The trial stopped prematurely because of enrollment challenges.

The electrical isolation of the pulmonary veins (PVI) is the cornerstone of current ablation techniques for the treatment of atrial fibrillation (AF) because the PV is the most common trigger of AF. Wide bi-antral circumferential ablation (WACA) is more effective than segmental PV isolation in achieving freedom from total atrial tachyarrhythmia recurrence at long-term follow-up. Therefore, it is widely accepted as initial ablation strategy. However, the WACA technique requires a much larger number of ablation and higher energy to achieve complete isolation because of thick atrial myocardial sleeves with multiple muscle layers present in most of the PV antrum, which is less likely to achieve homogenous transmural lesions in the entire circumference with the currently available ablation technologies. Meanwhile, muscular discontinuities and abrupt changes of the fiber orientation in human PV-Left atrium (LA) junction are previously reported, and electrical PV isolation can usually be achieved without complete circumferential ablation. However, the current electroanatomical mapping (EAM) system has a limitation to understand the complex relationship of PV-LA junction mainly due to relatively low resolution.

The Rhythmia mapping system (BostonScientific, Inc, Cambridge, MA) is a new system provides ultra-high-resolution EAM using a small basket array of 64 electrodes (IntellaMap Orion, Boston Scientific). Owing to better resolution, this new system capable of rapidly and accurately identify critical isthmuses and low-voltage regions of interest and also allows automatic acquisition and accurate annotation of the electrograms, without the need for manual correction.

In this context, we hypothesized that rapid and precise identification of activation pattern of PV-LA junction by Rhythmia system could allow complete, durable electrical isolation of PVs without circumferential antral ablation.

Inclusion Criteria:

1. Age over 20 years old and under 80 years old
2. Patients with non-valvular paroxysmal atrial fibrillation
3. Patients having atrial fibrillation even after receiving continued treatment with at least 1 antiarrhythmic drug for more than 6 weeks
4. Patients who could have informed consent
5. Patients who are available for a follow-up of more than at least three months after the catheter ablation

Exclusion Criteria:

1. Patients unsuitable for catheter ablation due to a previous history of pulmonary surgery or structural heart disease
2. Patients who cannot receive standard treatments such as anticoagulation therapy needed before the radiofrequency catheter ablation
3. Patients in the subject group vulnerable to a clinical study
4. Patients who had undergone a prior catheter ablation for atrial fibrillation

Paroxysmal atrial fibrillation patients who received pulmonary vein isolation using Rhythmia HDx mapping system in Keimyung University Dongsan Medical Center.