Ablation of atrial tachycardias with radiofrequency current after surgical repair of complex congenital heart defects.

Introduction: Atrial tachycardias are a common problem following the surgical repair of complex congenital heart defects (CHD) and have a poor response to medication. The aim of this study was to describe the results of the treatment of such tachycardias with radiofrequency ablation in our hospital.

Methods: A retrospective study was performed of the medical records and electronically stored data from electrophysiological studies (EPS) and ablation procedures in patients with atrial tachycardias following the surgical repair of CHD. Established electrophysiological techniques were used in all patients, while newer three-dimensional imaging methods were also employed in some cases. Ablation was carried out using a radiofrequency generator and catheters with a 4-10 mm terminal electrode.

Results: Twenty-two patients aged 11-45 years (30.6 +/- 10.8), including 9 women, underwent an EPS and ablation of atrial tachycardias after the surgical repair of CHD. All had recurrent tachycardias refractory to antiarrhythmic medication. The anatomical diagnoses were tetralogy of Fallot (8), transposition of the great arteries (6), single ventricle (3), and other (5). Most patients had typical atrial flutter and/or incisional atrial reentrant tachycardia. The initial success rate of ablation for all arrhythmias was 88% in patients with tetralogy of Fallot, 83% for transposition of the great arteries, 66% for single ventricle, and 80% for the other diagnoses. Three-dimensional imaging was of significant assistance in mapping and ablation and in reducing the duration of fluoroscopy. Two vascular complications (femoral arteriovenous fistulae) were observed. The tachycardia recurrence rate was 54%. After repeated procedures, 59% of patients were free of arrhythmias and antiarrhythmic medications. No patient with a single ventricle remained free of arrhythmias during follow up, while in the other groups the arrhythmia/drug-free rate was 66-75%. Two patients with unsuccessful ablation died, one from heart failure and the other because of the tachycardia.

Conclusions: Atrial tachycardias in patients with surgically treated CHD are associated with increased morbidity and mortality. Radiofrequency ablation has satisfactory results. In spite of the high relapse rate, a significant number of patients can become free of arrhythmias after repeat procedures.