An alpha-linolenic acid (ALA) rich diet in the Lyon Heart Study reduced sudden cardiac deaths possibly by reducing cardiac arrhythmias and ventricular fibrillation (Lancet 1994). Since then, there has been a growing interest in ALA as a cardioprotective nutrient. Much of the interest has focused on the potential antiarrhythmic effect of ω-3 fatty acids, especially the longer chain ω-3 fatty acids, DHA and EPA, derived from fish. We therefore concluded it important to test whether the shorter chain ω-3 vegetable oil ALA also had antiarrhythmic effects, since this might also explain the beneficial effects seen on cardiovascular mortality in the Lyon Heart Study.

Objective: We determined the effect of an ALA rich diet in reducing recurrence of atrial fibrillation as a further example of a cardiac arrhythmia.

Design: Randomized parallel design efficacy study. Setting: Three university hospital centers in the Bordeaux region, France. Patients: 98 successive patients successfully underwent electro cardioversion of whom 75 completed the study without major deviations according to the protocol.

Intervention: A canola margarine and oil together with a Mediterranean diet (ALA ω-3, 1.4 g/d) versus a conventional diet (control), with a one year follow-up.

Main outcome measure: Length of time to first recurrence of atrial fibrillation.

Significance: If ALA is antiarrhythmic this action may explain its cardioprotective effect in clinical trials and cohort studies.

Inclusion Criteria:

• patients hospitalized in one of the three centers in the Bordeaux region, and who subsequently underwent successful electrocardioversion for atrial fibrillation.

Exclusion Criteria:

• included patients who were unable to receive electrocardioversion or those who were already enrolled in another trial
• patients who were unable or unwilling to comply with the diet recommendations (experimental or control) or follow-up requirements
• patients with clinically significant cardiac disease, advanced heart failure, cardiac cachexia, thyroid disease, treated or untreated, clinically significant hepatic or renal disease or a history of malignant disease or alcohol abuse were not included
• Taking ALA rich foods or recording intakes of ALA >2g/d on the control diet or reporting using <1g/d on the ALA diet was considered a major deviation from the protocol.