Should you hold Tikosyn (dofetilide) if heart rate is less than 60, specifically in cases of bradycardia?

Management of Tikosyn (Dofetilide) in Patients with Bradycardia

Yes, you should hold Tikosyn (dofetilide) if the heart rate is less than 60 beats per minute, as specifically stated in the FDA labeling. 1

Rationale for Holding Tikosyn in Bradycardia

• The FDA drug label explicitly states: "The QT interval should be used if the heart rate is <60 beats per minute. There are no data on use of TIKOSYN when the heart rate is <50 beats per minute." 1

• Bradycardia is listed as a potential adverse effect of dofetilide, which can further exacerbate a pre-existing slow heart rate 2

• Dofetilide is a Class III antiarrhythmic that prolongs the QT interval, and this effect becomes more pronounced and potentially dangerous at slower heart rates 3

Clinical Decision Algorithm

1. Assess heart rate:

   • If heart rate is <60 bpm: Hold Tikosyn and use QT interval (not QTc) for assessment 1
   • If heart rate is <50 bpm: Hold Tikosyn as there are no safety data for use at this heart rate 1

2. Monitor for complications:

   • Bradycardia with dofetilide can increase risk of QT prolongation 2
   • Risk of torsades de pointes increases with bradycardia and dofetilide use 4

3. Resume medication when appropriate:

   • Only restart when heart rate returns to >60 bpm 1
   • Re-evaluate QTc before restarting therapy 1

Important Safety Considerations

• Dofetilide requires careful monitoring due to its narrow therapeutic window 5

• The risk of torsades de pointes is approximately 3-4% with intravenous administration and 0.8-1.5% with oral administration 3

• Patients with bradycardia are already at higher risk for QT prolongation and torsades de pointes, making the addition of dofetilide particularly concerning 6

• Tikosyn therapy must be initiated (and re-initiated) in a setting with continuous ECG monitoring with trained personnel present 1

Common Pitfalls to Avoid

• Do not use corrected QT (QTc) formulas when heart rate is <60 bpm; instead use the uncorrected QT interval 1

• Do not restart Tikosyn without hospital monitoring if it has been held for bradycardia, as it requires the same initiation protocol as new starts 1

• Do not overlook other medications that might be contributing to bradycardia (beta-blockers, calcium channel blockers, digoxin) 2

• Avoid concomitant use of other QT-prolonging medications when restarting Tikosyn after a bradycardic episode 2

By following these guidelines, you can safely manage patients on Tikosyn therapy while minimizing the risks associated with bradycardia.