Red blood cell omega-3 fatty acids and the risk of ventricular arrhythmias in patients with heart failure

Background Epidemiological studies support the protective effect of omega-3 fatty acids on sudden cardiac death. However, patients with structural heart disease and an implantable cardioverter defibrillator (ICD) showed no effect or even a proarrhythmic response to fish oil supplementation. Animal studies suggest different electrophysiologic effects of circulating and incorporated omega-3 fatty acids. Methods In 102 ICD patients in New York Health Association functional class II or III, the fatty acid composition of red blood cells was analyzed by gas chromatography. The omega-3 index was calculated from eicosapentaenoic acid and docosahexaenoic acid. Patients were followed for 1 year, and ventricular arrhythmias requiring antitachycardic therapy were analyzed. Twenty-five healthy subjects served as control. Results In ICD patients, the fatty acid profile was significantly altered and the baseline omega-3 index was significantly elevated, as compared to control subjects (5.12% ± 0.87% vs 4.24% ± 0.96%, P < .001). Kaplan-Meier estimates of probability of ventricular arrhythmias showed significant differences among quartiles of the omega-3 index. Twelve percent of patients in the lowest quartile had ventricular arrhythmias, as compared to 54% of patients in the highest quartile ( P = .022). In a multivariate analysis, the omega-3 index was the only independent predictor for ventricular arrhythmias up to 9 months. At 12 months, a reduced ejection fraction was an additional risk predictor. Conclusions In heart failure patients, the red blood cell fatty acid profile is altered. Omega-3 fatty acids are elevated and predict the risk of ventricular arrhythmias.