Abstract 14967: Rate of Growth of the Right Ventricular Outflow Tract in Repaired Tetralogy of Fallot: A Cardiovascular Magnetic Resonance Imaging Study

Abstract

Introduction: Patients with repaired tetralogy of Fallot (rTOF) often require pulmonary valve replacement (PVR). Transcatheter PVR is a less invasive alternative to surgery but many right ventricular outflow tracts (RVOTs) are too large. Understanding the rate of RVOT growth may help optimize timing of referral. This study examined the growth of the RVOT over time in rTOF. Methods: We retrospectively analyzed serial cardiac MRI (CMR) data from 121 patients with TOF (median 3 MRIs per patient; range 2 to 10) to calculate the rate of increase in perimeter-derived diameters of the proximal infundibulum, middle RVOT, and distal RVOT at the point of PA bifurcation (Figure 1). The median age at first CMR was 14.7 years (range 3.3, 43.6 years) with a mean interval between first and last CMR of 8 years ± 3 years. Results: All parameters increased over time. The proximal RVOT increased at a rate of 4.1 mm per 10 years (p < 0.001); the mid and distal RVOT both increased at a rate of 3.1 mm per 10 years (p < 0.001) (Figure 2). The RVOT was larger on average in patients with a higher RV end diastolic volume (RVEDV) at first MRI and in patients with a higher pulmonary regurgitation (PR) fraction at first MRI. Patients with greater increases in RV EDV (Spearman correlation 0.48, p < 0.001) or PR fraction (Spearman correlation 0.27, p = 0.003) over time had greater RVOT growth. Conclusions: This largest-to-date serial CMR study of patients with rTOF detailed the rate of growth of the RVOT over time. More rapid growth was associated with higher PR fraction and larger RVEDV. This data may be useful in the design and clinical use of transcatheter pulmonary valves.