NCT05881733: BETTER-FIT

Effect of a Bigger Cryoballoon on the Total Antral Lesion Size: Evaluation of POLARx FIT

Completed NA Results posted Last updated 4 December 2025

What this trial tests

NA trial testing POLARx FIT cryoballoon in Atrial Fibrillation in 20 participants. Completed in 23 April 2025.

Timeline

2 October 2023

Primary endpoint
29 April 2024

23 April 2025

Quick facts

Lead sponsor	Erasmus Medical Center
Phase	NA
Status	Completed
Study type	INTERVENTIONAL
Allocation	na
Design	single group
Masking	none
Primary purpose	treatment
Enrollment	20
Start date	2 October 2023
Primary completion	29 April 2024
Estimated completion	23 April 2025
Sites	1 location across Netherlands

Drugs / interventions tested

• POLARx FIT cryoballoon

Conditions studied

• Atrial Fibrillation — all drugs for Atrial Fibrillation →

Sponsor

Erasmus Medical Center

Who can join

18 and older, any sex, with Atrial Fibrillation. Patients with the condition only — healthy volunteers not accepted.

Results — posted to ClinicalTrials.gov

Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.

Percentage of Ablated Left Atrial Posterior Wall With a 31 mm Balloon Size POLARx FIT Primary · Interprocedural (directly after cryoablation)

Low-voltage areas will be quantified using a bipolar voltage \<0.3 mV. The sum of the posterior ablated areas of all pulmonary veins is expressed as a percentage of the total left atrial posterior wall.

Group	Value	95% CI
Study population	35.4	± 13.8

Percentage of Pulmonary Veins With Grade 4 Occlusion With a 31 mm Balloon Size POLARx FIT Secondary · Interprocedural (before cryoablation)

A grade 4 occlusion is defined as complete contrast stasis. Cine acquisitions of contrast vein occlusions was analyzed by two experienced observers.

Group	Value	95% CI
Study population	86

Percentage of Pulmonary Veins With a Single Shot Success Rate Using a 31 mm Balloon Size POLARx FIT Cryoablation Catheter Secondary · Interprocedural (directly after cryoablation)

Pulmonary vein isolation will be determined using conventional criteria: entry- and exit-block as assessed with the circular mapping catheter (POLARMAP).

Group	Value	95% CI
Study population	79

Adverse events — posted to ClinicalTrials.gov

Time frame: 3 months. Reporting threshold: 0%. Adverse-event reports describe events observed during the trial — not all are caused by the drug.

Study population

Serious: 1/20 (5%)

Deaths: 0/20

Serious adverse events (1 terms)

Reaction	System	Study population
Esophageal perforation	Gastrointestinal disorders	—

Most-reported serious reactions: Esophageal perforation.

Data from ClinicalTrials.gov NCT05881733 adverse events section.

Sponsor's own description

The investigators will prospectively evaluate the extent of antral lesion created by the 31 mm balloon size of a novel cryoballoon catheter (POLARx FIT). In 20 patients with paroxysmal atrial fibrillation, the investigators will perform pre- and post-ablation high-definition 3D maps to quantify the extent of lesion created by the 31 mm POLARx FIT cryoballoon.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

1. Prospective evaluation of antral lesion size of the 31-mm size of a novel size-adjustable cryoballoon: Results of the BETTER-FIT study
   van Boven N, Bhagwandien R, Wijchers S, Hoogendijk M, et al · · 2025