Contemporary Patients with Congenital Heart Disease: Uniform Atrial Tachycardia Substrates Allow for Clear Ablation Endpoints with Improved Long-Term Outcome

Background: Poor outcome after atrial tachycardia (AT) radiofrequency catheter ablation (RFCA) in repaired congenital heart disease (CHD) has been attributed to CHD complexity. This may not apply to contemporary patients. The objective of our study was to assess outcome after RFCA for AT in contemporary patients with CHD according to prior atrial surgery and predefined procedural endpoints. Methods: Patients with CHD referred for AT RFCA to 3 European centers were classified as no atrial surgery/cannulation only, limited or extensive prior atrial surgery. Procedural success was predefined as termination and nonreinducibility for focal AT and bidirectional block across ablation lines for intra-atrial reentrant tachycardia and after empirical substrate ablation for noninducible patients. Patients were followed for AT recurrence and mortality. Results: Ablation was performed in 290 patients (41±17 years, 59% male; 3-dimensional mapping 89%, irrigated tip catheters 90%, transbaffle access 15%). In 197, 233 AT were targeted (196 intra-atrial reentrant tachycardia [64% cavotricuspid (mitral) isthmus-dependent, 33% systemic-venous incision-dependent] and 37 focal AT). In 93 noninducible patients, empirical substrate ablation was performed. Procedural success was achieved in 209 (84%) patients. AT recurred in 148 (54%) 10 (interquartile range, 0-25) months after RFCA. AT-free survival was significantly better in patients with no atrial repair/cannulation only and in patients with complete procedural success independently of CHD complexity. From 94 patients undergoing reablation, the initially targeted substrate had recovered in 64%. Conclusions: In contemporary patients with CHD, outcome after AT ablation is associated with presence of prior atrial surgery and achievement of predefined procedural endpoints rather than CHD complexity. Techniques to improve lesion durability are likely to further improve long-term outcome