Fish oil risky to defribillator patients

[ozzman]

I recently ran into this article and figured it would be a good warning. I will quote the article and the actual abstract from the JAMA.

Fish Oil Supplements May Be Risky to Defibrillator Patients


By Tom Ewing, MedPage Today Staff Writer
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
June 15, 2005
Also covered by: Forbes, MSN, USA Today
MedPage Today Action Points

* Recognize that dietary supplementation with fish oil may increase the risk for serious heart rhythm problems in patients with implanted cardioverter defibrillators.

* Understand that the results of this study do not call into question the potential benefits of fish oil supplementation in patients who have had a myocardial infarction.

Review
PORTLAND, Ore., June 15-Fish oil supplements apparently increase the risk of ventricular arrhythmias in patients with implantable cardioverter defibrillators, researchers here reported.

Even though earlier studies have shown that fatty acids from fish oil reduced the risk of sudden cardiac death, this study found that a diet supplemented with omega-3 polyunsaturated fatty acids (PUFAs) did not help patients with defibrillators, according to a study published in the June 15 issue of the Journal of the American Medical Association.

The lack of benefit and the suggestion that fish oil supplementation may increase the risk of ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients with defibrillators "can reasonably be interpreted as evidence that fish oil supplementation in these patients who have recurrent ventricular arrhythmias should be avoided," wrote Merritt Raitt, M.D., and colleagues at Oregon Health and Science University here.

Previous trials have shown that dietary changes or supplements to increase omega-3 PUFA intake resulted in a reduced risk of sudden death without a consistent change in risk of myocardial infarction.

So the investigators undertook a prospective, double-blind, randomized, placebo-controlled trial of fish oil supplementation in patients with a recent episode of sustained ventricular arrhythmia. Included in the study were 200 participants with implanted defibrillators.

Patients taking class I or class III antiarrhythmic medications were excluded, as were patients who consumed more than one fatty acid (salmon, Chilean sea bass, sardine, herring, or mackerel) meal per week or who had taken flaxseed, cod liver oil, or fish oil supplements in the previous month.

For the study, the patients were randomly assigned to receive supplements of fish oil, 1.8 g/d, 72% omega-3 PUFAs, or placebo and were followed up for a median of 718 days. The researchers found:

* Patients randomized to receive fish oil had an increase in the mean percentage of omega-3 PUFAs in red blood cell membranes from 4.7% to 8.3% (P <.001), with no change observed in patients receiving placebo.

* At six, 12, and 24 months, 46% (SE, 5%), 51% (5%), and 65% (5%) of patients randomized to receive fish oil had ICD therapy for VT/VF, compared with 36% (5%), 41% (5%) and 59% (5%) for patients randomized to receive placebo (P = .19).

* In the subset of 133 patients whose qualifying arrhythmia was VT, 62% (SE, 6%), 66% (6%) and 79% (6%) of patients in the fish oil group had VT/VF at six, 12, and 24 months, compared with 37% (6%), 43% (6%), and 65% (6%) of patients in the control group (P = .007).

* Recurrent VT/VF events were more common in patients randomized to receive fish oil (P = .001).

The researchers concluded that, among patients with a recent episode of sustained ventricular arrhythmia and an implanted defibrillator, fish oil supplementation does not reduce the risk of VT/VF.

"In fact," they wrote, "the trend toward a higher incidence of VT/VF occurrence with fish oil supplementation, the significant increase in VT/VF occurrence with VT as the qualifying entry rhythm, and the increased rate of recurrent episodes of VT/VF in patients assigned to fish oil suggest that fish oil may be proarrhythmic in this population."

The researchers noted that their study was undertaken to better understand the previously observed reduction in sudden death mortality after myocardial infarction associated with fish oil supplementation.

"The fact that we were not able to demonstrate an antiarrhythmic effect of fish oil does not call into question the potential benefits of fish oil or dietary fish intake in patients who have had a myocardial infarction," they wrote.

