Abstract 2026: Atrial Fibrillation Predicts Ventricular Arrhythmogenicity In Heart Failure

Background: Atrial fibrillation (AF) is associated with appropriate ICD discharges in patients with primary prevention indications. We explored potential effect modifiers impacting on ventricular arrhythmogenic risk associated with AF. Methods and Results: A retrospective cohort study was conducted on 215 consecutive patients with ICDs for primary prevention having a left ventricular ejection fraction (LVEF) 35% and followed for 1.3±0.7 years. Mean age was 61.0±0.7 years and 17% were women. Cox regression models were explored in subgroups of patients stratified by demographic parameters, prior medical and surgical history, physical exam features, laboratory findings, and results of diagnostic tests. Appropriate ICD discharges were received by 10% of patients. AF was associated with a 3.5 fold increased risk [95% CI (1,5, 8.1), P=0.005]. Effect modifiers for the relationship between AF and appropriate ICD discharges included QRS duration and QTc. In patients with a QRS>130 msec (N=93), 6 of 33 (18%) patients with AF received appropriate ICD discharges versus 2 of 60 (3%) without AF (P=0.03). In this subgroup, AF was associated with a hazard ratio of 5.1 (P=0.049). Among individuals with a QTc >440 msec (N=93), 6 of 32 (19%) AF patients received appropriate ICD discharges versus 1 of 61 (2%) without AF (P=0.01). AF was associated with a hazard ratio of 10.3 (P=0.031). Five of 28 patients (18%) with both prolonged QRS and QTc duration (N=77) that also having AF received appropriate ICD discharges compared to 0 of 49 of patients without AF (P=0.005). After adjusting for medical therapy, AF independently predicted appropriate ICD discharges in subgroups with and without QRS and QTc increase. Conclusion: AF portends increased risk for ventricular tachyarrhythmias in patients with heart failure, particularly when associated with conduction and/or repolarization abnormalities. This finding may reflect common depolarization and repolarization defects associated with the arrhythmic milieu contributing to AF and ventricular arrhythmias, or adverse consequences of AF on the complex neurohumoral/electrophysiological substrate underlying ventricular arrhythmogenesis in heart failure.