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Dietary linolenic acid and adjusted QT and JT intervals in the National Heart, Lung, and Blood Institute Family Heart study.

Djoussé L, Rautaharju PM, Hopkins PN, Whitsel EA, Arnett DK, Eckfeldt JH, Province MA, Ellison RC,

Section of Preventive Medicine & Epidemiology, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA. ldjousse@bu.edu

OBJECTIVES: The goal of this study was to examine whether higher consumption of total linolenic acid was associated with rate-adjusted QT and JT intervals (QTrr and JTrr, respectively). BACKGROUND: Higher intake of fish omega-3 fatty acids and plant omega-3 such as alpha-linolenic acid is associated with lower risk of myocardial infarction. While long-chain omega-3 can inhibit ventricular arrhythmia, it is not known whether alpha-linolenic acid influences ventricular repolarization. METHODS: We studied 3,642 subjects from the National Heart, Lung, and Blood Institute Family Heart study who were free of myocardial infarction, left ventricular hypertrophy, pacemaker, and with QRS <120 ms. We used the 95th percentile of the gender-specific distribution of QTrr and JTrr to define abnormally prolonged repolarization. Within each gender, we created age- and energy-adjusted tertiles of linolenic acid and used regression models for analyses. RESULTS: Mean age was 50 years, and average intake of total linolenic acid was 0.74 g/day. There was an inverse association between consumption of linolenic acid and QTrr and JTrr (p for trend 0.001 and 0.0005, respectively). From the lowest (reference) to the highest gender-, age-, and energy-adjusted tertile of linolenic acid, multivariable adjusted odds ratios for prolonged QTrr were 1.0, 0.74 (95% confidence interval [CI] 0.57 to 0.96), and 0.59 (95% CI 0.44 to 0.77), respectively (p for trend 0.0003). Corresponding values for JTrr were 1.0, 0.73 (95% CI 0.52 to 1.03), and 0.59 (95% CI 0.40 to 0.87), respectively (p for trend 0.009). Exclusion of subjects taking drugs known to influence QT did not influence this association. CONCLUSIONS: Higher intake of dietary linolenic acid might be associated with a reduced risk of abnormally prolonged repolarization in men and women.

Published 16 May 2005 in J Am Coll Cardiol, 45(10): 1716-22.
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