Aly S; Mertens L; Friedberg MK; Dragulescu A;

Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography [J Am Soc Echocardiogr] 2023 May 24.
Date of Electronic Publication: 2023 May 24.

Background: Ventricular dysfunction is a significant clinical challenge in the long-term follow-up of patients with single ventricle (SV) physiology. Ventricular function and myocardial mechanics can be studied using speckle-tracking echocardiography (STE) which provides information on myocardial deformation. Limited information is available on serial changes in SV myocardial mechanics after the Fontan operation.
Aims: In this study, we wanted to describe serial changes in myocardial mechanics in children after the Fontan operation and the relationship of these changes with myocardial fibrosis markers as obtained by cardiac magnetic resonance (CMR) and exercise performance parameters.
Hypothesis: We hypothesized that ventricular mechanics declines in SV patients over time and is associated with increased myocardial fibrosis and reduced exercise performance.
Methods: Single-center retrospective cohort study including adolescents after the Fontan operation. Ventricular strain and torsion were assessed using STE. CMR and cardiopulmonary exercise testing data closest to the latest echocardiograms were obtained. The most recent follow-up echocardiographic and CMR data were compared to sex and age-matched controls as well as to individual patients’ early post-Fontan data.
Results: 50 SV patients (31 LV, 13 RV, and 6 co-dominant) were included. Median time at follow-up echocardiogram from the time of Fontan was 12.8 (10.6-16.6) years. Compared to early post-Fontan echocardiograms, follow-up assessment showed reduced global longitudinal strain [-17.5% (-14.5 to -19.5) vs -19.8% (-16.0 to -21.7), p=0.01], circumferential strain [-15.7% (-11.4 to -18.7) vs -18.9% (-15.2 to -25.0), p=0.009], reduced torsion [1.28˚/cm (0.51 to 1.74) vs 1.72˚/cm (0.92 to 2.34), p= 0.02] with decreased apical rotation but no significant change in basal rotation. Single RVs had lower torsion compared to single LVs [1.04 ˚/cm (0.12 to 2.20) vs 1.25 ˚/cm (0.25 to 2.51), p=0.01]. T1 values were higher in SV compared to controls [1009±36ms vs 958±40ms, p=0.004], and in single RV compared to LV (1023±19ms vs 1006±17ms, p=0.02). T1 correlated circumferential strain (r=0.59, p=0.04) and inversely correlated with O ₂ saturation (r=-0.67, p<0.001), and torsion (r=-0.71, p=0.02). Peak oxygen consumption correlated with torsion (r=0.52, p=0.001) and untwist rates (r=0.23, p=0.03) CONCLUSION: Post Fontan, there is a progressive decrease in myocardial deformation parameters. The progressive decrease in SV torsion is related to a decrease in apical rotation, which is more pronounced in single RVs. Decreased torsion is associated with increased markers of myocardial fibrosis and lower maximal exercise capacity. Torsional mechanics may be an important parameter to monitor after Fontan palliation but further prognostic information is required.