P-343: No effects of alpha-linolenic acid and linoleic acid on QTC duration in a high cardiovascular risk group

Background The positive effect of the n-3 fatty acid alpha-linolenic acid (ALA) on mortality after myocardial infarction has well been established. An anti-arrhythmogenic effect by changes in membrane composition and cardiac autonomic function has been suggested as a possible mechanism. We compared the effect of ALA and linoleic acid (LA) on n-3/n-6 poly-unsaturated fatty acids (PUFA) content of the serum cholesteryl ester and QTc duration in a high cardiovascular risk group in a primairy prevention setting. Methods and materials Eligible subjects had a serum total cholesterol of 6-8 mmol/l and at least two other risk factors (smoking, hypertension, overweight, family history of cardiovascular disease). They were randomized to free supply of ALA (n=36) or LA (n=38) enriched margarine during 2 years. All received nutritional education. A standard 12-leads ECG was recorded. QT duration was adjusted for heart-rate using Bazett's formula (QTc=QT/RR0.5). Data are shown as mean±SEM. Results (See Table) ALA-base ALA-2years LA-base LA-2years Sex M/F (n) 14/24 . 13/23 . Age (years) 53.9 (1.6) . 54.7 (1.6) . serum total cholesterol 6.6 (0.1)* 6.5 (0.1) 6.9 (0.1)*# 6.4 (0.1)# BMI (kg/m) 30.3 (0.6)## 30.9 (0.7)## 29.7 (0.6)# 30.4 (0.7)# n-3 PUFA 2.3 (0.2)# 3.2 (0.2)*# 2.2 (0.1) 2.5 (0.2)* n-6 PUFA 63.4 (0.7) 63.1 (0.6) 62.0 (0.7) 62.7 (1.0) n-6/n-3 ratio 33.2 (2.3)# 22.5 (1.7)**# 31.9 (1.8) 28.8 (1.6)** QTc duration (ms) 418 (3) 418 (4) 414 (2) 416 (3) ΔQTc (ms) . -0.9 (2.6) . 1.9 (2.9) *p