The investigators hypothesize that preventive VT substrate ablation in patients with chronic ICM, previously selected based on imaging criteria (BZC mass) for their likely high arrhythmic risk, is safe and effective in preventing clinical VT events.

Fibrotic tissue is known to be the substrate for the appearance of scar-related reentrant ventricular arrhythmias (VA) in chronic ischemic cardiomyopathy (ICM). Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) has proven to be a useful technique in the non-invasive characterization of the scarred tissue and the underlying arrhythmogenic substrate. Previous studies identified the presence of significant scarring (>5% of the LV mass) is an independent predictor of adverse outcome (all-cause mortality or appropriate ICD discharge for ventricular tachycardia or fibrillation) in patients being considered for implantable cardioverter-defibrillator (ICD) placement. Parallelly, the presence of heterogeneous tissue channels, which correlate with voltage channels after endocardial voltage mapping of the scar, can be more frequently observed in patients suffering from SMVT than in matched controls for age, sex, infarct location, and LVEF. However, the lack of solid evidence and randomized trials make LVEF still the main decision parameter when assessing suitability for ICD implantation in primary prevention of SCD. (7,8) In a recent, case-control study, the investigators identified the BZC mass as the only independent predictor for VT occurrence, after matching for age, sex, LVEF and total scar mass. This BZC mass can be automatically calculated using a commercially available, post-processing imaging platform named ADAS 3D LV (ADAS3D Medical SL, Barcelona, Spain), with FDA 510(k) Clearance and CE Mark approval. Thus, CMR-derived BZC mass might be used as an automatically reproducible criterium to reclassify those patients with chronic ICM at highest risk for developing VA/SCD in a relatively short period of time (approx. 2 years).

On the other hand, catheter ablation has become an essential tool in the treatment of ventricular arrhythmias in patients with structural heart disease (SHD). VT ablation techniques have evolved towards substrate-based approaches that permit to abolish multiple VT circuits irrespective of their inducibility or hemodynamic tolerability, improving outcomes with respect to clinical VT ablation. Moreover, VT substrate ablation procedures performed during sinus rhythm and CMR-guided have proven to be safe, with very low procedure related complications.

The investigators hypothesize that preventive VT substrate ablation in patients with chronic ICM, previously selected based on imaging criteria (BZC mass) for their likely high arrhythmic risk, is safe and effective in preventing clinical VT events.

Inclusion Criteria:

• Age > 18 years.
• Chronic, stable ischemic heart disease, irrespectively of the LVEF.
• Life expectancy of > 1 year with a good functional status.
• Documented scar AND a BZC mass > 5.15 g as measured per LGE-CMR and automatic post-processing using the ADAS-3D LV (ADAS 3D Medical SL, Barcelona, Spain).
• Signed informed consent.

Exclusion Criteria:

• Age < 18 years.
• Pregnancy.
• Life expectancy of < 1 year, or bad functional status (NYHA IV functional class).
• Other concomitant structural heart diseases (e.g. congenital, non-ischemic, etc.)
• Previously documented sustained ventricular arrhythmias.
• Impossibility to perform a contrast-enhanced CMR study.
• Calculated BZC mass in the scarred tissue < 5.15 g using the ADAS-3D LV software.
• Concomitant investigation treatments.
• Medical, geographical and social factors that make study participation impractical, and inability to give written informed consent. Patient's refusal to participate in the study.