"Instead, our results suggest that the mechanisms of benefit, if due to antiarrhythmic properties, may not be due to the suppression of reentrant VT or VF."

Related article:

* Dietary Soy and Fish Oil Work Quickly to Improve Cardiac Function

Primary source: Journal of the American Medical Association
Source reference:
Raitt M, et al. Fish Oil Supplementation and Risk of Ventricular Tachycardia and Ventricular Fibrillation in Patients with Implantable Defibrillators. JAMA. 2005;293:2884-2891

Fish Oil Supplementation and Risk of Ventricular Tachycardia and Ventricular Fibrillation in Patients With Implantable Defibrillators

A Randomized Controlled Trial

Merritt H. Raitt, MD; William E. Connor, MD; Cynthia Morris, PhD, MPH; Jack Kron, MD; Blair Halperin, MD; Sumeet S. Chugh, MD; James McClelland, MD; James Cook, MD; Karen MacMurdy, MD; Robert Swenson, MD; Sonja L. Connor; Glenn Gerhard, MD; Dale F. Kraemer, PhD; Daniel Oseran, MD; Christy Marchant, RN, MBA; David Calhoun, RN; Reed Shnider, MD; John McAnulty, MD

JAMA. 2005;293:2884-2891.

Context Clinical studies of omega-3 polyunsaturated fatty acids (PUFAs) have shown a reduction in sudden cardiac death, suggesting that omega-3 PUFAs may have antiarrhythmic effects.

Objective To determine whether omega-3 PUFAs have beneficial antiarrhythmic effects in patients with a history of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF).

Design and Setting Randomized, double-blind, placebo-controlled trial performed at 6 US medical centers with enrollment from February 1999 until January 2003.

Patients Two hundred patients with an implantable cardioverter defibrillator (ICD) and a recent episode of sustained VT or VF.

Intervention Patients were randomly assigned to receive fish oil, 1.8 g/d, 72% omega-3 PUFAs, or placebo and were followed up for a median of 718 days (range, 20-828 days).

Main Outcome Measures Time to first episode of ICD treatment for VT/VF, changes in red blood cell concentrations of omega-3 PUFAs, frequency of recurrent VT/VF events, and predetermined subgroup analyses.

Results Patients randomized to receive fish oil had an increase in the mean percentage of omega-3 PUFAs in red blood cell membranes from 4.7% to 8.3% (P<.001), with no change observed in patients receiving placebo. At 6, 12, and 24 months, 46% (SE, 5%), 51% (5%), and 65% (5%) of patients randomized to receive fish oil had ICD therapy for VT/VF compared with 36% (5%), 41% (5%), and 59% (5%) for patients randomized to receive placebo (P = .19). In the subset of 133 patients whose qualifying arrhythmia was VT, 61% (SE, 6%), 66% (6%), and 79% (6%) of patients in the fish oil group had VT/VF at 6, 12, and 24 months compared with 37% (6%), 43% (6%), and 65% (6%) of patients in the control group (P = .007). Recurrent VT/VF events were more common in patients randomized to receive fish oil (P<.001).

Conclusion Among patients with a recent episode of sustained ventricular arrhythmia and an ICD, fish oil supplementation does not reduce the risk of VT/VF and may be proarrhythmic in some patients.


Author Affiliations: Oregon Health and Science University, Portland (Drs Raitt, Connor, Morris, Kron, Chugh, MacMurdy, Gerhard, Kraemer, and McAnulty, Mss Connor and Marchant, and Mr Calhoun), Portland VA Medical Center (Drs Raitt and MacMurdy), St Vincent Medical Center (Drs Halperin and Oseran), and Oregon State University (Dr Kraemer), Portland; Sacred Heart Medical Center, Eugene, Ore (Dr McClelland); Southwest Medical Center, Vancouver, Wash (Dr Swenson); and Baystate Medical Center, Springfield, Mass (Drs Cook and Shnider).

This is my PSA for the month.

ozzman