Computed Tomography Targets for Efficient Guidance of Catheter Ablation in Ventricular Tachycardia (MAP-IN-HEART)

Background: Although catheter ablation is a recommended therapeutic option in patients with history of myocardial infarction presenting with sustained ventricular tachycardia (VT),1 the current approach relies on lengthy, poorly reproducible and poorly standardized identification of targets derived from invasive catheter measurements. As a consequence, the rate of VT recurrence remains high, leading to repeat interventions.2 Pre-operative CT scan imaging was shown able to identify arrhythmogenic sites within scar through a detailed analysis of left ventricular (LV) wall thickness.3,4 This study aims at demonstrating that using these as primary targets for ablation is a feasible strategy associated with favorable efficacy, efficiency and safety profiles.

Methods: 40 patients with post-infarction VT referred for catheter ablation will be included over 3 European centres. Pre-operative CT scan will be processed to obtain a 3D model of the patient heart comprising detailed anatomy and LV wall thickness maps. Channels of relatively preserved thickness penetrating within severely thinned scar (i.e. CT-channels) will be identified using a proprietary algorithm developed at the IHU LIRYC, University of Bordeaux, and used as primary targets for catheter ablation. During the intervention, the 3D model along with pre-operatively defined targets will be registered in the 3D mapping space, and each CT-channel will be transected by ablation. The inducibility of VT will then be tested and any VT remaining inducible after CT-channels ablation will be targeted using conventional catheter mapping techniques, with a composite procedural endpoint combining the ablation of all CT channels and the non-inducibility of any VT. Procedural and 6-month follow-up data will be analyzed to assess the feasibility of the approach and report its efficiency, efficacy and safety profiles.

Expected results: the CT-guided ablation strategy is expected to be feasible in a vast majority of post-infarction patients referred for VT ablation, and to be extremely time-efficient, the lengthy diagnostic part of the procedure (catheter mapping) being moved pre-operatively (imaging). The short procedure duration should translate into a favorable safety profile. The strategy should also be associated with a high efficacy in eliminating the arrhythmia, thanks to a more comprehensive definition of targets and to the dedication of the procedure time almost entirely to therapy. In conclusion, the present study should provide solid proof of concept on which randomized controlled trials may be built.

Inclusion criteria

• Age ≥ 18 years
• Indication for catheter ablation intervention with planned preoperative cardiac CT scan
• Prior myocardial infarction (using the international definition of MI: Q waves or imaging evidence of regional myocardial akinesis/thinning in the absence of a non- ischemic cause with documentation of prior ischemic injury)

and

• One of the following monomorphic VT events within last 6 months:

• A: ≥3 episodes of symptomatic VT treated with antitachycardia pacing (ATP),
• B: ≥1 appropriate ICD shocks,
• C: ≥3 VT episodes within 24 hr
• D: sustained VT below detection rate of the ICD documented by ECG or any cardiac monitor
• E: Sustained VT recorded on 12 leads ECG in the absence of ICD
• Signed informed consent
• Affiliated or beneficiary of health insurance

Exclusion criteria

• Unable or unwilling to provide written informed consent.
• Active ischemia (acute thrombus diagnosed by coronary angiography, or dynamic ST segment changes demonstrated on ECG) or another reversible cause of VT (e.g. drug-induced arrhythmia), had recent acute coronary syndrome within 30 days thought to be due to acute coronary arterial thrombosis, or have CCS functional class IV angina. Note that biomarker level elevation alone after ventricular arrhythmias does not denote acute coronary syndrome or active ischemia.
• Are known to have protruding left ventricular thrombus or mechanical aortic and mitral valves.
• Have had a prior catheter ablation procedure for VT
• Presenting arrhythmia: polymorphic VT or ventricular fibrillation (VF).
• Are in renal failure (Creatinine clearance <30 mL/min), have NYHA Functional class IV heart failure, or a systemic illness likely to limit survival to <1 year.
• Pregnancy, breast feeding women and women who are of childbearing age and not practicing adequate birth control. (French HAS criteria or following methods are considered adequate):

• Combined hormonal contraception
• Injected hormonal contraception
• Implanted hormonal contraception
• Progesterone-only hormonal contraception associated with inhibition of ovulation
• Placement of an intrauterine device (IUD)
• Placement of intrauterine hormone-realising system (IUS)
• Patient under legal protection.