Lesion Characteristics After Pulsed-Field Ablation in Patients With Atrial Fibrillation and a Left Common Ostium

Atrial fibrillation (AF) is the most common arrhythmia affecting millions worldwide with increasing prevalence. Patients with AF tend to have more comorbidity and an increased stroke and mortality risk. Pulmonary vein isolation (PVI) has become the cornerstone in the invasive treatment of atrial fibrillation (AF). It has been shown that PVI is more effective in maintaining sinus rhythm and improving quality of life compared to antiarrhythmic drugs. Although PVI results in a 98% burden reduction, an AF recurrence is observed in about half of the patients. AF type, comorbidity, and anatomical pulmonary vein variants affect arrhythmia-free survival.

Eighteen per cent of the patients undergoing PVI have a left common ostium (LCO) of the pulmonary veins.(16) A large ostium characterises an LCO, and single-shot devices tend to have worse arrhythmia-free survival than conventional radiofrequency (C-RF) ablation. A proper pulmonary vein occlusion is crucial during cryoballoon ablation. A large ostium can form a distal lesion with the possibility of pulmonary vein potentials proximal to the lesion resulting in AF recurrence. Wide antrum isolation has been shown to improve outcomes, and a distally located lesion can explain the higher AF recurrence rate.(18)

Farapulse (Boston Scientific, MA, US) pulsed-field ablation (PFA) was recently introduced. PFA uses short pulses of high voltages to achieve electroporation and irreversible cell membrane damage.(19) This technique is tissue-specific and limits collateral damage. While PV reconnection has been observed in 47% of patients who underwent cryoballoon or radiofrequency ablation, PFA ablation creates durable lesions in 86% of patients.(19, 20)

Tissue contact is less critical during PFA than conventional RF or cryoballoon ablation. Therefore one could hypothesise that, in patients with an LCO, PFA can be performed at the actual pulmonary vein ostium and that the lesion location is comparable to conventional RF ablation. Reddy et al. included patients with an LCO and presented an electro-anatomical map showing antral isolation. However, it is still being determined how many patients with an LCO were included, and a comprehensive description of the lesion still needs to be provided. Because no studies investigated the lesion characteristic in patients with AF and an LCO after PFA ablation, this study is designed to examine the lesion location in detail with an electro-anatomical map.

This single-centre study will be conducted prospectively in OLVG, Amsterdam, the Netherlands. Patients are eligible for this study if they are admitted for AF ablation because of symptomatic and drug-resistant/intolerant AF and have an LCO (identified by computer tomography (CT) or magnetic resonance imaging (MRI)). All inclusion and exclusion criteria are described in the paragraph ELIGIBILITY.

The operator will map the left atrial voltage in nineteen patients using the Ensite Precision (Abbott inc. IL, US) and the Farawave ablation catheter. First, all patients will be treated with pulsed-field ablation (routine care). Then, when all pulmonary veins are considered isolated, an electro-atomical map of the left atrium will be created.

After the procedure, three experienced operators are asked to draw a line in the anatomical map where they would have performed ablation if C-RF had been used - again, blinded for voltage. Next, the investigators will measure the distance between the line the operators drew and the ablation lesion at three points. The lesion is considered within range if the mean difference is ±10mm at all measurement points.

All study outcomes are specified in the paragraph OUTCOME MEASURES.

Inclusion criteria

• Age > 18 years of age on the day of enrolment of either sex
• Willing to the sign informed consent
• Left atrial volume index measured < 60 ml/m2 within last 12 months
• Documented atrial fibrillation
• Admitted and accepted for PVI
• A left common ostium of the pulmonary veins identified by CT or MRI
• Accepted to receive general anaesthesia

Exclusion criteria

• Patients aged < 18
• Body mass index > 35kg/m2
• Left atrial volume index ≥ 60 ml/m2 within 12 months on MRI or cardiac echo
• New York Heart Association heart failure class III or IV
• Myocardial infarction within three months before the procedure
• Unstable angina pectoris
• Percutaneous coronary interventions within three months before the procedure
• Sudden cardiac death event within three months before the procedure
• A life expectancy of less than one year
• Presence of an atrial tachycardia other than cavotricuspid isthmus-dependent atrial flutter
• History of blood clotting or bleeding abnormalities
• History of a thromboembolic event within six months before the procedure
• A contraindication to anticoagulant
• Clinical significant infection
• Unstable clinical significant medical condition
• Previous left atrium ablation, except successful accessory pathway ablation
• Presence of a left appendage closure device
• Presence of an atrial septum occluder
• Presence of a prosthetic heart valve
• Occlusion of the inferior venous tract
• Enrolment in another study that would interfere with this study