To evaluate the use of the tissue tracking (TT) technique to measure myocardial strain left ventricular in post-Fontan children with preserved ejection fraction (pEF). Nineteen (male/female, 10/9) patients with univentricular hearts after completion of the Fontan circulation (post-Fontan group) and 19 age- and gender-matched healthy children (control group) were retrospectively enrolled. Cardiovascular magnetic resonance (CMR) imaging was conducted on a 1.5-T MRI scanner. Global and regional strains of the left ventricle in post-Fontan patients (EF > 55%) and controls were obtained using CMR-TT software. The Mann-Whitney U test was used to compare parameters between the two groups. Correlation between EF and strain was investigated using Pearson correlation coefficients. The Bland-Altman method was used to identify the inter- and intra-observer agreement in measurement of global strain. Global longitudinal strain was lower in post-Fontan patients than in healthy controls (- 18.87 ± 4.61 vs. -19.72 ± 1.58; P = 0.54), though the difference was not statistically significant. Global circumferential strain and global radial strain were significantly lower in post-Fontan patients than in healthy controls (- 14.55 ± 3.79 vs. -19.91 ± 1.97; P < 0.001; and 29.62 ± 8.41 vs. 36.85 ± 5.95; P = 0.01; respectively). The regional circumferential strain (RCS) decrease was marked in regional segments compare with post-Fontan patients and controls (basal, - 11.81 ± 2.98 vs. - 16.21 ± 2.72, P < 0.001; mid, - 15.05 ± 3.31 vs. - 20.17 ± 2.28, P = 0.005; apical, - 16.86 ± 3.09 vs. - 23.37 ± 2.62, P < 0.001). All circumferential and longitudinal parameters had an inter-observer ICC of ≥ 0.85, but this coefficient was lower for radial parameters. CMR-TT appears to be a feasible technique for identification of early myocardial dysfunction in post-Fontan with pEF.
Keywords: Cardiac magnetic resonance; Fontan; Pediatric; Strain.