What do I do once I reach a goal heart rate of 110 beats per minute (BPM) on Cardizem (diltiazem) at 15mg/hour?

Management After Reaching Goal Heart Rate of 110 BPM on Cardizem at 15mg/hr

Once you reach the goal heart rate of 110 BPM on Cardizem (diltiazem) at 15mg/hr, maintain this infusion rate while transitioning to oral therapy, as this represents successful rate control according to current guidelines. 1

Immediate Management

• Continue the current diltiazem infusion at 15mg/hr to maintain the achieved heart rate control
• Begin planning for transition to oral therapy, as IV diltiazem is not intended for long-term use (typically limited to 24 hours) 2
• Monitor vital signs every 15-30 minutes initially, then hourly once stable

Transition to Oral Therapy

Step 1: Initiate oral diltiazem

• Start oral long-acting diltiazem (diltiazem CD) 4 hours before discontinuing the IV infusion 3
• Typical starting dose is 180-300mg once daily 3
• For patients previously on 15mg/hr IV diltiazem, a dose of 300mg/day oral diltiazem CD is often appropriate 3

Step 2: Discontinue IV infusion

• Discontinue IV diltiazem 4 hours after the first oral dose 3
• Continue cardiac monitoring for at least 4 hours after discontinuation of IV therapy

Step 3: Monitor during transition

• Continue heart rate monitoring for 48 hours during transition to oral therapy 3
• Maintain the target heart rate of <110 BPM (lenient control) 1
• Consider stricter heart rate control only if symptoms persist 1

Long-term Management Considerations

For patients with preserved left ventricular function (LVEF >40%):

• Continue oral diltiazem, beta-blocker, or digoxin as appropriate 1
• Target resting heart rate <110 BPM (lenient control) 1

For patients with reduced left ventricular function (LVEF ≤40%):

• Consider switching to beta-blocker or digoxin for long-term management 1
• Avoid long-term diltiazem due to negative inotropic effects 1

Important Monitoring Parameters

• Blood pressure (watch for hypotension)
• Heart rate (target <110 BPM)
• ECG (monitor for AV block, especially if combined with beta-blockers) 4
• Symptoms of heart failure (if applicable)

Common Pitfalls to Avoid

1. Abrupt discontinuation: Never abruptly stop IV diltiazem without proper transition to oral therapy
2. Inadequate monitoring: Continue cardiac monitoring during transition period
3. Drug interactions: Use caution when combining diltiazem with beta-blockers due to risk of profound bradycardia or heart block 1, 4
4. Inappropriate long-term use: Avoid long-term diltiazem in patients with reduced ejection fraction (LVEF ≤40%) 1
5. Failure to adjust therapy: If heart rate control is inadequate after transition to oral therapy, consider dose adjustment or addition of another agent

Special Considerations

• If the patient has heart failure with reduced ejection fraction, consider transitioning to a beta-blocker rather than oral diltiazem for long-term management 1
• If the patient remains symptomatic despite adequate rate control, consider rhythm control strategies 1
• For patients with atrial fibrillation, assess stroke risk and need for anticoagulation 1

Remember that successful transition from IV to oral diltiazem occurs in approximately 77% of patients 3, so close monitoring during this period is essential to ensure continued heart rate control.