Introduction: We previously investigated the prognostic utility of red blood cell (RBC) n-3 fatty acids (FAs) in survivors of an acute myocardial syndrome (ACS) but found no relationship with all-cause mortality and cardiac death or MI after two years. Here we extend our follow-up to 7 years, focusing on the potential predictive power of RBC n-6 FAs.
Hypothesis: We hypothesize that dihomo-gamma-linolenic acid (DGLA) may be a useful predictor of future cardiovascular events following an acute coronary syndrome.
Methods: We included 398 ACS patients presenting with increased troponin-T (TnT) levels for whom baseline RBC FA data were available. Cox regression analysis was used to relate the risk of future events to RBC n-6 FA levels, both continuously and by quartile.
Results: At 7-year follow-up 183 (46.0%) had died, 128 (32.2%) had experienced another MI and 24 (6.0%) had had a stroke. Death or MI occurred in 227 patients (57.0%); and death, MI or stroke in 235 patients (59.0%). In a multivariable Cox regression model for total death, the hazard ratio (HR) in the highest as compared to the lowest quartile of dihomo-γ-linolenic acid (DGLA) was 0.55 [95% confidence interval (CI), 0.35-0.88, p= 0.012, for death or MI [HR 0.62 (95% CI, 0.41-0.94), p= 0.025], and for the fully combined endpoint [HR 0.57 (95% CI, 0.38-0.86), p= 0.006]. Similar results were found in the per 1-SD analysis. No other RBC n-6 FAs significantly predicted these outcomes in multivariable models.
Conclusions: RBC DGLA levels had significant independent prognostic value in post-ACS patients. These findings need confirmation, and the possible biochemical pathways by which higher DGLA membrane levels may be cardioprotective should be explored.