Personalized Atrial Fibrillation Ablation With QDOT

August 29, 2023 updated by: Antonio Berruezo, MD, PhD

Personalized Atrial Fibrillation Ablation With the QDOT Catheter - The QDOT-by-LAW Trial

Circumferential pulmonary vein isolation (PVI) has become a mainstay in the treatment of atrial fibrillation (AF), particularly in symptomatic patients with paroxysmal AF (PAF) intolerant or refractory to medical treatment. The safety and short-term performance of the novel QDOT® catheter (Biosense Webster, Irvine, CA, USA), that allows for a high-power short-duration (HPSD) ablation, has already been evaluated in the QDOT-FAST clinical study, with favorable data on feasibility and safety, and lowered fluoroscopy and procedure times needed to achieve complete PVI. HPSD ablation was based on immediate heat formation during the resistive phase, affecting a small tissue depth at 90 W/4 s (irrigation at 8 ml/min) with a temperature limit of 65ºC.

However, up to date there are no randomized studies evaluating the real usefulness of the QDOT® catheter. Longer-term follow-up is still required to verify the long-term effectiveness and correlations between short-term follow-up and arrhythmia recurrence when using this catheter. The impact of this novel catheter, when used in conjunction with a personalized ablation protocol that uses the information of left atrial wall thickness (LAWT) to modulate the AI target at each ablation point, compared with a standard ablation protocol following the published CLOSE study criteria is already unknown.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Circumferential pulmonary vein isolation (PVI) has become a mainstay in the treatment of atrial fibrillation (AF), particularly in symptomatic patients with paroxysmal AF (PAF) intolerant or refractory to medical treatment. Dormant conduction and pulmonary vein reconnections are responsible for AF/atrial tachycardia (AT) recurrences owing to incomplete non-transmural ablation lesions that generate gaps on ablation lines.

The advent of contact force (CF) catheters has represented a significant milestone when reaching better efficiency in RF delivery, helping to achieve better PVI rates after AF ablation. The benefits of CF sensing have been already demonstrated in both the SMART AF (THERMOCOOL® SMARTTOUCH® Catheter for the Treatment of Symptomatic Paroxysmal Atrial Fibrillation) and the TOCCASTAR (TactiCath® Contact Force Ablation Catheter Study for Atrial Fibrillation) studies. Moreover, CF stability is also an important predictor of reduced arrhythmia recurrence.

Recently, ablation index (AI) (CARTO3® V4; Biosense Webster, Inc, Diamond Bar, CA, USA) was developed as a novel marker of lesion quality that, for the first time, incorporates CF as well as duration, and power delivery. The recent CLOSE clinical study analyzed the utility of ablation index (AI), a novel formula developed to assess real-time effect of RF delivery and improve the rates of permanent PVI, with 91.3% of the patients free from AF/AT/atrial flutter (AFL) at 12 months follow-up. The CLOSE protocol targeted an interlesion distance (ILD) of 6 mm and AI ≥ 400 at the posterior wall and ≥550 at the anterior wall.

However, another recent study revealed that AI, while being very reliable across a range of CF values, may be 'penalized' by small contact angles and high-power RF applications, which could decrease the lesion size at the same AI. The small lesion size at narrow contact angle may be explained by tip temperature drop due to saline flow from irrigation holes located at the side of the catheter tip during RF application. Bourier et al. reported that extremely high-power RF applications (> 50 W) resulted in significantly smaller lesion depth for short-duration applications (n = 120).

In a swine model, high-power short-duration (HPSD) ablation resulted in 100% contiguous lines with all transmural lesions, whereas standard ablation (25 W for 20 s) had linear gaps in 25% and partial thickness lesions in 29%. The authors of this experimental study used a novel ablation catheter that incorporates 6 thermocouples symmetrically embedded in the circumference of the tip electrode, named QDOT® catheter (Biosense Webster, Irvine, CA, USA). This catheter permits to control the confounding effect of the cold irrigation fluid during ablation, while having an improved irrigation system. In the same study, ablation with HPSD produced wider lesions at similar depth, and improved lesion-to-lesion uniformity with comparable safety endpoints. Given the aforesaid, it can be hypothesized that larger diameter of HPSD lesions might contribute to a complete encirclement of PV, by ensuring better contiguity between adjacent lesions, while the reduced lesion depth may still achieve lesion transmurality in atrial tissue, diminishing the risk of collateral tissue damage.

The safety and short-term performance of the QDOT® catheter (Biosense Webster, Irvine, CA, USA) has already been evaluated in the QDOT-FAST clinical study (Clinical Study for Safety and Acute Performance Evaluation of the THERMOCOOL SMARTTOUCH SF-5D System Used With Fast Ablation Mode in Treatment of Patients With Paroxysmal Atrial Fibrillation), with favorable data on feasibility and safety, and lowered fluoroscopy and procedure times needed to achieve complete PVI. HPSD ablation was based on immediate heat formation during the resistive phase, affecting a small tissue depth at 90 W/4 s (irrigation at 8 ml/min) with a temperature limit of 65ºC.

