Thromboembolic episodes related to atrial arrhythmias in adults with transposition of great arteries

Background: Atrial arrhythmias (AA) are common in adults with congenital heart disease (ACHD). Although Intra-atrial Reentrant Tachycardia (IART) is well described in ACHD, Atrial Fibrillation (AF) is uncommon, but increasingly recognized. Patients with Transposition of the Great Arteries (TGA) and congenitally corrected-TGA (CC-TGA) have a high burden of AA at a relatively young age. However, long-term data of AA and associated thromboembolic risk are lacking in these patients. The prevalence, associated clinical factors, and complications of AA in a longitudinal TGA cohort was studied. Methods: A retrospective cohort study of all TGA patients from a single tertiary care centre was conducted. Data regarding documented atrial arrhythmias, thromboembolic events, and factors associated with thromboembolism were extracted and analyzed. Mean values and standard deviations were calculated for normally distributed continuous variables. When frequencies and means were compared, the chi-squared test and student t-test were used, respectively. Results: One-hundred twenty-five patients with TGA (76 TGA, 49 CC-TGA) were followed for a mean of 20.8 ± 13.2 years. AF was confirmed in 20% (n = 25) and there were 5 (20%) thromboembolic complications within the AF population. AF was associated with an annual thromboembolic event rate of 2.7%/year (stroke/transient ischemic attack 1.7%, systemic embolism 1.0%). Conclusion: AF is relatively common in the TGA ACHD population in long-term follow up. Although annual risk of thromboembolism is low in this young group of patients, life-time cumulative risk is potentially high. TGA patients should be screened actively for AF and appropriate anticoagulation therapy initiated. It is unclear if established risk prediction scores in other non-valvular AF populations may be applicable to this cohort.