Dihomo-gamma-linolenic acid (DGLA) is an n-6
polyunsaturated fatty acid (PUFA) derived from
linoleic acid (LA). The LA:DGLA ratio reflects conversion from LA to DGLA. Low levels of DGLA in serum have been related to poor outcome in
myocardial infarction (MI) patients. Aims: To assess the association of DGLA and LA:DGLA with total death as a primary aim and incident cardiovascular events as a secondary objective. Methods: Baseline samples from 1002 patients, aged 70 to 82 years, included 2-8 weeks after an MI and followed for 2 years, were used. Major adverse clinical events (
MACE) consisted of nonfatal MI, unscheduled coronary revascularization,
stroke, hospitalization for
heart failure or all-cause death. Cox regression analysis was used to relate serum n-6 PUFA
phospholipid levels (%wt) to the risk of
MACE, adjusting for the following: (1) age, sex and body mass index (BMI); (2) adding baseline
cod liver oil supplementation; (3) adding prevalent
hypertension,
chronic kidney disease and
diabetes mellitus. Results: Median DGLA level in serum
phospholipids was 2.89 (Q1-Q3 2.43-3.38) %wt. DGLA was inversely related to LA and LA:DGLA ratio. There were 208 incident cases of
MACE and 55 deaths. In the multivariable analysis, the hazard ratio (HR) for the total death in the three higher quartiles (Q2-4) of DGLA as compared to Q1 was 0.54 (0.31-0.95), with p = 0.03 (Model-1), 0.50 (0.28-0.91), with p = 0.02 (Model-2), and 0.47 (0.26-0.84), with p = 0.012 (Model-3), and non-significant for
MACE. Risk of
MACE (Model 3) approached borderline significance for LA:DGLA in Q2-4 vs. Q1 [HR 1.42 (1.00-2.04), p = 0.052]. Conclusions: Low levels of DGLA were related to a high LA:DGLA ratio and risk of total death in elderly patients with recent MI.