Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patients with implantable defibrillators: a randomized controlled trial

JAMA. 2005 Jun 15;293(23):2884-91. doi: 10.1001/jama.293.23.2884.


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.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Defibrillators, Implantable*
  • Dietary Supplements
  • Double-Blind Method
  • Erythrocyte Membrane / metabolism
  • Fatty Acids, Omega-3 / blood
  • Fatty Acids, Omega-3 / pharmacology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Proportional Hazards Models
  • Prospective Studies
  • Risk
  • Survival Analysis
  • Tachycardia, Ventricular / prevention & control
  • Tachycardia, Ventricular / therapy*
  • Ventricular Fibrillation / prevention & control
  • Ventricular Fibrillation / therapy*


  • Fatty Acids, Omega-3