.. is all of the above.
.. from triggers to reentry, from electrical to structural remodelling.
- Focal source, mostly from pulmonary veins, can initiate AF.
- Mechanisms include trigger and localized reentry.
- This focal source is more involved in driving AF in paroxysmal > persistent types.
AF provokes shortening of ATRIAL REFRACTORY PERIOD largely due to downregulation of the Calcium inward current.
in the atrial wall
External stressors, such as structural heart disease, HTN, or AF itself, induce
Structural remodelling results in
ELECTRICAL DISSOCIATION favoring reentry
and perpetuation of AF.
Autonomic Nervous System
Activation of parasympathetic and/or sympathetic limbs can provokes AF.
Autonomic input arises from both central nervous system and local ganglionated plexi.
|Mechanisms of AF
|Triggers from PVs and/or non-PVs
- Drugs: CCB, BB
- Ablations: Focal ablation, PVs isolation
- Early Termination
- Drugs that Prolong ERP
- Substrate Modifications: Weight control, Exercise, ?Drugs: ACEI/Statin
- Drugs to control AF: Antiarrhythmic agents
- Ablation: Additional Lines, Complex Fractionated EGM
Autonomic Nerveous System
- Drugs: BB, Hyperthyroid Tx
- Ablation: Glangionated Plexi
- Others: OSA Treatment, Reduction of Endurance Exercise
Pulmonary Vein Isolation
Complete pulmonary vein electrical isolation (PVI) on an atrial level is the best documented target for catheter ablation.
such as roof lines or mitral annulus lines; use the same concept as the Cox-Maze procedure.
Complex Fractioned Electrograms (CFAEs)
- CFAEs are EGMs with highly fractionaed potentials or with very short cycle length (<120ms).
- Correlate with areas of slowed conduction and pivot points of reentrant wavelets.
Which Techniques Reign Supreme?
- Pulmonary vein isolation (PVI) is the most studied and recommended by all societies.
- PVI is recommended as the main strategy for both paroxysmal and persistent AF.
- Extensive ablation does not translate into a better outcome.
- Additional lines and/or CFAEs ablation, however, may be considered in a re-do procedure.
Uninterrupted OACs, either VKA or NOACs, is recommended, presumed that the patient has been therapeutically anticoagulated.
- Uninterrupted OACs is recommended.
- TEE before ablation is reasonable.
Heparin prior to or immediately following transeptal puncture for ACT ≥300s is recommended.
- OACs for at least 2 months post ablation is recommended.
- Decisions regarding continuation of systemic anticoagulation >2 months post ablation should be based on the patient's stroke risk profile and not on the perceived success or failure of the ablation procedure.
Procedural Complications (I/II)
Overall procedural related mortality is less than 1% and major complication rate is
Procedural Complications (II/II)
Atrio-esophageal Fistula is among the most serious and most lethal complications of AF ablation.
Data from RCTs supported the role of catheter ablation for symptomatic paroxysmal AF in reducing symptoms and AF burden when compared with AAD.
Catheter ablation in AF with HFrEF
In an RCT, CASTLE-AF,
selected patients with HFrEF with paroxysmal or persistent AF, catheter ablation for AF had significantly reduced
overall mortality rate, reduced rate of hospitalization for worsening HF, and improved LV ejection
fraction as compared with the medical therapy
In this large RCT, CABANA trial, catheter ablation in patients with AF age >65 or age <65 with CV risk
did not significantly reduce the primary composite end point of death, disabling stroke, serious bleeding, or cardiac arrest.
Catheter Ablation, however, significantly improved quality of life compared to medical therapy.
Catheter ablation for AF in Tachy-Brady Syndrome
AF can lead to atrial fibrosis and sinus node dysfunction.
Observational studies have shown the benefits of AF ablation in reverse remodelling
and potentially waive the need for pacemaker.
Catheter ablation for AF is mainly indicated in a patient with
Indications for Catheter Ablation in AF
|Persistent||1st or 2nd-Line||IIa
|Long-standing Persistent||1st or 2nd-Line||IIb
|Symptomatic with HFrEF||First-Line||IIb
(to reduce mortality & HF Hosp.)
|High-level Athlete||First-Line to reduce negative effects of medications
|Tachy-brady Syndrome||as an alternative to pacemaker
|Asymptomatic||after thorough discussion on the uncertain potential benefits of ablation.
NO ABLATION ...
- No ablation in patients who cannot tolerate anticoagulation.
- No ablation if only to avoid anticoagulation.
Atrioventricular Nodal Ablation
- Serves as the last resource for those who were UNREPONSIVE or INTOLERANT to INTENSIVE rate/rhythm control (IIa).
- Remember that the patients will become PACEMAKER-dependent.
- Consider CRT, rather than a simple pacemaker, in those with impaired LVEF.
- To avoid ventricular arrhythmias post AV nodal ablation, the inital pacing rate should be set at 70-90 bpm.
- Multiple arrhythmic mechanisms involve in initiation and perpetuation of AF.
- Catheter ablation is helpful in improvement of symptomts and quality of life when compared to medications.
- In selected populations of AF with HFrEF, catheter ablation may reduce HF hospitalization and overall mortality.
- Major indication for AF ablation is symptomatic paroxysmal AF.