Treatment of CTI-Dependent Atrial Flutter
Catheter ablation of the cavotricuspid isthmus is the definitive first-line treatment for CTI-dependent atrial flutter, achieving 90-100% success rates and superior outcomes compared to antiarrhythmic drugs in maintaining sinus rhythm, reducing hospitalizations, and improving quality of life. 1
Primary Treatment Approach
Catheter Ablation (Preferred Strategy)
- CTI ablation creates a line of lesions between the tricuspid annulus and inferior vena cava to interrupt the reentrant circuit 1, 2
- Success requires demonstrating bidirectional conduction block across the CTI, not merely terminating the arrhythmia 1
- 80% of ablation patients remain in sinus rhythm at 21 months versus only 36% with drug therapy 1
- Hospitalization rates are dramatically lower: 22% with ablation versus 63% with antiarrhythmic drugs 1
- Ablation reduces cardiovascular mortality, all-cause mortality, stroke risk, and cardiac decompensation compared to medical therapy 3
Technical Considerations
- Externally-irrigated catheters demonstrate the highest efficacy, achieving bidirectional block in 100% of cases in randomized trials 4
- Large-tip (8-mm) catheters are more effective for straight isthmus anatomy, while externally-cooled catheters perform better with complex CTI anatomy 5
- Age alone is not a contraindication to ablation 2
Alternative Medical Management (When Ablation Contraindicated)
Rate Control Strategy
- Beta-blockers, diltiazem, or verapamil for hemodynamically tolerated flutter 2
- Target ventricular rate control, particularly important as typical flutter presents with 2:1 AV conduction (atrial rate ~300 bpm, ventricular response 150 bpm) 1
Rhythm Control Medications (Second-Line)
- Amiodarone: preferred for patients with heart failure or significant structural heart disease 2
- Dofetilide: requires inpatient initiation and renal function monitoring 2
- Sotalol: monitor for QT prolongation 2
Critical caveat: Class Ic agents (propafenone, flecainide) carry a 15-20% risk of inducing atrial flutter and may slow atrial rate sufficiently to cause dangerous 1:1 AV conduction; must be combined with AV nodal blocking agents 1
Anticoagulation Management
- Follow identical anticoagulation guidelines as atrial fibrillation (CHA₂DS₂-VASc scoring) 1, 2
- Atrial flutter carries a 3% annual thromboembolic risk 2
- Before cardioversion (electrical, chemical, or ablation): ensure therapeutic anticoagulation (INR 2-3), arrhythmia duration <48 hours, or negative TEE 1
- Negative TEE alone does not eliminate thromboembolism risk—continue anticoagulation afterward 1
Important Clinical Pitfalls
Coexisting Atrial Fibrillation
- 25-35% of atrial flutter patients also have atrial fibrillation 1
- CTI ablation alone will not prevent AF recurrence 2
- If atrial flutter becomes the dominant rhythm in AF patients on antiarrhythmics, CTI ablation plus continued drug therapy reduces flutter recurrence and facilitates pharmacologic management 1
Hemodynamic Emergencies
- 1:1 AV conduction can occur during exercise or with rapid AV nodal conduction, causing life-threatening ventricular rates 1
- Patients with accessory pathways capable of rapid conduction require urgent intervention 1
- Immediate DC cardioversion for hemodynamically unstable patients 6
Non-CTI-Dependent Flutter
- More complex circuits (post-surgical scars, left atrial flutter) require specialized mapping and have lower success rates (50-88%) 1
- Refer to experienced centers for suspected non-CTI-dependent flutter, particularly in congenital heart disease or prior atrial surgery 1
Procedural Safety
- Complication rates are low (1-2%) at experienced centers 1
- Potential complications include cardiac perforation, phrenic nerve injury, sinus node dysfunction, and AV block (when ablating near septum or Koch's triangle) 1
- Recent pulsed-field ablation techniques show promise but carry risks of coronary spasm and transient AV block despite preventive measures 7