Effect of Structural Remodeling on Scar Formation as Assessed by DE-MRI of the Left Atrium

NCT ID: NCT01187914

Last Updated: 2012-02-13

Basic Information

• Recruitment Status: COMPLETED
• Total Enrollment: 40 participants
• Study Classification: OBSERVATIONAL
• Study Start Date: 2010-08-31
• Study Completion Date: 2011-06-30

Brief Summary

The purpose of this study is to evaluate the impact of pre-ablation fibrosis on scar formation in the left atrium of the heart. This will be assessed by delayed enhancement magnetic resonance imaging and will be looked at in patients who have undergone successful open irrigated cooled-tipped radio-frequency ablation of paroxysmal atrial fibrillation. Follow-up after ablation will be for 12 months.

Detailed Description

Atrial fibrillation (AF) is an electrophysiological condition characterized by disorganized electrical activity that involves the entire atria. AF manifests initially as paroxysms of arrhythmia that later progress into persistent and permanent forms. It is a progressive disease associated with structural, electrical and contractile changes in the left atrium (LA). A major determinant of the progression of AF is structural remodeling or fibrosis that occurs in the left atrium. A more extensively remodeled atrium presents the substrate needed for the arrhythmia to persist. Structural remodeling is also a major determinant for success of rhythm control strategies in AF. While catheter ablation has reproducibly been shown to be superior to anti-arrhythmic drug (AAD) therapy for rhythm control in AF, the success of this procedure is significantly affected by the extent of structural remodeling present at the time of catheter ablation.

Delayed-Enhancement Magnetic Resonance Imaging (DE-MRI) has been demonstrated to be a very effective modality in identifying fibrotic and scarred cardiac tissue with excellent correlation to electro-anatomical mapping. This is related to the characteristics of Gadolinium, an extracellular contrast agent that is very effective in identifying regions of fibrotic non-viable myocardium. DE-MRI technology can be a very powerful, non-invasive method, of identifying the extent and the distribution of structural remodeling or fibrosis associated with AF. Specific image acquisition sequences have allowed for reproducible identification of high pixel intensity regions within the 2-dimensional images of the atrial wall. 3-Dimensional reconstruction of the entire left atrium then provides a quantification of the overall volume occupied by these hyper-enhanced regions relative to the entire left atrial wall volume. Used prior to catheter ablation, DE-MRI can therefore identify regions of significant structural remodeling or fibrosis. The same technology has also been shown to be very useful in examining the amount and distribution of ablation-induced scarring.

Catheter ablation has emerged as an effective interventional therapeutic modality for AF patients. Current ablation techniques, including pulmonary vein antrum isolation (PVAI), use radiofrequency (RF) energy to induce thermal damage to the LA substrate in an attempt to electrically disconnect and isolate arrhythmogenic foci originating from the pulmonary veins (PVs). Multiple catheter technologies for RF have been developed. Catheters may be either cooled or not. Cooling allows for higher and deeper energy delivery with larger lesion formation. Open irrigation cooled-tip RF ablation of AF is associated with less impedance rise, microbubble formation, and esophageal injury when compared with traditional non-cooled ablation catheters. It is also associated with shorter RF delivery time, fluoroscopy, and procedural time.

Understanding the temporal sequence of events of LA structural remodeling (preceding AF ablation) to scar formation (following AF ablation) can prove valuable in determining whether certain patients are more susceptible to recovery of electrical conduction and recurrence of AF. DE-MRI recently has been introduced as a means to visualize this RF-induced scarring post-ablation. These scans can be reconstructed into three-dimensional (3D) recreations of the LA allowing for further analysis and quantification of the LA scar formation following RF ablation.

Objectives:

Primary Objective

• To evaluate the impact of pre-ablation structural remodeling (fibrosis) on scar formation and progression in the LA as assessed by DE-MRI in patients who have undergone successful open irrigated cooled-tipped RF ablation of paroxysmal atrial fibrillation (PAF), using observational, longitudinal data from the University of Utah Comprehensive Arrhythmia Research & Management (CARMA) Center supported AFIB database (approved IRB #20347) over a 12-month follow up period.

Secondary Objectives

• To determine if secondary variables, such as total ablation time, number of lesions, power delivered, and impedance, may play a significant role in catheter induced scar formation.
• To promulgate future research opportunities in the field of AF, particularly with regards to possible early intervention measures that may impact its progression.
• To adapt treatments aimed at patients with AF who are diagnosed at earlier stages.
• To use DE-MRI to further the knowledge and understanding of RF ablation therapy and to better understand the benefits and longitudinal effects of using scar formation to eliminate the fibrotic tissue that conducts the impulses which leads to AF.

