Red blood cell fatty acid levels improve GRACE score prediction of 2-yr mortality in patients with myocardial infarction

BackgroundBlood omega-3 and omega-6 fatty acid levels have been associated with reduced risk for total mortality in patients with stable coronary heart disease (CHD), but their relationships with mortality in the setting of myocardial infarction (MI) are unknown.ObjectiveTo determine the association between red blood cell (RBC) fatty acid levels measured at admission and 2-year mortality in MI patients, independent of the GRACE risk score, a traditional mode of risk stratification.DesignAdmission RBC fatty acid levels were measured in patients enrolled in a prospective, 24-center MI registry (TRIUMPH). Two-year mortality was modeled with Cox proportional hazards regression to assess the extent to which the inclusion of fatty acid levels would improve, over and above the GRACE score, risk stratification for 2-year mortality.ResultsRBC fatty acid data were available from 1144 patients who did not report taking fish oil supplements after discharge. Two RBC fatty acids [eicosapentaenoic acid (EPA) and docosapentaenoic n − 6 (DPA)] were univariate predictors of total mortality. The combined fatty acid c-statistic (0.60, p < 0.001) improved the c-statistic of the GRACE score alone from 0.747 (p < 0.001) to 0.768 (p < 0.05 vs. GRACE alone). The net reclassification index improved by 31% (95% CI, 15% to 48%) and the relative incremental discrimination index improved by 19.8% (7.5% to 35.7%).ConclusionRBC EPA and DPA n − 6 levels improved the prediction of 2-yr mortality over and above the GRACE score in MI patients.