Up to date, there are no randomized studies evaluating the real usefulness of the QDOT® catheter. Moreover, longer-term follow-up is required to verify the long-term effectiveness and correlations between short-term follow-up and arrhythmia recurrence when using this catheter. The impact of the QDOT® catheter, when used in conjunction with a personalized ablation protocol that uses the information of left atrial wall thickness (LAWT) to modulate the AI target at each ablation point, compared with a standard ablation protocol (CLOSE study criteria) is already unknown.

Our research hypothesis is that QDOT-by-LAW, a personalized protocol that uses a dedicated vHPSD catheter, a multichannel radiofrequency (RF) generator with a vHPSD ablation mode, and integrated LAWT information to adapt the ablation index (AI) target to the subjacent LAWT, is safe, while showing at least the same efficacy and better efficiency than the CLOSE protocol.

Study Type

Interventional

Enrollment (Estimated)

77

Phase

  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Spain
      • Barcelona, Spain, 08004
        • Recruiting
        • Teknon Medical Center
        • Contact:
        • Contact:
        • Sub-Investigator:
          • Giulio Falasconi, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

14 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age > 18 years.
  • Indication for paroxysmal atrial fibrillation ablation.
  • Signed informed consent

Exclusion Criteria:

  • Age < 18 years.
  • Pregnancy.
  • Previous AF redo procedure.
  • Impossibility to perform a pre-procedural CT scan.
  • Concomitant investigation treatments.
  • Medical, geographical and social factors that make study participation impractical, and inability to give written informed consent. Patient's refusal to participate in the study.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: QDOT-LAWT

A QDOT® 3.5-mm open-irrigated contact force-sensing RF ablation catheter (Biosense Webster, Inc., Irvine, CA, USA) will be used.

The primary ablation mode for PVI will depend on the calculated LAWT at each atrial point, as follows:

**< 3.5-mm LAWT (red, and yellow colors): vHPSD ablation will be performed. If <1-mm LAWT (red color): Power 90 W; the duration of RF applications will be reduced to 2 seconds. If 1-3.5 mm LAWT (yellow color): Power 90 W; the duration of RF applications will be 4 seconds, according to the QDOT-FAST protocol.

**> 3.5-mm LAWT (green color): QMODE ablation will be performed. 50 W with AI target = 500
Device: Atrial fibrillation ablation using the QDOT® catheter
Atrial fibrillation ablation will be performed using the QDOT® catheter. The ablation mode will be selected according to the MDCT-derived LAWT information.
Other Names:
  • Pulmonary vein isolation
Active Comparator: CLOSE

In the CLOSE arm, the use of MDCT-derived LAWT information will not be available for the operator. A ThermoCool® SmartTouch® 3.5-mm open-irrigated contact force-sensing RF ablation catheter (Biosense Webster, Inc., Diamond Bar, CA, USA) will be used. The ablation will be performed using a proprietary RF generator (SMARTABLATE®; Biosense Webster, Diamond Bar, CA, USA).

Ablation will be performed according to the CLOSE study settings: Power-controlled mode (without ramping) with 25 to 35 W (irrigation flow 30 ml/min). RF will be delivered until an AI of ≥ 400 at the posterior wall/roof and ≥ 550 at the anterior wall are reached.
Procedure: Standard atrial fibrillation ablation
Atrial fibrillation ablation will be performed using the SmartTouch® catheter. The ablation parameters will be adjusted according to the settings previously described in the CLOSE study.
Other Names:
  • Pulmonary vein isolation

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Clinical efficacy
Time Frame: 1 year
Survival free of any atrial arrhythmia at the 3-month, 6-month, and 12-month follow-up.
1 year

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Procedure time
Time Frame: 1 month
Procedure time (skin to skin)
1 month
Radiofrequency time
Time Frame: 1 month
Radiofrequency time
1 month
Number of radiofrequency applications
Time Frame: 1 month
Number of applications (total/per PVI RF line/per segment)
1 month
Fluoroscopy time
Time Frame: 1 month
Fluoroscopy time
1 month
First pass isolation rate
Time Frame: 1 month
First pass isolation rate
1 month
Early PV reconnection rate
Time Frame: 1 month
Early PV reconnection rate
1 month
Incidence of peri-procedural complications
Time Frame: 1 month
Incidence of peri-procedural complications
1 month

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Antonio Berruezo, MD, PhD

Investigators

  • Principal Investigator: Antonio Berruezo, MD, PhD, Centro Medico Teknon

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 1, 2022

Primary Completion (Actual)

December 1, 2022

Study Completion (Estimated)

December 30, 2023

Study Registration Dates

First Submitted

February 29, 2020

First Submitted That Met QC Criteria

March 4, 2020

First Posted (Actual)

March 6, 2020

Study Record Updates

Last Update Posted (Actual)

August 30, 2023

Last Update Submitted That Met QC Criteria

August 29, 2023

Last Verified

August 1, 2023

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • QDOT-by-LAW

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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