Diltiazem Dosing for Rate Control in Atrial Fibrillation
For acute rate control in atrial fibrillation with rapid ventricular response, administer diltiazem 0.25 mg/kg IV bolus over 2 minutes, followed by a continuous infusion of 5-15 mg/hour titrated to heart rate response. 1, 2
Initial IV Bolus Dosing
- Administer 0.25 mg/kg IV over 2 minutes as the initial bolus dose 1, 2
- If inadequate response after 15 minutes, give a second bolus of 0.35 mg/kg 2
- Onset of action occurs within 2-7 minutes after IV administration 2
Alternative Lower-Dose Strategy
- Doses as low as ≤0.2 mg/kg (often 10 mg fixed dose) have demonstrated similar efficacy with significantly reduced hypotension risk 3
- Lower doses (≤0.2 mg/kg) achieved therapeutic response in 70.5% of patients compared to 77.1% with standard dosing (0.2-0.3 mg/kg), but with hypotension rates of only 18% vs. 34.9% 3
- However, doses ≥0.13 mg/kg achieved heart rate control faster (169 minutes vs. 318 minutes) and more frequently (61% vs. 36%) than lower doses 4
Continuous Infusion
- Start at 5-15 mg/hour immediately after the bolus 1, 2
- Titrate in 5 mg/hour increments up to 15 mg/hour maximum based on heart rate response 2
- Target heart rate: <100 bpm at rest or >20% reduction from baseline 2
Transition to Oral Therapy
- Initiate oral diltiazem once stable rate control is achieved for 15-30 minutes after IV bolus 2
- Immediate-release: Start 30-60 mg every 6 hours (120-240 mg/day total), titrate up to maximum 90 mg every 6 hours (360 mg/day) 2
- Extended-release: 180-360 mg once daily for maintenance after 24-48 hours of stable control 1, 2
Critical Contraindications (Must Exclude Before Administration)
- Heart failure with reduced ejection fraction (LVEF ≤40%) - use digoxin or amiodarone instead 1, 2
- Pre-excited atrial fibrillation (WPW syndrome with AF) - diltiazem can paradoxically increase ventricular rate 1, 2
- Second or third-degree AV block without pacemaker 1, 2
- Severe hypotension or cardiogenic shock 1, 2
- Decompensated systolic heart failure 1
Monitoring Requirements
- Continuous heart rate and blood pressure monitoring during and for 2-4 hours after administration 2
- Watch for hypotension (18-42% incidence), bradycardia (<50 bpm), and heart block 2
- Avoid combining with beta-blockers due to additive AV nodal blockade and negative inotropic effects 2
Clinical Pearls
- Diltiazem carries a Class I recommendation (Level of Evidence B) for acute rate control in atrial fibrillation, making it one of the most strongly supported agents 2
- The half-life is 3-5 hours for IV formulation, requiring continuous infusion for sustained effect 2
- Weight-based dosing (0.25 mg/kg) is superior to fixed 10 mg dosing for achieving rapid rate control, though lower doses may be safer in hypotension-prone patients 3, 4
- Diltiazem is more effective than metoprolol for rapid rate control, achieving target heart rate <100 bpm in 95.8% vs. 46.4% of patients at 30 minutes 5