• Occurrence of appropriate ICD intervention (shock or antitachycardia pacing) for spontaneous ventricular tachyarrhythmias, or all-cause mortality
  

• All cause mortality (separately from ventricular tachyarrhythmia)
  
• Cardiac mortality
  
• Myocardial infarction
  
• All arrhythmic events as documented by the ICD Core laboratory
  
• Change in the prescription of antiarrhythmic drugs
  

Previous human observational studies and clinical trials provide strong indications that n-3 PUFA from fish can prevent cardiovascular disease. Striking is that these studies show a strong relation between n-3 PUFA and sudden death, but not between n-3 PUFA and non-fatal heart disease. Sudden death is one of the most common and often the first manifestation of coronary heart disease. The majority of sudden deaths are directly caused by acute ventricular arrhythmia. Our hypothesis is that n-3 PUFA prevents sudden death by suppressing life-threatening cardiac arrhythmia. Therefore, we investigate in a randomized controlled clinical trial whether supplemental intake of n-3 PUFA from fish can reduce the incidence of life-threatening cardiac arrhythmias. Our population consists of patients with an implantable cardioverter defibrillator (ICD), because this device records all arrhythmic events in a memory chip. As the ICD enables continuous monitoring of events in nonhospitalised patients, this population is very suitable for testing a possible antiarrhythmic effect of n-3 PUFA. The objective of the SOFA trial is to investigate the effect of fish oil on the incidence of recurrent ventricular arrhythmia in patients with an ICD. The SOFA is a randomised, parallel, placebo-controlled, double-blind intervention study which is currently being carried out in 26 cardiology centers in Europe. Five hundred forty six patients with an ICD are randomised to receive either 2g/d of fish oil or placebo oil for a period up to 12 months. The primary outcome is spontaneous ventricular tachyarrhythmias as detected by the ICD or all-cause mortality within 12 months.

Inclusion Criteria:

• ICD is capable of recording ECG strips for at least 10 of its (attempted) therapeutic interventions
• 18 years or older
• written informed consent

Exclusion Criteria:

• Primary prophylactic indication
• ICD implantation as a ‘bridge’ to heart transplantation
• Refractory supraventricular arrhythmias with rapid ventricular rates despite antiarrhythmic therapy
• a projected lifespan of less than 1 year
• participation in another trial (during or within 30 days before SOFA)
• use of any supplemental n-3 fatty acid during the last 3 months
• intake of more than 8g of n-3 fatty acids from fish per month as judged by a fish frequency questionnaire
• pregnant women and women of childbearing potential who do not use adequate contraception
• patients known to have a history of recent drug or alcohol abuse