Associations of the serum <i>n</i>-6 PUFA concentrations with exercise-induced myocardial ischaemia in middle-aged and older men

<i>n</i>-6 PUFA, especially linoleic acid (LA) but also arachidonic acid (AA), have been inversely associated with CHD. However, mechanisms underlying these associations are not fully known. We investigated the associations of the serum concentrations of total <i>n</i>-6 PUFA, LA, AA, <i>γ</i>-linolenic acid (GLA) and dihomo-<i>γ</i>-linolenic acid (DGLA), with the odds of myocardial ischaemia during exercise, a predictor of future cardiac events. A total of 1871 men without a history of CHD from the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) aged 42-60 years were included. All participants performed a maximal symptom-limited exercise stress test, using an electrically braked bicycle ergometer. Multivariable-adjusted logistic regression was used to assess the OR for exercise-induced myocardial ischaemia in quartiles of the serum <i>n</i>-6 PUFA concentrations. After multivariable adjustment, men in the highest <i>v</i>. the lowest serum AA concentration had 50 % lower odds for exercise-induced myocardial ischaemia (OR 0·50, 95 % CI 0·34, 0·76; <i>P</i>-trend across quartiles < 0·001). For the other PUFA, the OR (95 % CI) were 1·00 (0·69, 1·46; <i>P</i>-trend = 0·89) for LA, 1·07 (0·75, 1·53; <i>P</i>-trend = 0·40) for GLA and 0·74 (0·51, 1·07; <i>P</i>-trend = 0·16) for DGLA. Among the <i>n</i>-6 PUFA, higher serum concentration of AA was associated with lower odds for myocardial ischaemia during an exercise test in middle-aged and older men. This may provide one mechanism for the previously observed possible cardioprotective properties of AA. Our findings also suggest that <i>n</i>-6 PUFA should not be considered as one homogenous group.