Associations of the serum long-chain omega-3 polyunsaturated fatty acids and hair mercury with heart rate-corrected QT and JT intervals in men: the Kuopio Ischaemic Heart Disease Risk Factor Study.

PURPOSE: Long-chain omega-3 polyunsaturated fatty acids (PUFA) from fish have been associated with risk of cardiovascular diseases (CVD), especially sudden cardiac death (SCD). Mercury exposure, mainly due fish consumption, has been associated with higher risk. However, the impact of PUFAs or mercury on the ventricular cardiac arrhythmias, which often precede SCD, is not completely known. We investigated the associations of the serum long-chain omega-3 PUFAs and hair mercury with ventricular repolarization, measured by heart rate-corrected QT and JT intervals (QTc and JTc, respectively).

METHODS: A total of 1411 men from the prospective, population-based Kuopio Ischaemic Heart Disease Risk Factor Study, aged 42-60 years and free of CVD in 1984-1989, were studied.

RESULTS: Serum long-chain omega-3 PUFA concentrations were inversely associated with QTc and JTc (multivariate-adjusted P trend across quartiles = 0.02 and 0.002, respectively) and, during the mean 22.9-year follow-up, with lower SCD risk. However, further adjustments for QTc, JTc or hair mercury did not attenuate the associations with SCD. Hair mercury was not associated with QTc, JTc or SCD risk, but it slightly attenuated the associations of the serum long-chain omega-3 PUFA with QTc and JTc.

CONCLUSIONS: Higher serum long-chain omega-3 PUFA concentrations, mainly a marker for fish consumption, were inversely associated with QTc and JTc in middle-aged and older men from Eastern Finland, but QTc or JTc did not attenuate the inverse associations of the long-chain omega-3 PUFA with SCD risk. This suggests that prevention of prolonged ventricular repolarization may not explain the inverse association of the long-chain omega-3 PUFA with SCD risk.