Plain English Summary
Background and study aims
Atrial fibrillation (AF) is a heart condition that can result in an irregular and abnormally heart rate. Many people do not have any symptoms and are not aware they have the conditions. Others may sometimes feel dizzy, become short of breath, feel very tired and become aware of a fast and irregular heart beat (palpitations). The main complication of AF is an increased risk of stroke. Patients are often treated with anticoagulants to help prevent stroke and treatments to help restore a normal heart rhythm and heart rate. There are two key aspects of treatment for AF. The first is protection from stroke, which is done with blood thinning medications. Treatment of the heart rhythm can focus on controlling the rate (frequency of contraction) or controlling the rhythm (managing the regularity of contraction). Rate-control is generally employed first with an intent to reduce the rate at which the lower pumping chambers contract and improve their efficiency. Appropriate medication is used and with this treatment strategy it is accepted that AF will be present as the long term heart rhythm. If symptoms persist despite medication the preferred strategy is to restore sinus rhythm (SR) and regular contraction in all pumping chambers of the heart. This can be done with electric shock treatment (DC cardioversion) together with long-term tablet medication (this is usually a temporary measure), or by a more definitive ‘cauterisation’ therapy (catheter or thoracoscopic surgical ablation). In this study we will be looking at patients with symptomatic long standing persistent AF (i.e. those who have had continuous AF for more than 1 year) who have tried and failed tablet and/or electrical therapy, and thus require rhythm control with a more definitive ablation procedure. At present we do not know what the best ablation technique is for treating symptomatic, long-standing persistent AF (LSPAF). Catheter ablation (CA) is the current invasive treatment available for AF. Thorocoscopic surgical ablation (SA) is not widely available but our hospitals have the expertise to conduct this procedure. CA has been shown to achieve modest degrees of success in restoring normal SR with the caveat that most patients do require ‘multiple’ treatments (usually two or three). SA offers patients an alternative choice of therapy with a keyhole surgical approach. It may have a higher single procedure success rate although there is the potential for greater complication rates. We aim to examine this in detail to help us understand which approach might be better.
Who can participate?
Adults (aged at least 18) with LSPAF.
What does the study involve?
Participants are randomly allocated to one of two groups. Those in group 1 (surgical group) are given minimally invasive thoracoscopic surgical AF ablation under general anaesthesia. Those in group 2 (control group) are given the standard catheter ablation treatment. After surgery, all participants receive the usual care according to standardised hospital protocol. Each participant is also given a implantable loop recorder (ILR) during surgery which then allows heart rhythm monitoring for 12 months. All participants are followed up every 3 months until 12 months after surgery.
What are the possible benefits and risks of participating?
Not provided at time of registration
Where is the study run from?
Royal Brompton and Harefield NHS Foundation Trust (UK) and Liverpool Heart and Chest NHS Foundation Trust (UK)
When is the study starting and how long is it expected to run for?
Recruitment will run from August 2015 to June 2018
Who is funding the study?
National Institute for Health Research (UK)
Who is the main contact?
Mr Matthew Gill
Trial website
Additional identifiers
EudraCT number
Nil known
ClinicalTrials.gov number
NCT02755688
Protocol/serial number
18834
Study information
Scientific title
CAtheter versus thoracoscopic Surgical Ablation in long standing persistent atrial fibrillation: a multicentre randomised controlled trial
Acronym
CASA-AF
Study hypothesis
The aim of this trial is to compare the efficacy of thoracoscopic surgical ablation with catheter surgical ablation for the treatment of longstanding persistent atrial fibrillation (AF).
Ethics approval
NRES Committee South Central - Oxford A, 05/03/2015, ref: 15/SC/0023
Study design
Randomised; Interventional; Design type: Treatment
Primary study design
Interventional
Secondary study design
Randomised controlled trial
Trial setting
Other
Trial type
Treatment
Patient information sheet
Not available in web format, please use the contact details to request a participant information sheet
Condition
Arrhythmia
Intervention
The study will compare outcomes in two groups of patients: one group will undergo catheter and the other surgical ablation of areas giving rise to atrial fibrillation.
1. Thoracoscopic Surgical AF Ablation:
Patients randomised to the surgical arm will receive minimally invasive thoracoscopic surgical AF ablation under general anaesthesia. Transesophageal echocardiography will exclude left atrial thrombus in order for the procedure to progress. Three small chest openings on each side of chest will allow insertion of a radiofrequency clamp which will produce a standardized set of heat leasions on the outer surface of the left atrium. Following completion of the procedure the patients will be managed according to standardised hospital protocol.
2. Catheter AF Ablation:
Patients randomised to the control arm will receive catheter AF ablation preceded by transoesophageal echocardiography to exclude left atrial thrombus. This procedure is also carried out under general anaesthetic and involves insertion of a long catheter via peripheral vascular system. A standard set of radiofrequency lesions is applied to the outer surface of the left atrium using the catheter. Following catheter ablation patients will be managed post-operatively according to the usual hospital protocols.
