Background: Atrial arrhythmias are a major cause of morbidity and mortality in adults with Fontan palliation. Left atrial volume using various methods, has been shown to be a strong predictor of outcomes including sustained atrial arrhythmia (SAA) in various acquired heart disease. There is little data regarding atrial volume and association with atrial arrhythmias in adults with Fontan palliation.
Objective: We sought to determine if adults with Fontan palliations and sustained atrial arrhythmias have increased atrial volume.
Methods: This is a single center retrospective case matched control study. Cases were defined as patients with Fontan palliation, > 18 years of age, with SAA requiring cardioversion, ablation procedure, or intravenous anti-arrhythmic medication, who also had advanced imaging with cardiac MRI or CT angiography (2013 - present). Age matched controls were selected from patients with Fontan palliation and no history of SAA who had MRI or CT. A combined atrial volume (CAV) assessment was performed from MRI or CT scan, including left and right atrial volume due to unrestrictive atrial septum, but excluding Fontan baffle. Statistical analysis was performed using Student’s t-test.
Results: Fifteen case patients and 16 age-matched controls with Fontan palliation were identified. Mean age of patients with SAA was 32±10.7 years compared to controls with mean age 27.7±3.8 years. The majority of patients in both groups had lateral tunnel Fontan, 11/15 (73%) in SAA group compared to 13/16 (81%) in control group, the remainder were extracardiac. Indexed CAV was significantly higher in SAA patients (92.4±49.3 mL/kg) compared to controls (58.1±16.4 mL/kg, p = 0.007). All control patients had CAV ≤ 90 mL/kg. Six out of 15 (40%) patients in SAA group had at least one cardioversion and 10/15 (67%) patients had an EP study. Six out of 10 (60%) patients in SAA group demonstrated multiple atrial tachyarrhythmias at the time of EP study.
Conclusion: SAA in adults with Fontan palliation, either lateral tunnel or extracardiac, is associated with significantly larger CAV assessed by MRI or CT. CAV ≥ 90 mL/kg may be a valuable marker for SAA risk in adults with Fontan palliation, warranting increased arrhythmia monitoring.