Congenital Heart Disease

1348718 - Septal Segmental Displacement is Related to Decreased Exercise Capacity in Repaired Tetralogy of Fallot Patients

Thursday, January 26, 2023

1:00 PM – 2:00 PM

Location: Pacific Jewel

Primary Author(s)

SK

Sarah Kollar, DO

Cardiology Fellow
Children's National Medical Center
Washington, United States

Co-Author(s)

HL

Heather V. Luquette, MSc

Program Manager of Exercise Physiology
Children's National Hospital
Washington, District of Columbia, United States
BK

Berthold Klas, BSc

Product Marketing Manager
Tomtec Imaging Systems
Corrales, New Mexico, United States
Olga H. Toro-Salazar, MD

Head of Non-Invasive Imaging and Cardio-Oncology
Connecticut Children's Medical Center
Glastonbury, Connecticut, United States

Presenting Author(s)

Yue-Hin Loke, MD

Assistant Professor of Pediatrics
Children's National Hospital, Maryland, United States

Disclosure(s):

Olga H. Toro-Salazar, MD: No financial relationships to disclose

Yue Loke: No financial relationships to disclose

Background: Repaired Tetralogy of Fallot (rTOF) patients experience right ventricular (RV) remodeling secondary to chronic pulmonary insufficiency (PI). The adaptive mechanisms of the RV in response to chronic PI have not been clarified. Atypical septal wall recruitment towards the RV, otherwise known as septal segmental displacement, can be seen in rTOF patients, Figure 1. Over time, the adaptive mechanisms in rTOF patients eventually fail and these patients experience decreased exercise capacity. Therefore, we investigated the relationship between septal segmental displacement, as part of RV remodeling in rTOF patients, and exercise capacity, as a marker of clinical decline and need for pulmonary valve replacement.

Methods: This was a retrospective study of 16 rTOF patients and 16 normal patients who underwent cardiac magnetic resonance (CMR). All rTOF patients additionally underwent cardiopulmonary exercise stress testing (CPET) within 12 months of the CMR study. Feature tracking of the RV wall was performed by conventional software (QStrain, Medis). The average magnitude of septal segmental displacement was calculated via custom algorithms, then indexed to RV size (RV-SSDi). Correlations of RV-SSDi were performed against conventional CMR parameters, strain, and CPET data.

Results: The mean RV end diastolic volume index (EDVi) was 141.2 ± 32.6 ml/m² and RV ejection fraction (EF) was 50.5 ± 5 %. The mean VO2 Max was 28.9 ± 6.9 ml/kg/min and percent predicted VO2 Max was 66.8 ± 17.7 %. rTOF patients demonstrated abnormal septal segmental displacement with a mean RV-SSDi of 0.68 ± 0.31, compared to -0.65 ± 0.56 in controls (p < 0.0001). RV-SSDi correlated with decreased magnitude left ventricular (LV) global circumferential strain (r = 0.540, p = 0.031), Figure 2 A. RV-SSDi also correlated with decreased percent predicted VO2 Max (r = -0.699, p = 0.003), Figure 2B. There was no correlation between VO2 Max and conventional CMR parameters, such as RV EDVi, RV end systolic volume index (ESVi), RV EF, LV ESVi, and LVEF, Table 1.

Conclusion:

Patients with rTOF have abnormal RV-SSDi, which is related to decreased LV function and exercise capacity. Conventional CMR parameters did not correlate with exercise capacity. Future longitudinal studies should assess RV-SSDi, which may be a useful parameter in determining optimal timing for pulmonary valve replacement prior to irreversible RV dysfunction.