Patients will have an implantable loop recorder (ILR) inserted at the end of both interventions to allow post-procedure heart rhythm monitoring for 12 months. Furthermore, patients will have detailed follow-up at 3 monthly intervals until 12 months post-procedure.
Intervention type
Procedure/Surgery
Phase
Drug names
Primary outcome measure
The primary efficacy end-point is freedom from atrial arrhythmias after a single procedure without AADs at 12 months
Secondary outcome measures
Previous secondary outcome measures:
1. Intervention-related major complication rate defined as permanent injury or death, that requires intervention for treatment, or prolongs or requires hospitalization for more than 48 hours
2. Clinical success, defined as a 75% or greater reduction of AF burden assessed by implantable loop recorder at 12 months with or without AADs.
3. Freedom from atrial arrhythmia, after multiple procedures without AADs at 12 months
4. Atrial anatomy and function following ablation as assessed by echocardiography and CMR
5. Change in AF symptom score (EHRA score) and quality of life assessments (EQ5D, AFEQT)
6. Quality Adjusted Life Years (QALYs) accrued during the 12-month study period
7.Cost-effectiveness (Incremental Cost per QALY gained) for surgical ablation compared with CA estimated over the 12-month study period (‘within trial’ analysis) and over a lifetime horizon (estimated by modeling)
Current secondary outcome measures as of 22/03/2017:
1. Intervention-related major complication rate defined as permanent injury or death, requires unplanned intervention for treatment, or prolongs or requires unplanned hospitalization for more than 48 hours
2. Clinical success, defined as a 75% or greater reduction of AF burden assessed by implantable loop recorder at 12 months with or without AADs.
3. Freedom from atrial arrhythmia, after multiple procedures without AADs at 12 months
4. Atrial anatomy and function following ablation as assessed by echocardiography and CMR
5. Change in AF symptom score (EHRA score) and quality of life assessments (EQ5D, AFEQT)
6. Quality Adjusted Life Years (QALYs) accrued during the 12-month study period
7.Cost-effectiveness (Incremental Cost per QALY gained) for surgical ablation compared with CA estimated over the 12-month study period (‘within trial’ analysis) and over a lifetime horizon (estimated by modeling)
Overall trial start date
01/01/2015
Overall trial end date
31/12/2019
Reason abandoned (if study stopped)
Eligibility
Participant inclusion criteria
1. Age ≥ 18 years
2. LSPAF (> 12 months’ duration)
3. EHRA > 2
4. Left ventricular ejection fraction ≥ 40%
5. Suitable for either ablation procedure (added 05/05/2016)
Participant type
Patient
Age group
Adult
Gender
Both
Target number of participants
Planned Sample Size: 120; UK Sample Size: 120
Total final enrolment
120
Participant exclusion criteria
Exclusion criteria as of 05/05/2016:
1. Valvular heart disease with severity greater than mild
2. Contraindication to anticoagulation
3. Thrombus in the left atrium despite anticoagulation in therapeutic range
4. Cerebrovascular accident within the previous 6 months
5. Previous thoracic or cardiac surgery (including surgical interventions for AF)
6. Prior left atrial catheter ablation for AF
7. Unable to provide informed written consent
8. Active malignancy, another severe concomitant condition or presence of implanted intracardiac devices that would preclude patient undergoing study specific procedures
9. Pregnant or breast-feeding, or women of childbearing age not using a reliable contraceptive method
Previous exclusion criteria:
1. Significant valvular heart disease
2. Contraindication to anticoagulation
3. Thrombus in the left atrium despite anticoagulation
4. Cerebrovascular accident within the previous 6 months
5. Significant previous thoracic or cardiac surgery (including surgical interventions for AF)
6. Prior left atrial catheter ablation for AF
7. Unable to provide informed written consent
8. Active malignancy or another severe concomitant condition that would preclude patient undergoing study specific procedures
9. Pregnant or breastfeeding, or women of childbearing age not using a reliable contraceptive method
Recruitment start date
30/06/2015
Recruitment end date
30/06/2017
Locations
Countries of recruitment
United Kingdom
Trial participating centre
Royal Brompton and Harefield NHS Foundation Trust (lead trust)
London
SW3 6NP
United Kingdom
Trial participating centre
Liverpool Heart and Chest NHS Foundation
L14 3PE
United Kingdom
Funders
Funder type
Government
Funder name
National Institute for Health Research
Alternative name(s)
NIHR
Funding Body Type
government organisation
Funding Body Subtype
National government
Location
United Kingdom
Results and Publications
Publication and dissemination plan
The results of the study will be published in peer reviewed journals and presented at conferences. We will also disseminate the findings to participants at the end of the study.
IPD sharing plan:
The current data sharing plans for the current study are unknown and will be made available at a later date
Intention to publish date
Participant level data
To be made available at a later date
Basic results (scientific)
Publication list
2018 protocol in: https://www.ncbi.nlm.nih.gov/pubmed/29458408
2020 results in https://pubmed.ncbi.nlm.nih.gov/32860414/ (added 02/09/2020)