Low levels of cellular omega-3 increase the risk of ventricular fibrillation during the acute ischaemic phase of a myocardial infarction

Aim of the study: Animal studies have demonstrated evidence of an anti-arrhythmic effect of marine n-3 fatty acids (FAs). In humans the same mechanism may explain the observed reduction in sudden cardiac death (SCD) associated with intake of fish. Whether high levels of n-3 FAs could protect against ventricular fibrillation (VF) during the acute ischaemic phase of a myocardial infarction (MI) is, however, not known. Materials and methods: We measured red blood cell content of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) expressed as a percentage of total FAs (the omega-3 index) at admission in 460 patients hospitalised with an acute coronary syndrome. Out of 265 patients suffering their first MI, 10 (cases) experienced an episode of VF during the initial 6 h of symptom onset. The omega-3 index of these patients was compared to that of 185 first-MI patients (controls) free of VF for at least 30 days post-admission. Results: The median value of the omega-3 index in the VF cases was 4.88% as compared to 6.08% in the controls (p = 0.013). After adjustment for age, sex, ejection fraction, high-sensitivity C-reactive protein, use of beta-blocker, differences of infarct characteristics and previous angina pectoris, a 1% increase of the omega-3 index was associated with a 48% reduction in risk of VF (odds ratio (OR) 0.52, 95% confidence interval (CI) 0.28-0.96; p = 0.037). Conclusion: Our study supports an anti-arrhythmic effect of n-3 FAs through their incorporation into myocardial cell membranes, reducing the risk of VF during ischaemia.