Should intravenous (IV) metoprolol (Lopressor) or diltiazem (Cardizem) be administered to a patient experiencing sinus tachycardia with borderline hypotension?

From the Guidelines

For a patient with sinus tachycardia and borderline blood pressure, diltiazem is generally preferred over IV metoprolol.

Key Considerations

• Diltiazem (initial dose 0.25 mg/kg IV over 2 minutes, followed by 5-15 mg/hour infusion if needed) provides effective heart rate control with less risk of significant blood pressure reduction compared to metoprolol, as noted in the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1.
• This is particularly important in patients with already borderline blood pressure, as beta-blockers like metoprolol can cause more pronounced hypotension, potentially leading to adverse outcomes such as decreased perfusion of vital organs.
• Diltiazem works primarily by blocking calcium channels in the heart, slowing conduction through the AV node and reducing heart rate while causing less peripheral vasodilation than beta-blockers, which is beneficial in maintaining blood pressure.

Important Precautions

• The underlying cause of the sinus tachycardia should be identified and treated (such as pain, anxiety, hypovolemia, or infection) to address the root cause of the condition.
• Close monitoring of vital signs is essential during administration of either medication, with immediate access to vasopressors and cardiac monitoring equipment to quickly respond to any adverse effects.
• If the patient has certain conditions like heart failure with reduced ejection fraction or acute coronary syndrome, the risk-benefit assessment may change, potentially favoring cautious use of metoprolol despite the borderline blood pressure, as guided by the principles outlined in the 2015 ACC/AHA/HRS guideline 1.

Medication Administration

• When administering diltiazem, it is crucial to follow the recommended dosing regimen to minimize the risk of adverse effects such as hypotension, worsening heart failure, or bradycardia.
• Metoprolol, if chosen, should be administered with caution, starting with a low dose (2.5-5.0 mg IV bolus over 2 minutes) and titrating as needed, while closely monitoring blood pressure and heart rate, as per the guidelines 1.

From the FDA Drug Label

Injectable forms of diltiazem are contraindicated in: ... 3. Patients with severe hypotension or cardiogenic shock. Intravenous diltiazem and intravenous beta-blockers should not be administered together or in close proximity (within a few hours). The use of intravenous diltiazem for control of ventricular response in patients with supraventricular arrhythmias should be undertaken with caution when the patient is compromised hemodynamically.

The patient is experiencing sinus tachycardia with borderline blood pressure readings. Given the contraindications and warnings in the drug label, iv diltiazem should be used with caution due to the potential for hypotension. IV metoprolol and iv diltiazem should not be administered together or in close proximity. Considering the patient's borderline blood pressure readings, iv metoprolol may be a better option, but it is crucial to monitor the patient's blood pressure and cardiac function closely. However, without more information about the patient's condition, it is difficult to make a definitive decision. Key considerations:

• Monitor blood pressure and cardiac function closely
• Avoid administering iv diltiazem and iv metoprolol together or in close proximity
• Use iv diltiazem with caution in patients with borderline blood pressure readings 2 2

From the Research

Treatment Options for Sinus Tachycardia

• The decision to use IV metoprolol or diltiazem for treating sinus tachycardia with borderline blood pressure readings depends on various factors, including the patient's medical history and current condition.
• According to a study published in 2001 3, diltiazem was effective in achieving short-term control of heart rate in 56% of patients with sinus tachycardia, without significant adverse effects, where beta-blockade was contraindicated or ineffective.
• A systematic review and meta-analysis published in 2024 4 found that metoprolol was associated with a 26% lower risk of adverse events compared to diltiazem for treating atrial fibrillation with rapid ventricular rate.

Comparison of Metoprolol and Diltiazem

• A study published in 2021 5 compared the effectiveness and safety of metoprolol and diltiazem for rate control of supraventricular tachycardia in the emergency department, and found that the two medications had similar rates of achieving rate control, but diltiazem was associated with a higher incidence of hypotension.
• Another study published in 2023 6 found that metoprolol and diltiazem were equally effective in achieving rate control in patients with atrial fibrillation and heart failure with reduced ejection fraction, with no significant difference in safety outcomes.
• A study published in 2013 7 compared metoprolol succinate and ivabradine for treating inappropriate sinus tachycardia, and found that ivabradine was more effective in relieving symptoms during exercise or daily activity, but metoprolol and ivabradine had similar effects on resting heart rate.

Considerations for Treatment

• When deciding between IV metoprolol and diltiazem, healthcare providers should consider the patient's individual characteristics, medical history, and current condition, as well as the potential risks and benefits of each medication 4, 5, 6.
• The choice of medication may also depend on the specific clinical scenario, such as the presence of heart failure or other comorbidities 6.