Do you initiate oral rate control medications prior to discontinuing intravenous (IV) diltiazem (calcium channel blocker) therapy?

From the Guidelines

Yes, oral rate control medications should be initiated prior to discontinuing intravenous (IV) diltiazem (calcium channel blocker) therapy.

Rationale

• The ACC/AHA/ESC 2006 guidelines 1 recommend measuring the heart rate at rest and controlling the rate using pharmacological agents, such as beta blockers or non-dihydropyridine calcium channel antagonists, for patients with persistent or permanent atrial fibrillation (AF).
• The guidelines also recommend intravenous administration of beta blockers or non-dihydropyridine calcium channel antagonists, such as diltiazem, to slow the ventricular response to AF in the acute setting, exercising caution in patients with hypotension or heart failure (HF) 1.
• When transitioning from IV to oral therapy, it is essential to initiate oral rate control medications, such as metoprolol, propranolol, or diltiazem, to maintain adequate heart rate control 1.
• The 2011 ACCF/AHA/HRS focused updates 1 also support the use of oral rate control medications, such as beta blockers or non-dihydropyridine calcium channel antagonists, to control the heart rate in patients with AF.

Key Points

• Diltiazem can be administered orally at a dose of 120 to 360 mg daily in divided doses, with a slow-release formulation available 1.
• Metoprolol can be administered orally at a dose of 25 to 100 mg twice a day 1.
• Propranolol can be administered orally at a dose of 80 to 240 mg daily in divided doses 1.
• It is crucial to assess the adequacy of heart rate control during physical activity and adjust pharmacological treatment as necessary to keep the rate in the physiological range 1.

From the Research

Initiation of Oral Rate Control Medications

When transitioning from intravenous (IV) diltiazem to oral diltiazem, the initiation of oral rate control medications is a crucial step.

• The study 2 found that oral long-acting diltiazem was 77% effective in controlling ventricular response over 48 hours in patients with atrial fibrillation (AF) or atrial flutter (AFl) in whom ventricular response was initially controlled with IV diltiazem.
• In this study, IV diltiazem infusion was discontinued 4 hours after the first oral dose, and patients were monitored during 48 subsequent hours of "transition" to oral therapy.

Comparison of Oral and IV Diltiazem

The effectiveness of oral versus IV diltiazem for acute heart rate control has been compared in several studies.

• A study 3 found that oral immediate-release diltiazem was associated with a lower rate of treatment failure at four hours than IV continuous infusion in patients with AF with rapid ventricular response (RVR).
• The median dose of oral diltiazem and IV continuous infusion diltiazem at four hours was 30 mg and 10 mg/h, respectively.

Transitioning from IV to Oral Diltiazem

When transitioning from IV to oral diltiazem, it is essential to consider the timing and dosage of oral medications.

• The study 2 suggests that oral long-acting diltiazem can be initiated while the patient is still receiving IV diltiazem, and the IV infusion can be discontinued 4 hours after the first oral dose.
• However, the optimal timing and dosage of oral medications may vary depending on individual patient factors and the specific clinical scenario.

Other Considerations

Other studies have compared the efficacy and safety of IV metoprolol and diltiazem for rate control in AF 4, and the use of calcium chloride before IV diltiazem in the management of AF 5.

• These studies provide additional insights into the management of AF and the use of different medications for rate control.