Are Arrhythmias Adequately Incorporated into Studies on Long-Term Outcomes After the Fontan Operation?

Arrhythmias are common after the Fontan operation and increase risk of morbidity and mortality. Their impact on late outcomes remains poorly understood. Our objective was to assess whether long-term studies after the Fontan incorporated the impact of arrhythmia characteristics on outcome. We reviewed the literature since 2005 for studies evaluating the impact of multiple risk factors on long-term outcomes and mortality after the Fontan. Studies focusing only on one or two risk factors (including arrhythmias) and those with a mean follow-up < 10 years were excluded. Of the 17 studies analyzed, only six mentioned rhythm at follow-up. Nine lumped all arrhythmias (tachyarrhythmia, bradyarrhythmia, paced rhythm, early and late arrhythmia) into one single category. Only eight of the 17 studies reported the incidence of tachyarrhythmias in detail and only two studies described bradyarrhythmias in detail as sinus or atrioventricular (AV) node dysfunction subgroups. Five studies reported on treatment of tachyarrhythmias including Fontan revision surgeries, catheter ablation, pacemaker placement and or the use of antiarrhythmic drugs. However, only one included information on the impact of treatment on outcomes. Out of 15 studies that conducted a multivariate analysis of Fontan outcomes, arrhythmia was included in the univariate model in 14 and in the multivariate model in 9. Overall, we found most studies on late outcomes after the Fontan do not include rhythm and arrhythmia characteristics in data collection and analysis. Incorporating more granular rhythm information in large databases and in multivariate analyses will help better determine and contextualize the impact of arrhythmias on outcomes after the Fontan.