Atrial arrhythmias are the most common complication encountered in the growing and aging population with congenital heart disease (CHD). We assessed the types and patterns of atrial arrhythmias, associated factors, and age-related trends.

A multicenter cohort study enrolled 482 patients with CHD and atrial arrhythmias, age 32.0±18.0 years, 45.2% female, from 12 North American centers. Qualifying arrhythmias were classified by a blinded adjudicating committee.

The most common presenting arrhythmia was intra-atrial reentrant tachycardia (IART; 61.6%), followed by atrial fibrillation (AF; 28.8%), and focal atrial tachycardia (FAT; 9.5%). Patients with FAT were the youngest at presentation (23.6±18.5years) followed by IART (28.8±16.8years) and AF (41.0±17.2years), P<0.0001. The proportion of arrhythmias due to IART increased with CHD complexity from 47.2% to 62.1% to 67.0% in patients with simple, moderate, and complex defects, respectively (P=0.0013). AF comprised 9.3% of arrhythmias in patients <20years and increased with age to surpass IART as the most common arrhythmia in those ≥50years (51.2% versus 44.2%, P<0.0001). Older age [odd ratio (OR) 1.024 per year, 95% confidence interval (CI; 1.010, 1.039), P=0.001] and hypertension [OR 2.00, 95% CI (1.08, 3.71), P=0.029] were independently associated with AF. During a mean follow-up of 11.3±9.4years, the predominant arrhythmia pattern was paroxysmal in 62.3%, persistent in 28.2%, and permanent in 9.5%. Permanent atrial arrhythmias increased with age from 3.1% in patients <20years to 5.5%, 12.9%, and 22.6% in ages 20–35, 35–50, and ≥50years, respectively (P<0.0001).

IART is the most common presenting atrial arrhythmia in patients with CHD, with a predominantly paroxysmal pattern. However, as the population ages, atrial arrhythmias become increasingly permanent. AF surpasses IART as the most prevalent type of atrial arrhythmia over the age of 50 years.