Tikosyn (Dofetilide) for Atrial Fibrillation and Atrial Flutter
Dofetilide is an effective oral Class III antiarrhythmic for rhythm control in atrial fibrillation and atrial flutter, but requires mandatory 3-day inpatient initiation with continuous ECG monitoring due to a 0.8-3.3% risk of torsades de pointes, with strict renal-based dosing and QTc monitoring protocols. 1, 2
Indications and Clinical Efficacy
Dofetilide is FDA-approved for conversion and maintenance of sinus rhythm in symptomatic atrial fibrillation and atrial flutter. 2, 3
- Conversion rates: 29-32% achieve sinus rhythm within 24-36 hours (87% of conversions occur within 30 hours), compared to 1-6% with placebo 4, 1, 3, 5
- Maintenance efficacy: 58-79% remain in sinus rhythm at 1 year versus 25-42% with placebo 4, 1
- Superior efficacy in atrial flutter: 70-75% conversion rate in flutter versus 22-29% in fibrillation 3, 5, 6
- Proven safety in heart failure: Dofetilide and amiodarone are the only antiarrhythmics with neutral mortality in patients with ejection fraction ≤35% (DIAMOND trials) 1, 7
Absolute Contraindications
Do not initiate dofetilide if any of the following are present: 2
- Baseline QTc >440 msec (>500 msec with ventricular conduction abnormalities) 2
- Creatinine clearance <20 mL/min 2
- Concomitant use of: cimetidine, verapamil, trimethoprim (alone or with sulfamethoxazole), prochlorperazine, megestrol, ketoconazole, dolutegravir, or hydrochlorothiazide 2
- Severe hypokalemia or hypomagnesemia (must be corrected before initiation) 4
Mandatory Dosing Algorithm
Step 1: Calculate Creatinine Clearance 2
Use Cockcroft-Gault formula with actual body weight:
- Male: CrCl = [(140 - age) × weight in kg] / [72 × serum creatinine mg/dL]
- Female: CrCl = [(140 - age) × weight in kg × 0.85] / [72 × serum creatinine mg/dL]
Step 2: Determine Starting Dose Based on Renal Function 2
| 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 3: Baseline QTc Measurement 2
Measure QTc using average of 5-10 beats before first dose. If QTc >440 msec (>500 msec with bundle branch block), dofetilide is contraindicated. 2
Step 4: Post-Dose QTc Monitoring Protocol 2
At 2-3 hours after EACH of the first 5 doses, measure QTc and adjust as follows:
If QTc increases >15% from baseline OR exceeds 500 msec (550 msec with conduction abnormalities): 2
| Current Dose | Adjusted Dose |
|---|---|
| 500 mcg BID | Reduce to 250 mcg BID |
| 250 mcg BID | Reduce to 125 mcg BID |
| 125 mcg BID | Reduce to 125 mcg once daily |
If QTc ever exceeds 500 msec (550 msec with bundle branch block) after the second dose, discontinue dofetilide permanently. 2
Mandatory Hospitalization Requirements
All patients must be hospitalized for a minimum of 3 days (or 12 hours after cardioversion to sinus rhythm, whichever is longer) with: 1, 2, 3
- Continuous ECG telemetry monitoring 2
- Immediate access to defibrillator and cardiac resuscitation equipment 3
- QTc measurement 2-3 hours after each of the first 5 doses 2
- Electrolyte monitoring and repletion (maintain potassium ≥4.0 mEq/L, replete magnesium) 4
This hospitalization requirement applies to initial loading AND any dose increases, even if the patient previously tolerated higher doses. 2
Critical Drug Interactions
Absolute contraindications (must discontinue before starting dofetilide): 2
- Cimetidine (increases dofetilide levels by 58%) 2
- Verapamil (contraindicated) 2
- Trimethoprim/sulfamethoxazole (increases dofetilide levels) 2
- Hydrochlorothiazide (increases dofetilide levels) 2
- Ketoconazole, prochlorperazine, megestrol, dolutegravir 2
Safe alternatives for acid suppression: omeprazole, ranitidine, or aluminum/magnesium hydroxide antacids (no effect on dofetilide pharmacokinetics) 2
If dofetilide must be stopped to allow other interacting drugs, observe a 2-day washout period before starting the new medication. 2
Ongoing Maintenance Monitoring
