats

• Beta-blocker withdrawal can increase mortality risk significantly. If discontinuation is necessary in patients with coronary artery disease, taper gradually over 1-2 weeks 2

• For patients with persistent tachycardia, investigate alternative causes such as sepsis, hypovolemia, pulmonary embolism, or anemia before assuming it's safe to continue beta-blocker therapy 1

• In patients with mild wheezing or history of COPD, consider using a reduced dose (e.g., 12.5 mg of metoprolol) rather than complete avoidance 1

• When restarting after holding, begin with lower doses and titrate gradually to avoid hemodynamic compromise 2

Remember that the decision to hold metoprolol should be based on careful clinical assessment, as inappropriate discontinuation in patients with coronary artery disease can lead to significant adverse outcomes.