Introduction Adults with congenital heart disease have a high burden of arrhythmias related to the underlying substrate, and the consequences of palliation. The NORPAP ACHD database, established in 1993, contains 2587 patients in 2 non-surgical centres.

Methodology Patients with documented arrhythmias were extracted from the NORPAP database and analysed for demographics, underlying condition, surgical intervention, rhythm, and electrophysiological (EP) procedures between 1993 and 2015.

Results 13.6% of patients (353/2587) had documented arrhythmia, mean age 51 years, 50% male, prior surgical intervention in 77.9%. Atrial tachyarrhythmias predominate: Atrial Fibrillation (AF) 35.6%, Atrial Flutter (AFL) 24.3%, Supraventricular tachycardia (SVT) 19.5% and Atrial Tachycardia (AT) 8.2%. It was common for patients to experience more than one episode and type of arrhythmia. High grade AV Block in 8.5%, Sinus Node Dysfunction 3.4%. Ventricular Tachycardia (VT) 9.9%, Ventricular Fibrillation 0.6%. 32% of patients with arrhythmias had EP procedures, 82.4% had prior surgical intervention. Of the total, 88 had RF Ablation; 18% required repeat procedures. Underlying condition was diverse (21 conditions): Secundum ASD 19/88 (21.6%), Fallot’s Tetralogy 19/88 (21.6%), and Ebstein’s anomaly 9/88 (10.2%) were the most common.

Conclusions Whilst arrhythmias are most common in Secundum ASD, complex ACHD (ccTGA, complex congenital, TGA and Ebstein’s anomaly) have a disproportionately high arrhythmia burden. 10% increase in EP procedures noted compared to our 2006 study. This is appropriate for to avoid recurrent admissions and long term anti-arrhythmics. Complex anatomy, challenging venous access and scar related re-entry tachycardias underline the need to expand the subspecialist EP-CHD capacity internationally.