• |
    • Catheter Ablation
    of atrial fibrillation
    from savage to standard
    Before we know how ablation may fix AF,
    we need to learn how AF is initiated and why it keeps on going and going.
    Pulmonary Veins
    serve as the major source of AF initiator.
    Focal ectopic firing(s) from the muscle sleeve(s) trigger(s) AF.

    Nature Reviews Cardiology 2016.
    Some foci come from other parts of atria, but
    MOST FOCI ARE FROM PUMONARY VEINS.

    Haïssaguerre, M. NEJM 1998;339:659-66
    SUBSTRATE
    Arrhythmogenic substrate = area with conduction delays and block.
    Substrate promotes reentry and helps maintain AF.

    Nature Reviews Cardiology 2016.
    SUBSTRATE
    is more involved in persistent than paroxysmal form.

    2020 Canadian Guidelines for AF
    MECHANISMS OF AF ... IN SHORT
    Firing from PVs initiates AF.
    -->
    AF itself remodels the atria; shorten ERP, creates fibrosis.
    -->
    Remodelling creates substrate for reentry.
    -->
    Reentry keeps AF continue
    Age, obesity, and other medical illnesses also create the substrate.
    -->
    Remodelling creates substrate for reentry.
    -->
    Reentry keeps AF continue
    In paroxysmal AF, PV firings is more involved than Substrate.
    In persistent AF, Substrate is more involved than PV firings.
    {ฮาว-ทู-จี้}
    basic Understanding of AF ablation techniques
    PULMONARY VEIN ISOLATION (PVI)
    Complete isolation of pulmonary veins is the cornerstone of AF ablation.
    2020 ESC Guidelines for AF
    PVI could be performed using Point-by-Point.
    or Single-Shot Device.
    FIRE AND ICE. NEJM 2016.
    How good is PVI?
    Efficacy of PVI in maintaining SR and reducing symptoms
    PVI IN PAROXYSMAL AF
    SYMPTOMATIC | AFTER FAILED AAD
    THERMOCOOL-AF. JAMA 2010.
    PVI IN PAROXYSMAL AF
    SYMPTOMATIC | FIRST LINE
    EARLY-AF. NEJM 2021.
    PVI IN PERSISTENT AF
    SYMPTOMATIC | AFTER FAILED AAD
    PVI is less effective in persistent than paroxysmal AF.
    Heart Rhythm 2020
    SUBSTRATE ABLATION
    Ablation strategy for persistent AF
    COMPLEX FRACTIONATED EGM (CFAE)
    CFAEs correlate with areas of slowed conduction and pivot points of reentrant wavelets. Results from the original trial showed that, in paroxysmal AF, 82% free of atrial arrhythmias in 1yr. In persistent AF, 70% free of atrial arrhythmias in 1yr.
    JACC 2004.
    ADDITIONAL LINE(S)
    Linear ablations may be added along the left atrial roof, mitral isthmus, or box lesions connecting PV lesions.
    STAR-AF II. NEJM 2015.
    CAMERA-MRI. JACC 2017.
    IS PVI+ BETTER THAN PVI ALONE?
    NOT REALLY.
    STAR-AF II. NEJM 2015.
    OVERALL, ABLATION IMPROVE SYMPTOMS AND REDUCE AF RECURRENCE
    In CABANA (43% paroxysmal AF), catheter ablation was effective in reducing recurrence of any AF by 48% and symptomatic AF by 51% compared with drug therapy over 5 years of follow-up.
    CABANA Trial. JAMA 2019.
    GUIDELINES RECOMMENDATIONS
    FOR ABLATION TECHNIQUES
    IA complete isolation of PVs is recommended during all AF ablation.
    IIB using additional techniques beyond PVI may be considered but is not well established.
    2020 ESC Guidelines for AF
    ABLATION TO IMPROVE HARD OUTCOMES
    HFrEF
    In CASTLE-AF, catheter ablation reduced death and HF hospitalization in AF with HFrEF.
    CASTLE-AF. NEJM 2018.
    Symptomatic Paroxysmal or Persistent AF
    In CABANA-AF, catheter ablation reduced primary outcomes (death, stroke, cardiac arrest, and serious bleeding) only in per-protocol analysis but not in ITT. Of note, 27.5% crossed-over from drugs to ablation group.
    CABANA Trial. JAMA 2019.
    In a systematic review and meta-analysis, mortality benefit of catheter ablation is mainly driven by AF with HFrEF patients.
    Circulation: Arrhythmia and Electrophysiology. 2019
    GUIDELINES RECOMMENDATIONS
    INDICATIONS FOR CATHETER ABLATION OF AF
    IA
    2nd line (after failed AAD) | symptomatic AF of any types.
    IA
    1st line | HFrEF (when tachycardiomyopathy is highly probable).
    IIA
    2nd line (after failed AAD) | HFrEF; to improve survival.
    IIA
    1st line | symptomatic paroxysmal AF
    IIB
    1st line | symptomatic persistent AF
    2020 ESC Guidelines for AF
    COMPLICATIONS
    • <0.1%: Periprocedural Death
    • 1%: Major Complications (i.e. tamponade, AE fistula, and stroke)
    • 5%: Moderate Complications (i.e. PV stenosis, phrenic nerve injury, and vascular complication)
    2020 ESC Guidelines for AF
    SPECIFIC COMPLICATIONS
    1. Atrio-esophageal fistula
    • Lethal
    • Require prompt confirmation and intervention
    2. Pulmonary Vein Stenosis
    • Severe stenosis (>75%) is uncommon with the current technology (<1%).
    • Symptoms: occur in 3-6mos, including dyspnea & recurrent pneumonia.
    3. Phrenic Nerve Injury
    • More common in cryoballoon than RF.
    • Mostly transient & spontaneous recover in 6-12mos.
    4. Gastroparesis
    • From vagal denervation.
    • Mostly transient & asymptomatic.
    Ref: 2017 HRS Guidelines for AF Ablation , Circulation: Arrhythmia and Electrophysiology. 2018 , Heart Rhythm 2014. , and Circulation: Arrhythmia and Electrophysiology. 2014.
    PERI-PROCEDURAL STROKE RISK MANAGEMENT
    Eur Heart J 2019
    Before Ablation
    OAC at least 3wks or TEE before ablation
    Right Before Ablation
    No OAC Interruption
    After Ablation
    At least 2 months of OAC.
    Long-term OAC: based on stroke risk profile not the result of the ablation.
    2020 ESC Guidelines for AF
    WHY AF RECURS AFTER ABLATION?
    Because of the reconnected PV(s)
    Circulation: Arrhythmia and Electrophysiology. 2019.
    Because of non-PV trigger(s)
    Heart Rhythm 2017.
    And because of the patient's factors.
    2020 ESC Guidelines for AF
    CONCLUSIONS
    • AF Ablation improves symptoms, reduces recurrence atrial arrhythmias, and improve mortality in selected group of patients.
    • AF Ablation is a 'SAVAGE' therapy after failed AAD.
    • AF Ablation is now a 'STANDARD' therapy in AF with HFrEF or symptomatic paroxysmal AF.
    • Though AF Ablation is a relatively safe procedure, complications do occur.
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