Substrate abLatIon as Concomitant trEatment for Left Atrial Macroreentrant Tachycardia

Study Overview
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Brief Summary
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SLICE-LAMRT is a multicenter, prospective, randomized, double-blind trial that will be carried out in patients older than 18 years with atypical flutter suspected to be of left atrial origin. The aim of this trial is to evaluate the safety and superiority of a substrate-guided ablation procedure vs the conventional strategy guided by electrical activity. The composite primary endpoint is time to first episode of sustained atrial arrhythmia in the absence of pharmacological antiarrhythmic treatment or new ablation.

Detailed Description
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Left atrial macroreentrant tachycardias (LAMRT), also known as left atrial flutter, represent a small percentage of supraventricular arrhythmiass. These tachycardias occur due to reentrant circuits, that is, electrical activation that occurs around natural anatomical obstacles or scar areas. Classically, by analogy with ventricular tachycardias, these tachycardias are approached by delimiting the circuit (locating the anatomical and functional obstacles), searching for critical areas for their maintenance (isthmuses, generally of slow conduction) and creating controlled lesions that interrupt these circuits (catheter ablation). This requires electromagnetic mapping systems and uses programmed stimulation techniques. This approach treats flutter(s) present at the time of ablation to prevent recurrence. However, it is not uncommon for these patients to develop new macroreentrant circuits during the subsequent clinical course, so the recurrence rate of atrial arrhythmias in this population is relatively high. The goal of this trial is to determine whether substrate-guided ablation of atypical atrial flutter is superior to electrical activation-guided ablation in reducing the recurrence of atrial arrhythmias and increasing the time to first recurrence of atrial fibrillation, atrial flutter, or atrial tachycardia. The investigators hypothesize that ablation not only of inducible tachycardias during the ablation procedure, but guided by the substrate that is most often key to the maintenance of these tachycardias, is superior to conventional treatment in reducing associated clinical events.

Official Title
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Substrate abLatIon as Concomitant trEatment for Left Atrial Macroreentrant Tachycardia - SLICE LAMRT

Conditions
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Atrial Fibrillation

Intervention / Treatment
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* Procedure: Line Set Strategy
* Procedure: Conventional strategy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Atypical flutter with positive F wave in V1, suspected left atrial origin. Age ≥ 18 years Capacity to understand the nature of the study, legal ability and willingness to give informed consent. Exclusion Criteria: Simultaneous participation in a different trial. Presence of congenital heart disease. Suspected flutter of right origin or related to atriotomy scar from previous cardiac surgery. NYHA IV functional class at the time of recruitment. Contraindication to chronic anticoagulation or allergy/intolerance to heparin. Uncontrolled hyperthyroidism. Life expectancy less than 18 months. Presence of heart disease that is expected to require surgery or heart transplantation within 18 months. Pregnancy or the prospect of it in the next 18 months. Left atrium without pathological substrate: area ≥ 4 cm2 of low voltages (<0.5 mV) in the left atrium. Severe fragility (Clinical Frailty Score ≥ 7).

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Line set strategy<br>Pulmonary vein isolation, roof line, posterior wall isolation (posterior box), anterior septal line and cavo-tricuspid isthmus. | Procedure: Line Set Strategy<br>* Substrate-guided ablation procedure of atypical atrial flutter<br>|
| Active Comparator: Conventional strategy<br>Mapping and ablation of the present flutter and those that could be induced later until sinus rhythm is obtained. | Procedure: Conventional strategy<br>* Electrical activation-guided ablation<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Composite primary endpoint | Time to first episode of sustained atrial arrhythmia in the absence of pharmacological antiarrhythmic treatment or new ablation | 18 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Major complications | Death, stroke/systemic embolism, tamponade, during the procedure and immediate post-procedure. | First month | 
| Proportion of patients without recurrence of atrial arrhythmia at 18 months | Maintainance of sinus rhythm by ablation, without requiring electrical cardioversion. | 18 months | 
| Procedure duration | Procedure duration, radiofrequency time, left atrial time (from transseptal puncture to left atrial catheter removal), fluoroscopy time. | In the procedure | 
| Unplanned cardiovascular hospitalisation | Unplanned cardiovascular hospitalisation | 18 months | 
| Unplanned hospitalization for any cause. | Unplanned hospitalization for any cause. | 18 months | 
| All-cause mortality | Mortality due to any cause | 18 months | 
| Cardiovascular mortality | Mortality due to cardiovascular causes | 18 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Atypical atrial flutter, Ablation, Pulmonary veins, Macroreentrant Tachycardia, Scar, Atypical flutter