Diltiazem Dosing for Rapid Ventricular Response (RVR)
For acute RVR in atrial fibrillation, administer an initial IV bolus of 0.25 mg/kg (approximately 15-20 mg for average adults) over 2 minutes, though lower doses of 0.13-0.2 mg/kg may be equally effective with reduced hypotension risk. 1, 2
Acute IV Management
Initial Bolus Dosing
- Standard dose: 0.25 mg/kg IV over 2 minutes (approximately 15-20 mg for average adult) 1, 3
- Alternative low-dose approach: 0.13-0.2 mg/kg may achieve similar rate control with significantly lower hypotension rates (18% vs 35% with standard dosing) 2
- Recent evidence demonstrates that doses ≥0.13 mg/kg achieve heart rate <100 bpm in mean time of 169 minutes compared to 318 minutes with lower doses 4
Second Bolus (if needed)
- If inadequate response after 15 minutes, administer 0.35 mg/kg (approximately 25 mg) over 2 minutes 1
Continuous Infusion
- Start at 5-15 mg/hour after bolus for sustained rate control 5
- Median effective infusion rate is 10 mg/hour 5
- Continue infusion for 6-20 hours until transitioning to oral therapy 5
Transition to Oral Therapy
Timing and Dosing
- Administer first oral dose while patient remains on IV infusion 5
- Discontinue IV infusion 4 hours after first oral dose 5
- Oral dosing: Extended-release formulations 180-360 mg once daily 6, 5
- Median effective oral dose is 300 mg/day 5
- 77% of patients maintain rate control during transition from IV to oral therapy 5
Long-term Maintenance
- Usual maintenance range: 120-360 mg daily of extended-release formulation 7, 6
- For chronic rate control in atrial fibrillation, doses of 240-360 mg daily are typically required 6
Critical Contraindications
Absolute contraindications include: 6, 1
- Second or third-degree AV block without functioning pacemaker
- Sick sinus syndrome without pacemaker
- Wolff-Parkinson-White syndrome with atrial fibrillation/flutter (risk of accelerated conduction down accessory pathway)
- Decompensated systolic heart failure or severe LV dysfunction
- Cardiogenic shock
- Hypotension (SBP <90 mmHg)
Important Safety Considerations
Drug Interactions
- Avoid routine combination with beta-blockers due to increased risk of profound bradycardia, AV block, and heart failure 7, 6
- Diltiazem is a moderate CYP3A4 inhibitor: doses >120 mg/day significantly increase bleeding risk when combined with apixaban or rivaroxaban (HR 1.29 for serious bleeding) 8
- Consider dose reduction of apixaban/rivaroxaban or use metoprolol as alternative rate-control agent in anticoagulated patients 8
Monitoring Requirements
- Blood pressure and heart rate before and after each bolus 6
- Continuous cardiac monitoring during IV administration 1
- ECG monitoring in patients with conduction system disease 6
- Have resuscitation equipment immediately available 1
Common Adverse Effects
- Hypotension is most common (18-42% depending on dose), especially with IV administration 2, 4
- Bradycardia occurs but rarely requires discontinuation 4
- Peripheral edema with chronic oral therapy (dose-related, more common in women) 7
Clinical Pearls
- Lower initial doses (0.13-0.2 mg/kg) reduce hypotension risk without sacrificing efficacy in most patients 2, 4
- Diltiazem works by slowing AV nodal conduction and increasing refractoriness 1
- In hemodynamically unstable patients, synchronized cardioversion is preferred over medication 1
- For patients with pre-existing ventricular dysfunction, consider alternative agents as diltiazem may worsen heart failure 6, 1
- Asymptomatic low blood pressure (e.g., 115/60 mmHg) does not require dose adjustment when heart rate control is the primary goal 6