CONGENITAL HEART DISEASE Ventricular Arrhythmias in Postoperative Tetralogy of Fallot

Ventricular arrhythmias in patients after total surgical repair of tetralogy of Fallot have been associated with late sudden death. In this large multicenter retrospective study of 359 patients with postoperative tetralogy of Fallot, spontaneous ventricular premature complexes (VPCs) on 24. hour ambulatory electrocardiographic monitoring and laboratory-induced ventricular tachycardia (VT) by electrophysiologic stimulation were analyxed. The mean age at surgical repair was 5 years and the mean follow-up duration after repair was 7 years. Spontaneous VPCs on ambulatory monitoring were found in 46% and imluced VT on electrophysiologic stimulation was found in 17% of patients. Both spontaneous VPCs and induced VT were signifkantly related to delayed age at repair, longer follow-up interval, symptoms of syncope or presyncope and right ventricular systoiic hypertension (>60 mm Hg) (p 8 mm Hg. The VPCs on ambulakwy monitoring were more complex with increasing age at repair and follow-up duration. Induction of VT on electrophysidogic stimulation correlated with spontaneous VPCs including VT on 24-hour ambulatory electrocardiographii monitoring. The electrophysiologic stimulation protocol varied and the imluction of VT increased with a more aggressive stimulation protocol. While induced sustained monomorphic VT was related to all forms of spontaneous VPCs, induced nonsustained polymorphic VT was related to more complex forms of VPCs on ambulatory monitoring. VT was not induced in asymptomatic patients who had normal 24-hour ambulatory electrocardiographic monitoring and normal right ventricular systolic pressure. Late sudden death occurred in 5 patients, most of whom had spontaneous VPCs on ambulatory monitoring and right ventricular diistolii pressure >8 mm Hg, but none had induced VT with a nonaggressive electrophysiologic protocol. (Am J Cardiol1990;65:655-661) S urgical repair of tetralogy of Fallot results in improved duration and quality of life. The lo-year survival rate is >90%.1.2 However, sudden death is a well-recognized late event with a reported incidence as high as 4.6%.‘-4 Late sudden death is attributed to various cardiac arrhythmias including progressive conduction disturbance with late complete heart block,3,5.6 sinus node dysfunction7 and ventricular premature complexes (VPCS).~-‘~ These reports focus on VPCs as the primary etiology of late sudden death. Older age at surgical repair, longer interval after repair and poor right ventricular hemodynamic status are considered additional risk factors for late sudden death.16-l8 Induction of ventricular tachycardia (VT) by electrophysiologic stimulation has been associated with spontaneous VPCs in children with postoperative tetralogy of Fallot.4J5J6J9 This large multicenter retrospective study in patients with postoperative tetralogy of Fallot had 2 purposes: to analyze and relate spontaneous VPCs to laboratory-induced VT on electrophysiologic stimulation, and to investigate the prognostic significance of these factors to sudden death.