Maximum Dose of Diltiazem for Atrial Fibrillation with RVR
The maximum recommended dose of intravenous diltiazem for acute rate control in atrial fibrillation with rapid ventricular response is 15 mg/hour as a continuous infusion, with bolus dosing not to exceed 0.35 mg/kg (typically 25 mg for average-weight patients). 1
Initial Bolus Dosing
- First bolus: Administer 0.25 mg/kg actual body weight IV over 2 minutes (20 mg is reasonable for average patients) 2, 1
- Second bolus (if inadequate response after 15 minutes): Administer 0.35 mg/kg actual body weight IV over 2 minutes (25 mg is reasonable for average patients) 1
- Onset of action occurs within 2-7 minutes after IV administration 2, 3
Continuous Infusion Maximum Dose
- Initial infusion rate: Start at 10 mg/hour immediately following bolus administration 1
- Some patients may maintain response at 5 mg/hour 1
- Maximum infusion rate: 15 mg/hour 2, 1
- The infusion may be increased in 5 mg/hour increments as needed for further heart rate reduction 1
- Maximum duration: 24 hours 1
- Critical limitation: Infusion rates exceeding 15 mg/hour and duration exceeding 24 hours have not been studied and are not recommended 1
Oral Maintenance Maximum Dose
Absolute Contraindications (Do Not Use Diltiazem)
- Heart failure with reduced ejection fraction (LVEF ≤40%) 2, 3
- Pre-excited atrial fibrillation (WPW syndrome with accessory pathway conduction) - may accelerate ventricular response and cause ventricular fibrillation 2, 3
- Severe hypotension 3
- Second or third-degree AV block without pacemaker 3
- Decompensated heart failure 2
Critical Monitoring Parameters
- Target heart rate: 60-80 bpm at rest or >20% reduction from baseline 2, 3
- Monitor blood pressure continuously during administration 3
- Watch for hypotension (occurs in 18-42% depending on dose) 3, 4
- Monitor for bradycardia and heart block 3
Important Clinical Pearls
- Lower doses may be equally effective with less hypotension: Research shows that doses ≤0.2 mg/kg achieve similar rate control (70.5% success) compared to standard doses (77.1% success) but with significantly lower hypotension rates (18% vs 34.9%) 4
- Diltiazem carries a Class I recommendation with Level of Evidence B for acute rate control in atrial fibrillation 3
- Avoid combining with beta-blockers due to risk of profound bradycardia from overlapping AV nodal blockade 2
- In patients with heart failure, use digoxin or amiodarone instead 3
- The half-life of IV diltiazem is 3-5 hours 3