Evolving electroanatomic substrate and intra-atrial reentrant tachycardia late after Fontan surgery.
BACKGROUND
The prevalence of intra-atrial reentrant tachycardia (IART) increases with age in Fontan patients. This study aimed to characterize the atrial electroanatomic substrate for IART late after Fontan surgery.


RESULTS
Detailed electroanatomic mapping of the right atrium (RA) was performed in 11 consecutive patients (33 ± 9 years) with older style Fontan circulation (atriopulmonary and atrioventricular connection) who underwent their first radiofrequency catheter ablation (RFCA) for IART. A comparative group of 30 non-Fontan congenital heart disease (CHD) patients were also studied. Fontan patients had larger RA (P = 0.004), larger low-voltage area ≤ 0.5 mV (P = 0.01), and more fractionated potentials (P < 0.001) than non-Fontan CHD patients. RA enlargement correlated significantly with both low-voltage zones (Spearman ρ= 0.68, P < 0.001) and fractionated potentials (Spearman ρ= 0.48, P = 0.001). Among Fontan patients, both age and time since Fontan surgery were significantly correlated to the amount of low-voltage areas (Spearman ρ= 0.87, P < 0.001; Spearman ρ= 0.63, P = 0.04, respectively). Successful RFCA was accomplished in 30 (73%) patients and was less likely in Fontan patients (54% vs 83%, P = 0.04). Larger RA was significantly associated with a lower success rate (P = 0.04). During a follow-up duration of 2.3 ± 1.6 years, IART recurred in 47% of patients. Larger RA size and larger low-voltage areas predicted IART recurrence after RFCA.


CONCLUSIONS
Fontan patients demonstrate progressive adverse atrial electrical remodeling with increasing age and time since surgery. Newer strategies beyond surgical incisions, such as pharmacotherapies that retard the progression of atrial fibrosis, may be required to reduce the long-term risk of atrial arrhythmias.
Division of Cardiology, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.
Sing-Chien
SC
Yap
Louise
L
Harris
Eugene
E
Downar
Kumaraswamy
K
Nanthakumar
Candice K
CK
Silversides
Vijay S
VS
Chauhan
D000200:Action Potentials; D000328:Adult; D000367:Age Factors; D016022:Case-Control Studies; D017115:Catheter Ablation; D016009:Chi-Square Distribution; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D018729:Fontan Procedure / Q000009:adverse effects*; D006325:Heart Atria / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D009864:Ontario; D016016:Proportional Hazards Models; D012008:Recurrence; D018570:Risk Assessment; D012307:Risk Factors; D013617:Tachycardia, Supraventricular / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome; D056969:Voltage-Sensitive Dye Imaging; D055815:Young Adult