Extravirgin Olive Oil Consumption Reduces Risk of Atrial Fibrillation

Background— The PREDIMED (Prevención con Dieta Mediterránea) primary prevention trial showed that a Mediterranean diet enriched with either extravirgin olive oil or mixed nuts reduces the incidence of stroke, myocardial infarction, and cardiovascular mortality. We assessed the effect of these diets on the incidence of atrial fibrillation in the PREDIMED trial. Methods and Results— Participants were randomly assigned to 1 of 3 diets: Mediterranean diet supplemented with extravirgin olive oil, Mediterranean diet supplemented with mixed nuts, or advice to follow a low-fat diet (control group). Some departures from individual randomization occurred in a subset of the trial because members of the same household and small clinics in one of the 11 recruiting centers were allocated by clusters instead of individually. Incident atrial fibrillation was adjudicated during follow-up by an events committee blinded to dietary group allocation. Among 6705 participants without prevalent atrial fibrillation at randomization, we observed 72 new cases of atrial fibrillation in the Mediterranean diet with extravirgin olive oil group, 92 in the Mediterranean diet with mixed nuts group, and 89 in the control group after median follow-up of 4.7 years. The Mediterranean diet with extravirgin olive oil significantly reduced the risk of atrial fibrillation (hazard ratio, 0.62; 95% confidence interval, 0.45–0.86 compared with the control group) after adjusting for propensity scores and using robust variance estimators to account for the intra-cluster correlations. No effect was found for the Mediterranean diet with nuts (hazard ratio, 0.86; 95% confidence interval, 0.63–1.16). In secondary analyses done after excluding all participants randomized in clusters, the results did not materially change. Conclusions— In the absence of proven interventions for the primary prevention of atrial fibrillation, this post hoc analysis of the PREDIMED trial suggests that a lower incidence of atrial fibrillation was found after an intervention with extravirgin olive oil in the context of a Mediterranean dietary pattern. Clinical Trial Registration— URL: http://www.controlled-trials.com . Unique identifier: ISRCTN35739639.