Fish Oil Inhibits Sustained Ventricular Tachycardia

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Fish Oil Inhibits Sustained Ventricular Tachycardia

Laurie Barclay, MD

Medscape Medical News 2004. C 2004 Medscape

April 30, 2004 - An infusion of n-3 polyunsaturated fatty acids (PUFA) had

immediate inhibitory effects on sustained ventricular tachycardia, according

to the results of a pilot study published in the May 1 issue of The Lancet.

" Increased consumption of n-3 fatty acids reduces mortality from sudden

cardiac death, indicating that such acids have anti-arrhythmic effects, "

write Rainer Schrepf, from Kardiologie Medizinische Poliklinik in Munich,

Germany, and colleagues. " Our findings show that infusion of n-3

polyunsaturated fatty acids does not induce arrhythmia, but did result in a

reduction of sustained ventricular tachycardia in some patients. "

The investigators performed electrophysiological testing in 10 patients with

implanted cardioverter defibrillators who were at high risk of sudden

cardiac death.

In seven of the 10 patients, sustained monomorphic ventricular tachycardia

was inducible at baseline. After infusion of n-3 PUFA in the seven inducible

patients, monomorphic sustained ventricular tachycardia could no longer be

induced in five patients. One of the remaining patients was still inducible,

and the other was induced only after a more aggressive stimulation (three

rather than two extra stimuli).

Limitations of this pilot study include the small number of patients, the

absence of randomization, and the absence of a placebo group.

" The results indicate that infusion of n-3 PUFA does not induce arrhythmia.

By contrast, induction of sustained ventricular tachycardia was reduced in

five of seven patients after infusion of n-3 PUFA, " the authors write.

" These preliminary findings require confirmation in blinded,

placebo-controlled, randomised trials before definitive conclusions about

the anti-arrhythmic effects of n-3 PUFA in human beings can be drawn. "

Dr. Schrepf has given lectures sponsored by Medtronic, St. Jude Medical, and

Guidant. Another author has given lectures sponsored by Fresenius-Kabi and

Orthomol GmbH.

In an accompanying editorial, Albert, from Massachusetts General

Hospital in Boston, reviews the data on cardiovascular risk reduction

related to fish consumption.

" As has been shown with traditional anti-arrhythmic drugs, suppression of

ventricular tachycardia during electrophysiological testing does not

directly translate into a survival benefit when the same drugs are

administered chronically, " she writes. " Therefore the implications of these

data on their own, in conjunction with previous experimental data, provide a

possible mechanism to explain the preferential benefit seen with dietary

intake of n-3 fatty acids on sudden cardiac death in the earlier

observational studies and randomized trials. "

Dr. Albert recommends confirmation of these preliminary data in randomized

trials with hard arrhythmic end points in combination with mortality, and

she notes that three randomized trials of the effect of fish-oil

supplementation on recurrent episodes of ventricular tachycardia and/or

fibrillation are ongoing.

" If these and other trials confirm the anti-arrhythmic properties of these

n-3 acids, fish oil might become a less toxic and more appetizing

alternative to traditional anti-arrhythmic drugs, " she concludes.