Archief Roodbont

Fish oils do not prevent arrhythmia

7 January 2009

MedWire News: Dietary supplementation with fish oils is associated with reduced cardiac related deaths but has no effect on the incidence of arrhythmias, indicate meta-analysis findings published online in the British Medical Journal.

Ross Tsuyuki (University of Alberta, Edmonton, Canada) and colleagues systematically examined the association between fish oil supplementation and arrhythmic events.

The meta-analysis included 12 studies and some 32,779 participants, 92% of whom were involved in two trials: the GISSI Prevenzione trial including 11,324 patients randomized to a mixture of the omega 3 fats eicosapentaeonic acid (EPA) and docosahexaenoic acid (DHA) in a 1.2:1 ratio or placebo; and the Japan EPA Lipid Intervention study (JELIS) which included 18,645 patients with hypercholesterolemia randomized to EPA or placebo.

The GISSI trial in particular sparked interest in the potential antiarrythmic properties of fish oils (specifically n-3 polyunsaturated fatty acids, or omega 3 fats), note the researchers, as the reduction in all-cause mortality and cardiovascular death seen in that trial seemed to be driven by a reduction in sudden cardiac death.

Tsuyuki and co-workers report that in three studies including 1148 patients with ICDs, the risk for appropriate ICD intervention was a nonsignificant 10% lower in those taking fish oil supplement than those on placebo.

And there was a nonsignificant 19% lower odds for sudden cardiac death in six studies, totaling 31,111 patients, that looked at this endpoint.

Meanwhile death from cardiac causes was reduced significantly, by 20%, in individuals taking fish oils compared with those not in eleven studies. All-cause mortality was reduced by a nonsignificant 8% among people taking fish oils in the eleven studies evaluating this endpoint.

The authors note that the results were driven primarily by the GISSI-Prevenzione and JELIS trials.

Further analysis failed to find any evidence for a dose-response relationship between DHA and EPA and death from cardiac causes. “Therefore, an ideal formulation for fish-oil supplementation cannot be determined with the currently available evidence,” the authors write.

Subgroup analysis in patients with coronary heart disease revealed a significant 26% reduction in sudden cardiac death (in four trials) and significant 20% reduction in cardiac deaths (in eight trials) with fish oil compared with placebo.

Eric Brunner (University College London, UK) and Hiroyasu Iso (Osaka University, Japan) noted in a related editorial that there was a 20% reduction in nonfatal coronary endpoints, driven by reduced unstable angina, but no effect on fatal outcomes with fish oil in JELIS.

Although they point out that JELIS may have been underpowered to detect effects on fatal endpoints, they commented: “This evidence challenges the proposition, supported by the dramatic reduction in deaths from cardiac disease in a subgroup analysis of GISSI, that the effect of fish oil is mainly the result of electrical stabilization of the myocardium.”

Br Med J 2009; Advance online publication