Abstract 15416: Longitudinal Assessment of Electrical-Mechanical Interactions in Children and Young Adults With Repaired Tetralogy of Fallot

Abstract

Introduction: Electrical-mechanical interactions contribute to arrhythmias, sudden cardiac death, and right ventricular remodeling in repaired tetralogy of Fallot (TOF). Hypothesis: There are significant changes in electrocardiographic properties and electrical-mechanical interactions that occur over time after complete TOF repair and with pulmonary valve replacement (PVR). Methods: This retrospective cohort study of 177 patients, initially recruited for a cross-sectional research protocol, underwent complete TOF repair at 0.3±0.9 years with 21.5±4.2 years of clinical follow-up. We assessed ECG, Holter, cardiopulmonary exercise testing (CPET), and MRI data. We used linear mixed effects models to examine QRS duration (QRSd) and its rate of change over time, associations between comparable ECG and MRI, Holter and MRI, ECG and Holter, ECG and CPET, and pre-PVR and post-PVR results. Results: QRSd increased after TOF repair, but the rate of change decreased from 5.2 ms/year 1 year post-operatively to 1.7 ms/year 20 years post-operatively. Twenty years from TOF repair, post-operative arrhythmias included ventricular ectopy: ventricular tachycardia (4 of 20 patients) on Holter and premature ventricular contractions (14 of 19 patients) on CPET. QRSd was positively associated with right ventricular (RV) volumes, RV:left ventricular (LV) end-diastolic volume ratio, and complex ventricular ectopy on Holter; and negatively associated with RV ejection fraction (EF). The association between QRSd and RV volumes was weaker post-PVR. QRSd and its rate of change were associated with increased LV volume post-PVR. Complex ventricular ectopy was associated with lower LV EF, and significant atrial ectopy was associated with higher LV mass-to-volume ratio. Conclusions: Substantial ventricular ectopy occurs in adolescents and young adults after repair of TOF. Electrophysiologic changes included QRSd prolongation that progressively slowed. QRSd and its rate of change were associated with published risk factors for arrhythmia and sudden cardiac death, and with indications for PVR. Our ongoing research aims to identify an optimal threshold of pre-PVR QRSd and its rate of change that preserves bi-ventricular electrical-mechanical coupling post-PVR.