From the Guidelines
The initial dose of diltiazem for acute atrial fibrillation with rapid ventricular response is 0.25 mg/kg (typically 15-20 mg) administered as an intravenous bolus over 2 minutes, as recommended by the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1. This dose can be adjusted based on the patient's response, with a second bolus of 0.35 mg/kg (typically 20-25 mg) given if needed after 15 minutes. Following successful rate control, a continuous infusion is typically started at 5-15 mg/hour, titrated to maintain heart rate control. Before administration, blood pressure should be assessed as diltiazem can cause hypotension. The medication works by blocking calcium channels in the heart, which slows conduction through the AV node, thereby reducing ventricular rate in AFib. This helps improve cardiac output and reduces symptoms while decreasing myocardial oxygen demand. Some key points to consider when administering diltiazem include:
- Monitoring for hypotension, bradycardia, and heart block during administration
- Using caution in patients with heart failure, hypotension, or those taking other medications that affect cardiac conduction, such as beta-blockers
- Avoiding use in patients with pre-excited atrial fibrillation, as it may cause a paradoxical increase in ventricular response 1. It's also important to note that the choice of diltiazem for rate control in AFib is supported by guidelines from the American College of Cardiology, American Heart Association, and European Society of Cardiology 1. Overall, diltiazem is a effective and commonly used medication for rate control in acute atrial fibrillation with rapid ventricular response, and its use should be guided by the most recent and highest quality evidence available 1.
From the FDA Drug Label
The initial dose of diltiazem hydrochloride injection should be 0.25 mg/kg actual body weight as a bolus administered over 2 minutes (20 mg is a reasonable dose for the average patient).
The initial dose of diltiazem for acute atrial fibrillation (AFib) with rapid ventricular response (RVR) is 0.25 mg/kg actual body weight, which can be approximated to 20 mg for the average patient, administered over 2 minutes 2.
From the Research
Initial Dose of Diltiazem for Acute AFib with RVR
The initial dose of diltiazem for acute atrial fibrillation (AFib) with rapid ventricular response (RVR) is a crucial aspect of treatment. According to the studies, the recommended initial dose is:
- An intravenous bolus of 0.25 mg/kg over 2 minutes 3, 4
- A maximum dose of 20mg for stable, symptomatic patients in AFIB with RVR at a rate of >150 beats per minute (bpm) with a narrow complex 5
Comparison of Weight-Based Dose vs. Standard Dose
Some studies compared the efficacy and safety of weight-based dose vs. standard dose diltiazem:
- A study found that low-dose diltiazem (≤ 0.2 mg/kg) might be as effective as the standard dose in controlling rapid AF and reduce the risk of hypotension 3
- Another study found that standard dose diltiazem was noninferior to weight-based dosing in the initial treatment of AF with RVR 6
Safety and Efficacy
The safety and efficacy of diltiazem for AFib with RVR have been evaluated in several studies:
- A study found that intravenous diltiazem was rapidly effective for slowing the ventricular response in most patients with atrial fibrillation or atrial flutter, with a response rate of 94% 4
- Another study found that prehospital diltiazem administration for AFIB with RVR is safe and effective when strict protocols are followed, with a clinical improvement rate of 57% and an adverse event rate of 11% 5