Atrial Fibrillation Is an Independent Risk Factor for Ventricular Fibrillation A Large-Scale Population-Based Case-Control Study

Background —Atrial Fibrillation (AF) is associated with sudden cardiac death (SCD). We aimed to study whether AF is associated with ventricular fibrillation (VF), the most common cause of SCD, and whether this association is independent of confounders, i.e., concomitant disease, use of antiarrhythmic or QT-prolonging drugs, and acute myocardial infarction (AMI). Methods and Results —We performed a community-based case-control study. Cases were patients with out-of-hospital cardiac arrest due to ECG-documented VF. Controls were age/sex-matched non-VF subjects from the community. VF risk in AF patients was studied by means of (conditional) logistic regression, adjusting for all available confounders. We studied 1397 VF cases and 3474 controls. AF occurred in 215 cases (15.4%) and 90 controls (2.6%). AF was associated with a three-fold increased risk for VF (adjusted OR 3.1 [2.1-4.5]). VF risk in AF cases was increased to the same extent across all age/sex groups, and in AF cases who had no comorbidity (adjusted OR 3.0 [1.6-5.5]) or used no confounding drugs (antiarrhythmics: 2.4 [1.4-4.3], QT-prolonging drugs: 3.1 [1.8-5.4]). VF risk was similarly increased in AF cases with AMI-related VF (adjusted OR 2.6 [1.4-4.8]), and those with non-AMI-related VF (adjusted OR 4.3 [1.9-10.1]). Conclusions —AF is independently associated with a three-fold increased risk for VF. Co-morbidity, use of antiarrhythmic or QT-prolonging drugs, or AMI does not fully account for this increased risk.