Correlation of advanced echocardiography, cardiac MRI and functional capacity in patients with repaired Tetralogy of Fallot

BACKGROUND Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease (CHD), encompassing 6% of all CHDs, and it represents the most common CHD with long-term survivors. Therefore, patients with repaired TOF (rTOF) require serial imaging monitoring due to potential complications, particularly pulmonary insufficiency. Over the last few decades, new imaging modalities such as three-dimensional echocardiography (3DE) and speckle-tracking echocardiography (STE) have emerged as valuable tools for follow-up and interventional indications in this population. This single-center retrospective study aims to provide a comprehensive evaluation of their potential role in managing patients with rTOF. METHODS AND MATERIALS This is a retrospective, single-center study that enrolled patients with rTOF who were followed from 2022 to 2026 at the University of Padua’s Pediatric Cardiology Unit. Patients were included if they were under continuous follow-up at our Center and had both a full transthoracic echocardiography (TTE) assessment and a cardiopulmonary exercise test (CPET) evaluation available. Echocardiographic assessment included both 3DE and two-dimensional echocardiography (2DE) to obtain a comprehensive standard and advanced echocardiographic evaluation, including STE. Collected data also included cardiovascular magnetic resonance (CMR) measurements and functional parameters derived from cardiopulmonary exercise tests (CPETs). These evaluations were obtained post-procedure for patients who underwent pulmonary valve replacement (PVR). Patients were divided into two groups according to CPET performance. Normal exercise capacity was defined as VO2 peak ≥ 50%. RESULTS 30 patients met the inclusion criteria and were enrolled in this study. Correlations between CMR, 3DE, and STE measurements with CPET parameters were the main goal of this study. No statistically significant results were obtained. Comparisons of the aforementioned measurements between patients with normal and impaired functional capacity were also evaluated. 2D left ventricular end-diastolic volume index (LVEDVi), S’ wave, and 3D right ventricular stroke volume (RVSV) showed a statistically significant difference between patients with normal and impaired exercise capacity. A reduction in right atrial (RAS) parameters was observed in patients with impaired exercise capacity, but the statistical significance threshold was not met. Patients with normal exercise capacity showed significantly higher CMR-derived right ventricular end-diastolic volume (RVEDV) and right ventricular end-systolic volume (RVESV). CONCLUSIONS This study provides a comprehensive multimodality imaging assessment in a small cohort of patients with rTOF. In light of the evidence from the literature, although no statistically significant correlations were found in this study, further analyses with larger cohorts are advisable to better assess the relationship between 3DE, STE, and functional capacity, as well as the complexity of interventricular interaction in the rTOF population.