Background: Arrhythmias are common after congenital heart disease (CHD) surgery, with ectopic atrial tachycardia (EAT) estimated to occur in 8-15% of patients. This study aimed to identify risk factors for the development of post-operative EAT in a large retrospective cohort of patients less than one year of age. In addition, the timing, treatment, and outcomes of post-operative EAT were evaluated. 

Methods: This was a single-center retrospective analysis of patients undergoing CHD surgery in the first year of life between January 2007 and July 2020. Patients who had an ICD-9 or ICD-10 code for supraventricular tachycardia were reviewed to identify those who had EAT. Additional patients were identified through medication administration records and subsequent chart review. Patients and congenital cardiac surgeries with post-operative EAT were compared to controls under one year of age that did not have EAT. 
 
Results: Out of 5,243 infant CHD surgeries, EAT developed in 129 (2.5%). Compared to controls, the EAT cohort was younger (median 7 vs 85 days, p<0.01), weighed less at time of surgery (3.3 vs 4.2 kg, p<0.01), and was more likely to have DiGeorge syndrome (7.7% vs 3.0%, p<0.01). By multivariate analysis, total anomalous pulmonary venous connection (TAPVC) repair (odds ratio [OR] 2.8; 95% confidence interval 1.5-5.2), DiGeorge syndrome (OR 2.4; 1.1-5.2), Society of Thoracic Surgeons-European Association for Cardio-Thoracic surgery (STAT) category ≥ 4 (OR 2.1; 1.0-4.4), and longer cardiopulmonary bypass times (OR 1.1; 1.0-1.2) were identified as independent risk factors for EAT. The onset of EAT occurred at a median of 9 days (IQR 5-14 days) after CHD surgery with antiarrhythmic medications started at a median of 10 days after surgery. Antiarrhythmic treatment was initiated in 109/129 patients (84%) with propranolol (71%) and amiodarone (24%) the most commonly used medications. Although 15 (11.6%) patients did not survive to hospital discharge, EAT was not directly implicated in any deaths.

Conclusion: This study examined a relatively large cohort of patients less than one year of age that underwent congenital cardiac surgery and developed post-operative EAT. Although the absolute number of EAT patients is high (129 patients), the incidence of EAT was only 2.5%, which is lower than the previously reported incidence of 8-15%. The median time to EAT diagnosis was 9 days after cardiac surgery, with TAPVC repair, DiGeorge syndrome, STAT category ≥ 4, and longer cardiopulmonary bypass times identified as independent risk factors for the development of EAT after congenital cardiac surgery in infancy. Understanding the risk factors and natural history of EAT can help alert providers to monitor closely for its development and to begin antiarrhythmic treatment when appropriate.