Every 3 months (or more frequently if clinically indicated), reassess: 2
- Renal function: Recalculate creatinine clearance and adjust dose per algorithm if renal function deteriorates 2
- QTc interval: If QTc exceeds 500 msec (550 msec with conduction abnormalities), discontinue dofetilide and monitor until QTc returns to baseline 2
- Electrolytes: Maintain potassium ≥4.0 mEq/L and replete magnesium before each dose adjustment 4
Proarrhythmic Risk Profile
Torsades de pointes occurs in 0.8-3.3% of patients, with 76% of episodes occurring in the first 3 days. 1, 5
Risk factors for torsades de pointes include: 4
- Hypokalemia or hypomagnesemia 4
- Bradycardia or sinus pauses (especially during conversion from AF to sinus rhythm) 4
- Baseline QT prolongation 4
- Female sex 5
- Renal impairment 4
The conversion of AF to sinus rhythm is frequently associated with a sinus pause, creating a high-risk period for torsades de pointes—continuous monitoring with immediate defibrillator access is mandatory during this period. 4
Alternative Rhythm-Control Options
When dofetilide is contraindicated or not tolerated, consider: 4
For Patients WITH Structural Heart Disease or Heart Failure:
- Amiodarone (only other antiarrhythmic proven safe in heart failure with EF ≤35%) 1, 4
- Catheter ablation of cavotricuspid isthmus (>90% long-term success for typical atrial flutter) 8, 4
For Patients WITHOUT Structural Heart Disease:
- Flecainide 50-150 mg twice daily (contraindicated in coronary disease, heart failure, or structural heart disease) 4, 9
- Propafenone (similar contraindications to flecainide; must use with AV nodal blocker to prevent 1:1 flutter conduction) 4, 9
- Sotalol (requires QT monitoring; less effective than dofetilide for maintenance) 4
For Atrial Flutter Specifically:
- Catheter ablation is Class I recommendation (preferred over long-term antiarrhythmics for symptomatic or refractory flutter) 4, 8
- Ibutilide IV for acute conversion (more effective in flutter than fibrillation) 4, 8
Special Populations
Post-Cardiac Surgery:
Dofetilide efficacy has not been demonstrated in post-cardiac surgery patients, and some evidence suggests potential toxicity in this population—amiodarone is preferred. 4
Coronary Artery Disease:
Dofetilide has demonstrated efficacy and safety in patients with coronary artery disease (DIAMOND-MI data), but is positioned as second-line after beta-blockers and sotalol. 1, 4
Severe Hepatic Impairment:
Use with particular caution; patients with severe hepatic impairment have not been studied. 2
Dialysis Patients:
Appropriate dosing is unknown; hemodialysis effectiveness in removing dofetilide is uncertain—avoid use. 2
Anticoagulation Requirements
Atrial flutter carries stroke risk comparable to atrial fibrillation—apply identical anticoagulation guidelines. 4, 8
- For episodes ≥48 hours or unknown duration: Anticoagulate for ≥3 weeks before and 4 weeks after cardioversion 8
- Use CHA₂DS₂-VASc score to determine long-term anticoagulation need (same as for AF) 4, 8
Common Pitfalls to Avoid
Never discharge a patient on dofetilide without ensuring they have an adequate supply at their individualized dose to prevent interruption until a prescription can be filled. 2
If a patient misses a dose, do NOT double the next dose—take the next scheduled dose at the usual time. 2
Before initiating dofetilide after amiodarone, ensure amiodarone plasma levels are <0.3 mcg/mL or wait ≥3 months after amiodarone discontinuation. 2
For other Class I or III antiarrhythmics, observe a washout period of ≥3 plasma half-lives before starting dofetilide. 2
Instruct patients to immediately report symptoms of electrolyte imbalance (excessive diarrhea, vomiting, sweating, loss of appetite/thirst) as these increase torsades risk. 2
Patients must notify all healthcare providers of ongoing dofetilide therapy before any new medication is prescribed, including over-the-counter preparations. 2