Consumption Of Fish Oil Does Not Appear To Protect Against Abnormal Heart Rhythms

Patients with an implantable cardioverter defibrillator did not have a significantly lower risk of serious abnormal heart rhythms or death by consuming fish oil supplements, which had been thought to have a protective effect.

19/06/06 Patients with an implantable cardioverter defibrillator did not have a significantly lower risk of serious abnormal heart rhythms or death by consuming fish oil supplements, which had been thought to have a protective effect, according to a study in the June 14 issue of JAMA.

Sudden cardiac death is responsible for approximately 50 percent of all death from cardiovascular disease in the Western world. Epidemiological studies indicate that intake of very-long-chain n-3 polyunsaturated fatty acids (omega-3 PUFAs) as present in fish or fish oil is associated with a reduction in cardiovascular death, possibly by reducing susceptibility to cardiac arrhythmia, according to background information in the article. Recent trials on fish oil and ventricular arrhythmia (abnormal heart rhythm) in patients with implantable cardioverter defibrillators (ICDs; an electrical device that can correct an abnormal heart rhythm) yielded inconclusive results.

Ingeborg A. Brouwer, Ph.D., of Wageningen University, the Netherlands, and colleagues tested the effect of omega-3 PUFAs from fish on the incidence of recurrent ventricular arrhythmia and all-cause death in a large, placebo-controlled, randomized trial of patients with ICDs. The Study on Omega-3 Fatty acids and ventricular Arrhythmia (SOFA) was conducted at 26 cardiology clinics across Europe and included 546 patients with ICDs and prior documented ventricular tachycardia (VT) or ventricular fibrillation (VF) (both are types of serious cardiac arrhythmias). Patients were randomly assigned to receive 2 grams/day of fish oil in capsules (n equals 273) or placebo capsules (n equals 273) for a median (midpoint) period of 356 days.

In total, 75 patients (27 percent) in the fish oil group and 81 patients (30 percent) in the placebo group received appropriate ICD intervention for VT or VF. Event-free survival did not substantially improve in the fish oil group. "In this large randomized trial we did not find evidence of strong protective effect of intake of omega-3 PUFAs from fish oil against ventricular arrhythmia in patients with ICDs. In contrast to others, we did not find that fish oil may have proarrhythmic properties," the authors conclude.