Comprehensive rhythm evaluation in a large contemporary Fontan population

OBJECTIVES: Rhythm disturbances are an important cause of morbidity in Fontan patients. Currently, the total cavopulmonary connection is performed by using the intra-atrial lateral tunnel (ILT) ('baffle ILT' or 'prosthetic ILT'), or the extracardiac conduit (ECC). The aim of the study was to evaluate rhythm abnormalities and compare the surgical techniques in a contemporary cohort. METHODS: In a cross-sectional multicentre study, 115 patients (age 12.5 +/- 3.1 years) underwent rhythm evaluation using ECG, exercise testing and Holter, including heart rate variability. Medical history was reviewed for episodes of arrhythmia. RESULTS: Sinus node dysfunction (SND) was found in 29%, 3 of whom required pacemaker therapy. No difference was found in the incidence of SND between ILT and ECC patients. Sinus pauses occurred only in the ILT group. Exercise testing showed no difference in peak heart rate between the groups. Heart rate reserve (P = 0.023) and heart rate recovery (HRrecovery) (P < 0.001) were lower in ILT patients. Atrial arrhythmias were more common in ILT patients (15 vs 1%, P = 0.004), but only in those with a baffle ILT. One patient had symptomatic ventricular tachycardia (VT). Holter recordings showed sub-clinical VT in 6% of patients, which was associated with larger end-diastolic (P = 0.035) and end-systolic volumes (P = 0.029). CONCLUSIONS: The overall incidence of arrhythmia was low, although SND was frequently present in both Fontan groups. ILT patients had slower HRrecovery, and ILT patients with the more extensive baffle technique had more atrial arrhythmias and more sinus pauses. The significance of asymptomatic ventricular arrhythmias in this young population remains to be determined.