Parameters for Holding Metoprolol
Metoprolol should be held when patients present with heart rate <45 beats/min, second- or third-degree heart block, significant first-degree heart block (PR interval ≥0.24 sec), systolic blood pressure <100 mmHg, or signs of moderate-to-severe cardiac failure. 1, 2
Absolute Contraindications for Metoprolol
- Heart rate <45 beats/min 1
- Second- and third-degree heart block 1, 2
- Significant first-degree heart block (PR interval ≥0.24 seconds) 1, 2
- Systolic blood pressure <100 mmHg 1
- Moderate-to-severe cardiac failure or signs of worsening heart failure 1, 2
- Active asthma or reactive airways disease 2, 3
- Cardiogenic shock or increased risk for cardiogenic shock 3
- Hypersensitivity to metoprolol or other beta-blockers 1
Relative Contraindications and Caution Scenarios
- Patients with a low-output state (e.g., oliguria) 2
- Sinus tachycardia (often reflects low stroke volume) 2
- Significant sinus bradycardia (heart rate <50 beats/min) 2
- Hypotension (systolic blood pressure <90 mm Hg) 2
- Chronic obstructive pulmonary disease with reactive airway component 2
- Severe hepatic impairment (requires lower doses and careful titration) 1
Special Considerations for Specific Patient Populations
Heart Failure Patients
- In patients admitted for worsening heart failure, metoprolol dose may need to be reduced 2
- In severe situations, temporary discontinuation can be considered 2
- Low-dose therapy should be reinstituted and up-titrated once the patient's clinical condition improves, preferably before discharge 2
Perioperative Patients
- For patients undergoing non-cardiac surgery, metoprolol should be held if heart rate is consistently below 45 bpm or systolic blood pressure drops below 100 mmHg 2
- If heart rate is 45-49 bpm with systolic blood pressure >100 mmHg, delay the next dose for 12 hours 2
- Patients with tachycardia or in Killip Class II or III are at highest risk for cardiogenic shock with IV beta blockade 2
Patients with Pulmonary Disease
- For patients with mild wheezing or history of COPD, use a reduced dose of a cardioselective agent (e.g., 12.5 mg of metoprolol) rather than complete avoidance 2
- Start with low doses of a beta-1-selective agent and titrate cautiously 2
Monitoring Parameters During Metoprolol Therapy
- Blood pressure and heart rate should be checked before each administration 2, 3
- Target resting heart rate is 50-60 beats per minute unless limiting side effects occur 2, 3
- Monitor for signs of worsening heart failure (rales, S3 gallop) 2
- Continuous ECG monitoring during intravenous administration 2
- Auscultation for rales and bronchospasm 2
Resuming Metoprolol After Holding
- When resuming therapy after holding for hypotension or bradycardia, start at a lower dose and titrate gradually 2
- For patients with heart failure, low-dose therapy should be reinstituted and up-titrated as soon as clinical condition permits 2
- Avoid abrupt cessation of therapy to prevent rebound hypertension or worsening of angina 3
Common Pitfalls and Caveats
- Never abruptly discontinue metoprolol as it may induce rebound hypertension or worsening angina 2, 3
- For patients with heart failure, beta-blockers are strongly recommended before discharge even if temporarily held during acute decompensation 2
- Metoprolol blood levels are likely to increase substantially in patients with hepatic impairment, requiring lower initial doses 1
- Patients at highest risk for adverse events are those with tachycardia or in Killip Class II or III 2
- When initiating therapy in elderly patients, use lower starting doses due to greater frequency of decreased hepatic, renal, or cardiac function 1