Prognostic Factors for Late Ventricular Arrhythmias after Repair of Tetralogy of Fallot

During a median follow-up period of 9 years (ranging from 9 months to 25 years), 24-hour ambulatory electrocardiographic studies were undertaken in 155 patients after repair of tetralogy of Fallot. The patients were divided into two groups. Group A consisted of 76 patients in whom the right ventricular approach was used and group B comprised 79 patients whose repair was through the right atrium. A transannular patch was employed in all patients in group A and in none of the patients in group B. Age at surgery was between 1 and 37 years (median age 4.8 years). During follow-up, 37 patients (48.6%) in group A had significant ventricular arrhythmias (Lown grade 2 or higher) and 13 patients (15.4%) in group B had significant ventricular arrhythmias. A close relationship was observed between age at surgery and Lown grade (R2 = 0.374, p < 0.001) and between follow-up duration and Lown grade (R2 = 0.514, p < 0.001), especially when the two groups were analyzed separately (R2 = 0.502, 0.476, p < 0.001). In contra...