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

Abstract

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 contrast, no significant relationship was observed between the ratio of right ventricular to left ventricular pressure and Lown grade or between right ventricular systolic pressure and Lown grade. Discriminant analysis revealed risk factors associated with postoperative ventricular arrhythmias are follow-up duration (partial F = 3.22, p < 0.01), right ventricular to pulmonary artery pressure gradient (partial F = 3.35, p < 0.01), and operative method (partial F = 2.4, p < 0.05). Despite antiarrhythmic therapy, 11 of 22 late postoperative deaths occurred suddenly, presumably from ventricular arrhythmias. In this series of patients, the right atrial and pulmonary artery approach significantly reduced the risk of life-threatening ventricular arrhythmias after repair of tetralogy of Fallot.