OBJECTIVE: To assess the dynamics of non-invasive electrophysiologic (ventricular arrhythmias, HRV, HRT, mTWA) and humoral (red blood cells omega-3 index) SCD predictors at the background of therapy with omega-3 PUFA in patients with iscemic heart disease and ventricular arrhythmias. MATERIALS AND METHODS: The study included 80 patients. Inclusion criteria were: documented IHD (history of myocardial infarction, stable angina, previous surgical intervention on coronary arteries (coronary artery bypass grafting [CABG], percutaneous coronary intervention [PCI]), positive stress tests, signs of IHD in coronary angiography or computer tomography of coronary arteries; ventricular arrhythmias, according to registered Holter monitoring (PVCs in the number of 250 or more per day and /or intermittent ventricular tachycardia paroxysms); continuous antiarrhytmic therapy for at least 1 month before inclusion (omega-blockers and /or amiodarone), 4) informed consent to participate in the study. RESULTS: All criteria for a good anti-arrhythmic effect (reducing the number of PVCs by 75% and more, paired PVCs by 90% or more, the complete elimination of unstable ventricular tachycardia paroxysms) after 3 months of therapy were observed in 16% of patients, and 6 months after - in 46%. A small but significant increase in the number of PVCs, paired PVCs and ventricular tachycardia paroxysms was noted in the control group. As a result, after 6 months of observation the mean SDNN in patients taking omega-3 PUFA, significantly exceeded the value of the one in the control group. Six months after, the mean value of TO was significantly lower and the mean value of TS - higher than in the control group. After 6 months of therapy with omega-3 PUFA it a significant increase of red blood cells omega-3 index was show by increasing the value of both EPA (an average of 78%) and DHA (an average of 42 %). CONCLUSION: 6 months supplementation with 1 g/day omega-3 PUFA for 6 months in patients with IHD improves the effect of standard antiarrhythmic therapy, reducing the number of isolated and paired PVCs, the number of unstable ventricular tachycardia paroxysms, improves HRT, HRV, increases red blood cells omega-3 index. The long-term (more than 3 months) omega-3 PUFA supplementation must consider be taken into in mTWA assessment to avoid false-positive findings in the SCD risk stratification.