Long-term outcome of twin atrioventricular node and supraventricular tachycardia in patients with right isomerism of the atrial appendage

BackgroundTwin AV nodes and resulting supraventricular tachycardia (SVT) have been described in right atrial isomerism (RAI).ObjectiveWe sought to analyze the long-term outcome of patients with RAI with a focus on rhythm disturbances.MethodsRetrospective study of 257 patients (152 male and 105 female, 1,171 patient-years) with RAI diagnosed between 1980 and 2005.ResultsSVT in 68 patients (26%) occurred at various ages from the prenatal period to 15 years and was only significantly associated with balanced ventricles (P = .009). Cardioversion was achieved in by verapamil in 6 of 6 cases (100%), adenosine in 18 of 21 cases (88%) and propranolol in 10 of 12 cases (83%). Electrocardiographic evidence of twin AV nodes, as shown by 2 discrete non–pre-excited QRS complexes, was found in 28 of 44 (64%) patients with more than 2 electrocardiograms, and was more frequent in those with balanced ventricles rather than a dominant ventricle and would increase risk of SVT. Recurrence of SVT was documented in 27 (40%) patients 1 day to 4.5 years after the first episode. However, the occurrence or recurrence of SVT was not associated with increased all-cause or surgical mortality or sudden death. Successful catheter ablation of ventriculoatrial pathways with junctional ectopic tachycardia at radiofrequency energy delivery was obtained in 5 of 6 patients.ConclusionThis study showed that twin AV nodes in RAI patients could be disclosed by serial electrocardiograms and that SVT, most likely a twin node tachycardia, was common and tended to recur but could be managed by ablation or medication.