Dofetilide (Tikosyn) in Atrial Fibrillation
Dofetilide is a class III antiarrhythmic indicated for conversion of atrial fibrillation/flutter to normal sinus rhythm and maintenance of sinus rhythm in highly symptomatic patients, but requires mandatory in-hospital initiation with continuous ECG monitoring for at least 3 days due to risk of torsades de pointes. 1
Indications
Dofetilide is FDA-approved for two specific uses 1:
- Conversion of atrial fibrillation and atrial flutter to normal sinus rhythm
- Maintenance of normal sinus rhythm (delaying recurrence) in patients with AF/AFl of >1 week duration who have been converted to sinus rhythm
Critical caveat: Because dofetilide can cause life-threatening ventricular arrhythmias, it should be reserved for highly symptomatic patients where AF/AFl significantly impacts quality of life 1. It has NOT been shown effective in paroxysmal atrial fibrillation 1.
Absolute Contraindications
Dofetilide is contraindicated in 1:
- Baseline QTc >440 msec (>500 msec with ventricular conduction abnormalities)
- Congenital or acquired long QT syndromes
- Severe renal impairment (CrCl <20 mL/min)
- Concomitant use of specific drugs:
- Verapamil
- Cimetidine
- Trimethoprim (alone or with sulfamethoxazole)
- Ketoconazole
- Hydrochlorothiazide (alone or in combinations)
- Prochlorperazine, dolutegravir, megestrol
- Known hypersensitivity to dofetilide
Dosing Algorithm
Step 1: Pre-Initiation Assessment 1
Baseline QTc measurement:
- Obtain 12-lead ECG and calculate QTc using average of 5-10 beats
- If QTc >440 msec (>500 msec with ventricular conduction abnormalities): STOP - contraindicated
- If heart rate <60 bpm, use QT interval instead of QTc
- Patients with heart rate <50 bpm have not been studied
Correct electrolytes BEFORE starting:
- Maintain serum potassium in normal range (clinical trials maintained >3.6-4.0 mEq/L)
- Correct hypokalemia and hypomagnesemia
Step 2: Calculate Creatinine Clearance 1
Male: CrCl = (140 - age) × actual body weight (kg) / [72 × serum creatinine (mg/dL)]
Female: CrCl = (140 - age) × actual body weight (kg) × 0.85 / [72 × serum creatinine (mg/dL)]
Step 3: Determine Starting Dose 1
| Creatinine Clearance | Starting Dose |
|---|---|
| >60 mL/min | 500 mcg twice daily |
| 40-60 mL/min | 250 mcg twice daily |
| 20-<40 mL/min | 125 mcg twice daily |
| <20 mL/min | CONTRAINDICATED |
Step 4: Initiation Monitoring 1
At 2-3 hours after FIRST dose:
- Measure QTc
- If QTc increased >15% from baseline OR QTc >500 msec (>550 msec with ventricular conduction abnormalities):
| Original Dose | Adjusted Dose |
|---|---|
| 500 mcg BID | 250 mcg BID |
| 250 mcg BID | 125 mcg BID |
| 125 mcg BID | 125 mcg once daily |
At 2-3 hours after doses 2-5:
- Repeat QTc measurement
- If QTc ever exceeds 500 msec (550 msec with ventricular conduction abnormalities): DISCONTINUE dofetilide immediately 1
Mandatory Monitoring Requirements
During Initiation 2, 3, 1
Hospital admission is mandatory with:
- Continuous ECG monitoring for minimum 3 days
- Personnel trained in managing serious ventricular arrhythmias present
- If electrical or pharmacological cardioversion occurs: monitor for minimum 12 hours post-conversion OR 3 days from initiation, whichever is greater
- Cardiac resuscitation capabilities immediately available
Maintenance Monitoring 2, 3
Every 3-6 months (more frequently if taking other QT-prolonging drugs or changing renal function):
- 12-lead ECG with QTc calculation
- Serum potassium and magnesium
- Serum creatinine for CrCl estimation
If QTc exceeds 500 msec during maintenance: Discontinue dofetilide and monitor until QTc returns to baseline 1
If renal function deteriorates: Adjust dose per Step 3 algorithm above 1
Critical Safety Considerations
Torsades de Pointes Risk 4, 5, 6
The incidence ranges from 0.3-10.5% and is dose-related 5. Risk factors include:
- Heart failure
- Left ventricular hypertrophy
- Bradycardia
- Female gender
- Hypokalemia/hypomagnesemia
- Renal dysfunction
Important note: Recent data suggests dofetilide may be safer in LVH patients than previously thought 7, though guidelines still recommend caution.
Anticoagulation 1
Patients with atrial fibrillation should be anticoagulated according to usual practice prior to electrical or pharmacological cardioversion. Continue anticoagulation post-cardioversion per standard AF management.
Discharge Requirements 1
Patients must have an adequate supply of dofetilide at their individualized dose to allow uninterrupted therapy until they can fill a prescription. This prevents gaps that would require rehospitalization for reinitiation.
Missed Doses 1
If a patient misses a dose, they should NOT double the next dose. Take the next dose at the usual scheduled time.
Cardioversion Timing 1
If patients do not convert to normal sinus rhythm within 24 hours of dofetilide initiation, consider electrical cardioversion. Continue ECG monitoring for 12 hours post-cardioversion or minimum 3 days from drug initiation, whichever is greater.
Clinical Efficacy
Real-world data shows dofetilide achieves acute conversion rates of 66-70% for atrial flutter and approximately 29% for atrial fibrillation within 24-36 hours 4, 5, 8. The 500 mcg BID dose (as modified by the algorithm) demonstrates superior efficacy compared to lower doses for maintaining sinus rhythm 2, 4.
Key advantage: Dofetilide showed neutral mortality in post-MI and heart failure patients, making it one of the few antiarrhythmics safe in structural heart disease 9, 8.