Pulsed field ablation (PFA) has been demonstrated to be safe and effective in achieving pulmonary vein isolation in patients with atrial fibrillation (AF). Coexisting atrial flutter is common in patients with AF. It is therefore appealing to treat the atrial futters with PFA. The use of PFA for extra-pulmonary ablation, such as linear ablation at the mitral or cavo-tricuspid isthmus (CTI) has been investigated. When PFA is applied near a coronary vessel, acute coronary spasm is a common observation, which has been reported to be reversible and largely mitigated by pre-emptive intravenous or intracoronary nitroglycerine (TNG) injection. A recent clinical study based on qualitative coronary angiogram reported no apparent coronary stenosis 6 months after PFA. However, quantitative measurements were not provided. While acute conduction block is easy to create with pulsed field ablation catheters, the long-term lesion durability is unknown. The circular array pulsed field ablation catheter was shown to be safe and effective in achieving pulmonary vein isolation. This study aims to evaluate the safety and efficacy of pulsed-field ablation for CTI flutters.

This study will be a multicenter prospective cohort study involving 30 patients undergoing ablation for atrial fibrillation and CTI flutter. The decision for ablation will be a clinical decision based on existing class I and II guideline recommendations.

The atrial fibrillation ablation procedure will be performed as per routine clinical practice. Procedure will be performed with a 3-D electro-anatomical system guidance. Pulmonary vein isolation (PVI) will be performed with pulsed field ablation with a circular array catheter (Pulse Select system, Medtronic). After confirming PVI, extrapulmonary ablation will be performed per clinically need. CTI ablation will be performed with PFA as planned.

Patient will be managed by usual clinical care after ablation. They will come back for follow up at 3 months for a remapping procedure. During the remapping procedure, a RCA coronary angiogram will be performed to exclude late coronary damage. A multipolar catheter will be inserted via right femoral vein to check for conduction block across CTI. If there is ongoing conduction, a repeat ablation will be performed with radiofrequency ablation.

Inclusion Criteria:

1. Patients with atrial fibrillation who are clinically planned to undergo AF ablation and atrial flutter ablation per guideline recommendations

Exclusion Criteria:

1. >80 years old or <18 years old
2. Known severe coronary artery disease
3. Prior history of atrial flutter or atrial fibrillation ablation
4. Refusal for remapping or coronary angiogram
5. Contraindication for coronary angiogram
6. Pregnancy
7. Expected life expectancy <1 year
8. Inability to provide informed consent