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.