A number of large randomized studies have demonstrated the importance of left ventricle ejection fraction (LV EF) for ventrucular tachyarhrythmia's (VT) prediction. The use of this indicator as the sole predictor of high arrhythmic risk requiring ICD implantation is enshrined in the current clinical recommendations. At the same time, many experts consider LV EF as too generalized indicator, which can be an integral indicator of total cardiovascular mortality, but lacks specificity in determining the risk of VT. It is known that only about 20% of patients with ICD implanted for primary prevention of sudden cardiac death (SCD) receive appropriate life-saving therapy.

Purpose of the study: to develop additional criteria for selection of patients with heart failure for implantation of cardioverter-defibrillator for the purpose of primary SCD prevention on the basis of stratification of the risk of occurrence of stable ventricular tachyarrhythmias.

Inclusion Criteria:

• LV EF ≤ 35% inspite of optimal drug therapy of heart failure (3 months and longer)
• NYHA II-IV
• favorable prediction of survival for 1 year or more

Exclusion Criteria:

• secondary SCD prevention
• indications for open heart surgery
• hypertrophic cardiomyopathy
• arrhythmogenic right ventricular dysplasia
• genetic channelopathies