Conditions

Atrial Fibrillation

Study Design

• Observational Model Type: COHORT
• Study Time Perspective: RETROSPECTIVE

Study Groups

Open Irrigation

Those individuals who had an ablation using open irrigation cooled-tip RF ablation.

No interventions assigned to this group

Eligibility Criteria

Inclusion Criteria

• > 17 years-old and < 90 years-old
• Long-term care for PAF
• Participated in regular clinical follow-ups

Exclusion Criteria

• Patients who did not receive long-term follow-up care defined as at least 12-months post ablation.
• Women who were pregnant during the time period to be covered by this study.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 89 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Biosense Webster, Inc.

INDUSTRY

Sponsor Role: collaborator

University of Utah

OTHER

Sponsor Role: lead

Responsible Party

Nassir F. Marrouche, MD

Associate Professor of cardiology

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Nassir F Marrouche, MD

Role: PRINCIPAL_INVESTIGATOR

University of Utah

References

Badger TJ, Oakes RS, Daccarett M, Burgon NS, Akoum N, Fish EN, Blauer JJ, Rao SN, Adjei-Poku Y, Kholmovski EG, Vijayakumar S, Di Bella EV, MacLeod RS, Marrouche NF. Temporal left atrial lesion formation after ablation of atrial fibrillation. Heart Rhythm. 2009 Feb;6(2):161-8. doi: 10.1016/j.hrthm.2008.10.042. Epub 2008 Nov 6.

Reference Type: BACKGROUND

PMID: 19187904 (View on PubMed)

McGann CJ, Kholmovski EG, Oakes RS, Blauer JJ, Daccarett M, Segerson N, Airey KJ, Akoum N, Fish E, Badger TJ, DiBella EV, Parker D, MacLeod RS, Marrouche NF. New magnetic resonance imaging-based method for defining the extent of left atrial wall injury after the ablation of atrial fibrillation. J Am Coll Cardiol. 2008 Oct 7;52(15):1263-71. doi: 10.1016/j.jacc.2008.05.062.

Reference Type: BACKGROUND

PMID: 18926331 (View on PubMed)

Marrouche NF, Guenther J, Segerson NM, Daccarett M, Rittger H, Marschang H, Schibgilla V, Schmidt M, Ritscher G, Noelker G, Brachmann J. Randomized comparison between open irrigation technology and intracardiac-echo-guided energy delivery for pulmonary vein antrum isolation: procedural parameters, outcomes, and the effect on esophageal injury. J Cardiovasc Electrophysiol. 2007 Jun;18(6):583-8. doi: 10.1111/j.1540-8167.2007.00879.x. Epub 2007 May 9.

Reference Type: BACKGROUND

PMID: 17490437 (View on PubMed)

Haissaguerre M, Jais P, Shah DC, Takahashi A, Hocini M, Quiniou G, Garrigue S, Le Mouroux A, Le Metayer P, Clementy J. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med. 1998 Sep 3;339(10):659-66. doi: 10.1056/NEJM199809033391003.

Reference Type: BACKGROUND

PMID: 9725923 (View on PubMed)

Marrouche NF, Schweikert R, Saliba W, Pavia SV, Martin DO, Dresing T, Cole C, Balaban K, Saad E, Perez-Lugones A, Bash D, Tchou P, Natale A. Use of different catheter ablation technologies for treatment of typical atrial flutter: acute results and long-term follow-up. Pacing Clin Electrophysiol. 2003 Mar;26(3):743-6. doi: 10.1046/j.1460-9592.2003.00126.x.

Reference Type: BACKGROUND

PMID: 12698676 (View on PubMed)

Oakes RS, Badger TJ, Kholmovski EG, Akoum N, Burgon NS, Fish EN, Blauer JJ, Rao SN, DiBella EV, Segerson NM, Daccarett M, Windfelder J, McGann CJ, Parker D, MacLeod RS, Marrouche NF. Detection and quantification of left atrial structural remodeling with delayed-enhancement magnetic resonance imaging in patients with atrial fibrillation. Circulation. 2009 Apr 7;119(13):1758-67. doi: 10.1161/CIRCULATIONAHA.108.811877. Epub 2009 Mar 23.

Reference Type: RESULT

PMID: 19307477 (View on PubMed)

Other Identifiers

IRB_00042859

Identifier Type: -

Identifier Source: org_study_id