Background: Atrial fibrillation (AF) is a prevalent diagnosis among individuals with interatrial shunts, and the prevalence increases with age (1). Since the 1990s, interventionists have introduced transcatheter techniques, to close interatrial shunts, while surgical procedures reserved in cases of technical complexity (2). Despite the potential reduction in AF incidence post interatrial shunt closure, discernible modifications in the cardiac conduction system may persist (3). Notwithstanding, reports indicate an incidence of new-onset AF in approximately 10-25% of patients after interatrial shunt closure, with a pronounced prevalence among elderly (4). This study aims to delineate the incidence of AF subsequent to interatrial shunt, surgical och transcatheter, closure within a national cohort in Sweden.

Methods: The study includes all patients diagnosed with an interatrial shunt, atrial septal defect and patent foramen ovale, classified using the International Classification of Diseases, 10th edition (ICD-10), as documented in the Swedish National Patient Register, along with data sourced from the Cause of Death Register. Patients with multiple diagnoses of other congenital heart diseases are excluded, and interventions performed between 1997 and 2017 are identified using the NOMESCO surgical classification. Comorbidities such as chronic ischemic heart disease, myocardial infarction, heart failure, hypertension, and diabetes are considered, with the primary endpoint being the incidence of AF post-intervention.

Results: A total of 3,426 patients with interatrial shunts underwent intervention between 1997 and 2017, with a mean follow-up duration of 6.2 years. Among these, 49%(n=1,725) underwent transcatheter closure, while 41 patients underwent both transcatheter and surgical procedures. The mean age was 36 years, with 9% presenting with heart failure at baseline. Before the intervention, 14% (n=483) had AF, increasing to 22% (n=755) post-intervention. Of those developing AF post-intervention, 16% (n=119) experienced the AF event within 60 days, evenly distributed between transcatheter and surgical procedures. Over 40% of patients with post-intervention AF had an average age of 62. The incidence of AF post-intervention was 1.6 per 100 patient-years (see Figure). Stroke incidence was 3.6 per 100 patient-years and the mortality rate was 7% (n=257) during follow up (see Table). Conclusions: Patients with interatrial shunts exhibit a high incidence of AF, which further escalates following closure of the interatrial shunt, not only within the first few days post-intervention, particularly among the elderly population. This can relate to high incidence of ischemic stroke. © The Author(s) 2024.