From the Guidelines
Metoprolol is not absolutely contraindicated in patients with first-degree AV block, but caution is advised as it may worsen conduction 1.
Important Considerations
- In patients with first-degree AV block, metoprolol should be initiated at a low dose, such as 25-50mg daily, and titrated gradually as needed and tolerated, with close monitoring of heart rate and rhythm.
- The use of metoprolol in this population requires careful consideration of the potential benefits and risks, and alternative beta blockers with less negative chronotropic effect, such as atenolol or bisoprolol, may be preferred in certain cases.
Key Points to Consider
- Patients with marked first-degree AV block (i.e., ECG PR interval greater than 0.24 s) should not receive beta blockers on an acute basis 1.
- Beta blockers without intrinsic sympathomimetic activity are preferred, and metoprolol is a relatively selective beta-1 blocker 1.
- The choice of beta blocker for an individual patient is based primarily on pharmacokinetic and side effect criteria, as well as on physician familiarity 1.
Monitoring and Dosing
- Monitoring during intravenous beta-blocker therapy should include frequent checks of heart rate and blood pressure and continuous ECG monitoring, as well as auscultation for rales and bronchospasm 1.
- Intravenous metoprolol may be given in 5-mg increments by slow intravenous administration (5 mg over 1 to 2 min), repeated every 5 min for a total initial dose of 15 mg 1.
From the FDA Drug Label
CONTRAINDICATIONS ... significant first-degree heart block (P-R interval ≥ 0.24 sec); Bradycardia, including sinus pause, heart block, and cardiac arrest have occurred with the use of metoprolol. Patients with first-degree atrioventricular block, sinus node dysfunction, or conduction disorders may be at increased risk.
Metoprolol is contraindicated in patients with significant first-degree heart block (P-R interval ≥ 0.24 sec), but it is not contraindicated in all cases of first-degree AV block. The decision to use metoprolol in patients with first-degree AV block should be made with caution and careful monitoring of heart rate and rhythm 2, 2.
From the Research
Metoprolol Contraindication in First-Degree Atrioventricular (AV) Block
- There are no direct research papers provided that discuss the contraindication of metoprolol in first-degree Atrioventricular (AV) block.
- The provided studies focus on the clinical manifestations, indications for pacing, pacemaker management, and consequences during cardiac resynchronization in patients with first-degree AV block 3, 4, 5, 6, 7.
- None of the studies mention metoprolol or its contraindication in first-degree AV block, suggesting that the available evidence does not directly address this question.
- The studies do discuss the potential risks and complications associated with first-degree AV block, such as an increased risk of atrial fibrillation, heart failure, and pacemaker implantation 3, 4, 5, 6.
- However, without specific information on metoprolol, it is not possible to determine its contraindication in first-degree AV block based on the provided evidence.