EP-SCOPE is a prospective, multicentric, non-randomized pilot study that aims to estimate the risk of life-threatening ventricular arrhythmia through use of advanced electrophysiological studies in patients with ischemic or non-ischemic cardiomyopathy with left ventricular ejection fraction (LVEF) <50% and risk factors of ventricular arrhythmia, otherwise not considered for implantation of an implantable cardioverter defibrillator (ICD).

The objective is to assess the effectiveness of a risk stratification strategy based on detailed electrophysiological exploration of the left ventricle and programmed ventricular stimulation.

Responsible for 10% of deaths in the general population, sudden cardiac death is mostly caused by malignant ventricular arrhythmias (80%). These arrhythmias mainly occur in cardiomyopathies (75-90%). Currently, the prevention of sudden death is based on risk stratification according to the evaluation of myocardial contractility with indications for prophylactic ICD implantation reserved for LVEF ≤ 35%. This predictor is notoriously insufficient for several main reasons: 1) While ICDs are indicated in patients with LVEF ≤35%, only a minority (2 -5% per year) will suffer from arrhythmia and therefore benefits from ICD implantation, while all will be subject to potential complications. 2) The majority of sudden death (70-80%) occur in patients with LVEF >35%; while they have a lower arrhythmia risk (1-2% per year), they constitute a population four times larger, which is not stratified. 3) Finally, the cardiomyopathy population is broad, and include distinct clinical scenarios that are not specifically addressed.

While conventional electrophysiological studies only boast a limited number of measurements, the proposed strategy is a detailed electrophysiological characterization of the altered ventricle. Measurements include a detailed mapping of the left ventricle in the basal state and during extrastimuli, and programmed stimulation of the right and left ventricle including the simultaneous recording of the Purkinje system.

Follow-up will be performed for 3 years, looking for the occurrence of major arrhythmic events such as: 1) Appropriate therapy (for VT/VF) delivered by an ICD or 2) documented ventricular arrhythmia on ECG, implantable loop recorder or pacemaker or 3) Clinical sudden death.

Inclusion Criteria:

• Patient with cardiomyopathy with 35%\