# Shortest pulmonary vein atrial fibrillation cycle length identifies pulmonary vein isolation responders beyond clinical atrial fibrillation pattern: the FARS-AF II study

## TL;DR

A new method to measure heart rhythm in the pulmonary veins can predict which patients will benefit from a specific treatment for atrial fibrillation.

## Contribution

A novel method (PV-FARS10) identifies PVI responders in atrial fibrillation patients with a 155 ms cut-off for recurrence prediction.

## Key findings

- Patients with PV-FARS10 ≤ 155 ms had significantly lower AF recurrence rates after PVI.
- The 155 ms cut-off was effective in both paroxysmal and persistent AF patients.
- Paroxysmal AF patients were more likely to have PV-FARS10 ≤ 155 ms than persistent AF patients.

## Abstract

Atrial fibrillation cycle length (AF-CL) measured in the pulmonary veins (PVs) with a novel simple method [the average of the 10 consecutive Fastest Atrial Repetitive Similar signal interval (FARS10)] accurately identified pulmonary vein isolation (PVI) responders in a preliminary study. This study aims to evaluate differences in PV-FARS10 between paroxysmal and persistent AF and to define the optimal cut-off to predict PVI-only approach success in a large population.

We prospectively enrolled consecutive patients with persistent or paroxysmal AF undergoing first PVI in a single-centre study. The primary endpoint was atrial arrhythmia recurrence. A total of 219 patients (61.8 ± 11.2 years, 25.1% female) were included, with 70 patients (32%) having paroxysmal AF and 149 patients (68%) persistent AF. After a median follow-up of 18.0 [interquartile range (IQR) 10.2–42.3] months, 72 (32.9%) patients experienced AF/atrial flutter (AFL)/atrial tachycardia (AT) recurrence. Patients with shortest PV-FARS10 ≤ 155 ms had a lower rate of AF/AFL/AT recurrence compared to those with shortest PV-FARS10 > 155 ms in the overall population (HR 0.34, P < 0.001), in persistent AF (HR 0.40, P = 0.002), and in paroxysmal AF (HR 0.18, P = 0.01). In multivariable analysis—which included age, sex, body mass index, CHA2DS2-VA score, obstructive sleep apnoea syndrome, duration of AF, AF type (paroxysmal vs. persistent), left ventricular ejection fraction, left atrial volume index, shortest PV-FARS10/left atrial appendage-FARS10, and AF termination during ablation—only the shortest PV-FARS10 ≤ 155 ms was the significant predictor of AF/AFL/AT recurrence-free survival in the overall population (HR 0.45, CI: 0.26–0.78, P = 0.005). Paroxysmal AF patients more frequently had shortest PV-FARS10 ≤ 155 ms than persistent AF patients (61.4% vs. 42.3%, P = 0.009).

PV-FARS10 can accurately identify PVI responders among patients with persistent and paroxysmal AF. Patients with slow PV (shortest PV-FARS10 > 155 ms) experience a higher rate of AF/AFL/AT recurrence after PVI-only approach. The shortest PV-FARS10 ≤ 155 ms occurs more frequently in paroxysmal AF patients than in persistent AF patients.

Graphical AbstractLeft: Calculation of the pulmonary vein (PV) FARS10 PV activity is recorded for 1 min and the 10 fastest consecutive atrial repetitive similar signals are averaged. Center: A cut-off of 155 ms stratifies patients with ‘fast PV’ (≤155 ms, lower recurrence risk after PVI-only, i.e. PVI-only responders) and ‘slow PV’ (>155 ms, higher recurrence risk, i.e. PVI-only non-responders). Right: The predictive value of the 155 ms cut-off was consistent in both paroxysmal and persistent AF patients.For image description, please refer to the figure legend and surrounding text.

Left: Calculation of the pulmonary vein (PV) FARS10 PV activity is recorded for 1 min and the 10 fastest consecutive atrial repetitive similar signals are averaged. Center: A cut-off of 155 ms stratifies patients with ‘fast PV’ (≤155 ms, lower recurrence risk after PVI-only, i.e. PVI-only responders) and ‘slow PV’ (>155 ms, higher recurrence risk, i.e. PVI-only non-responders). Right: The predictive value of the 155 ms cut-off was consistent in both paroxysmal and persistent AF patients.