Radiofrequency catheter ablation of ventricular tachycardia in patients post surgical repair of tetralogy of Fallot

Abstract

Objective: To investigate the clinical and electrophysiological features of ventricular tachycardia (VT) in tetralogy of Fallot (TOF) patients post surgical repair (rTOF) and to analyze the therapeutic effect and prognosis of radiofrequency ablation of rTOF-VT. Methods: This is a retrospective study. Consecutive patients with rTOF-VT, who were treated in Fuwai Hospital from January 2015 to March 2020, were enrolled. All the patients underwent right ventricular voltage mapping following routine cardiac electrophysiological examination, followed by linear or homogenizing radiofrequency ablation based on the low-voltage substrate. The clinical features, 3-dimentional electrophysiological substrate mapping, radiofrequency ablation and long-term prognosis of the enrolled patients were analyzed. Acute ablation success was defined as completion of linear or homogenizing ablation or intraoperative evoked VT as destination of the procedure. Patients were followed up at 3 and 6 months post operation and every year thereafter. The endpoints were sudden cardiac death (SCD) and recurrence of ventricular tachycardia. Results: A total of 20 patients with rTOF-VT were enrolled including 14 males with an age of (35.8±11.8) years. The electrocardiogram identified 23 types of ventricular tachycardia, 19 of which were originated from right ventricular inflow tract outlet. The most common clinical manifestations were heart murmur (19 cases, 95%) and syncope (4 cases, 25%). Electroanatomical substrate mapping was performed in 20 patients and evidenced localized or diffuse scar or low-voltage area of right ventricle. Intraoperative electrophysiological tests provoked ventricular tachycardia in 6 patients (30%), including 5 patients with hemodynamics disturbance. The acute success rate of radiofrequency ablation was 95% (19/20). The follow-up time was (31.1±17.7) months and the recurrence rate of ventricular tachycardia was 30% during follow-up period and 5 cases received repeat radiofrequency ablation and there was no recurrent ventricular tachycardia during follow-up post repeat radiofrequency ablation. Conclusions: The voltage substrate mapping under sinus rhythm is a feasible mapping method for rTOF-VT. Linear or flaky radiofrequency ablation of the slow conduction zone is safe and effective treatment strategy, the recurrence rate after the first radiofrequency ablation is still high, and the effectiveness of repeat radiofrequency ablation is satisfactory in this patient cohort.