for people ages 18 years and up (full criteria)
at San Diego, California and other locations
study started
completion around



This clinical investigation is intended to demonstrate the safety and effectiveness of ventricular ablation therapy using the FlexAbility Sensor Enabled Ablation Catheter in patients with drug-refractory monomorphic ventricular tachycardia in whom ventricular tachycardia recurs despite antiarrhythmic drug therapy or when antiarrhythmic drugs are not tolerated or desired.

Official Title

FLExAbility Sensor Enabled Substrate Targeted Ablation for the Reduction of Ventricular Tachycardia (LESS-VT) Study


This is a regulated, prospective, multi-center trial designed to evaluate the safety and effectiveness of the FlexAbility[TM] Ablation Catheter, Sensor Enabled[TM] (FlexAbility SE) catheter to obtain an indication to treat monomorphic ventricular tachycardia (MMVT) in the United States of America (US). The clinical trial has two cohorts: one is a randomized ischemic cardiomyopathy (ICM) cohort and the second is a concurrent single-arm non-ischemic cardiomyopathy (NICM) cohort. Four hundred ten (410) subjects with drug refractory sustained MMVT and ICM and 182 subjects with drug refractory sustained MMVT and NICM will be enrolled at up to 35 centers worldwide. Study subjects who have drug refractory sustained MMVT and ICM will be randomized 1:1 to treatment with the FlexAbility SE catheter ablation system in the Treatment group, or the ThermoCool, ThermoCool NaviStar, or ThermoCool SmartTouch Ablation Catheter from Biosense Webster in the Control group. Since at study start there was no approved device for VT ablation in patients with NICM to use as a comparator, subjects who have drug refractory MMVT and NICM will be treated with the FlexAbility SE catheter ablation system only.


Ventricular Tachycardia, Tachycardia, Market Approved RF Ablation System, FlexAbility SE Ablation Catheter


You can join if…

Open to people ages 18 years and up

  • Structural heart disease (ischemic or non-ischemic) with one of the following:
    • Confirmed diagnosis via echocardiography and/or cardiac CT/MRI [computed tomography/magnetic resonance imaging], or
    • Left ventricular ejection fraction (EF) <40% (documented within the last 6 months via echocardiography, or
    • Arrhythmogenic RV [right ventricular] cardiomyopathy/dysplasia (per 2010 ARVC/D [arrhythmogenic right ventricular cardiomyopathy/dysplasia] Task Force Criteria).27
  • At least one documented episode of sustained MMVT by either EGM [cardiac electrogram] or ECG [electrocardiogram] in the 6 months prior to enrollment
  • Implanted with a market released ICD [implantable cardioverter-defibrillator] or CRT-D [cardiac resynchronization therapy-defibrillator] for at least 30 days prior to index ablation procedure
  • Refractory (i.e. not effective, not tolerated or not desired) to at least one anti-arrhythmic medication (either amiodarone or sotalol) for treatment of MMVT
  • At least 18 years of age
  • Informed of the nature of the study, agreed to its provisions and has provided written informed consent as approved by the Institutional Review Board/Ethics Committee (IRB/EC) of the respective clinical study site.
  • Able and willing to comply with all study requirements

You CAN'T join if...

  • Implanted with a subcutaneous ICD
  • Implanted with a ventricular assist device (VAD) (e.g. TandemHeart)
  • Currently receiving support, or anticipated to receive support prior to the index ablation procedure, via extracorporeal membrane oxygenation (ECMO)
  • Presence of intracardiac thrombus verified via computer tomography (CT), magnetic resonance imaging (MRI), transesophageal echocardiogram (TEE), or transthoracic echocardiogram (TTE) within 48 hours prior to the index ablation procedure or intra-procedure intracardiac echocardiography (ICE)

    o For subjects with a history of AF [atrial fibrillation], this verification must be done via TEE or ICE

  • ST elevation myocardial infarction (MI) within 60 days prior to index ablation procedure
  • Previous cardiac surgery (e.g. ventriculotomy, atriotomy, coronary artery bypass graft), within 60 days prior to index ablation procedure
  • Percutaneous coronary intervention (PCI) within 30 days prior to index ablation procedure
  • Idiopathic VT
  • Incessant VT (continuous sustained VT that promptly recurs despite repeated intervention for termination over ≥3 hours) necessitating immediate treatment or requiring hemodynamic support prior to the ablation procedure
  • VT/VF [ventricular tachycardia/ventricular fibrillation] thought to be from channelopathies
  • Reversible cause of VT
  • Severe aortic stenosis or flail mitral valve
  • Mechanical mitral and aortic valve
  • History of stroke with modified Rankin scale > 3 (See Appendix C)
  • Unstable angina
  • Chronic NYHA [New York Heart Association] Class IV heart failure
  • Ejection fraction < 15%
  • Thrombocytopenia (defined as platelet count <80,000) or coagulopathy
  • Contraindication to systemic anticoagulation (i.e. heparin, warfarin, or a direct thrombin inhibitor)
  • Women who are pregnant or nursing
  • Active uncontrolled infection
  • Other anatomic or co morbid conditions or other medical, social, or psychological conditions that, in the investigator's opinion, could limit the patient's ability to participate in the study or to comply with follow up requirements, or impact the scientific soundness of the study results
  • Enrolled in an investigational study evaluating another device or drug that would confound the results of this study
  • Have a life expectancy of less than 12 months due to any condition.


  • University of California at San Diego (UCSD) Medical Center
    San Diego California 92103 United States
  • Ronald Reagan UCLA Medical Center
    Los Angeles California 90095 United States


in progress, not accepting new patients
Start Date
Completion Date
Abbott Medical Devices
Study Type
About 592 people participating
Last Updated