Background: Polyunsaturated fatty acids (PUFAs) have important roles in the pathogenesis of cardiovascular diseases. However, the clinical significance of omega-6 PUFAs in acute cardiovascular disease remains unknown.
Methods: We enrolled 417 consecutive patients with acute cardiovascular disease admitted to the cardiac intensive care unit at Juntendo University Hospital between April 2012 and October 2013. We investigated the association between serum PUFA levels and long-term mortality. Blood samples were collected after an overnight fast, within 24 h of admission. We excluded patients who received eicosapentaenoic acid therapy and those with malignancy, end-stage kidney disease, chronic hepatic disease, and connective tissue disease.
Results: Overall, 306 patients (mean age: 66.4 ± 15.0 years) were analysed. During the follow-up period of 2.4 ± 1.2 years, 50 patients (16.3%) died. The dihomo-gamma-linolenic acid (DGLA) levels, arachidonic acid (AA) levels, and DGLA/AA ratio were significantly lower in the nonsurvivor group than in the survivor group (DGLA: 23.2 ± 9.8 vs. 31.5 ± 12.0 μg/ml, AA: 151.1 ± 41.6 vs. 173.3 ± 51.6 μg/ml, and DGLA/AA: 0.16 ± 0.05 vs. 0.19 ± 0.06, all p < 0.01). Kaplan-Meier curves showed that survival rates were significantly higher in the higher DGLA, AA, and DGLA/AA groups than in their lower counterparts (DGLA and AA; p < 0.01, DGLA/AA; p = 0.01), although omega-3 PUFAs were not associated with prognosis. Furthermore, in patients with acute decompensated heart failure (ADHF), survival rates were significantly higher in the higher DGLA, AA, and DGLA/AA groups than in their lower counterparts (DGLA and AA; p < 0.01, DGLA/AA; p = 0.04). However, among patients with acute coronary syndrome, none of the PUFA levels were associated with prognosis. Among patients with ADHF, after controlling for confounding variables, DGLA and DGLA/AA were associated with long-term mortality [DGLA: hazard ratio (HR), 0.94; 95% confidence interval (CI), 0.88-0.99; p = 0.01 and DGLA/AA: HR, 0.87; 95% CI, 0.77-0.97; p < 0.01], whereas AA was not associated with prognosis.
Conclusion: Low omega-6 PUFA levels, particularly DGLA, and a low DGLA/AA ratio predict long-term mortality in patients with acute cardiovascular disease and ADHF.
Trial registration: UMIN-CTR; UMIN000007555 .
Keywords: Arachidonic acid; Dihomo-gamma-linolenic acid; Inflammation; Nutrition; Omega-6; Polyunsaturated fatty acids.