Objectives: To assess the magnitude of myocardial displacement abnormalities and their alterations with the fibrosis, left-ventricular (LV) outflow tract obstruction (LVOTO) and hypertrophy in juveniles with hypertrophic cardiomyopathy (HCM).
Study design: Fifty-five children [age 12,5±4.6years, 38 (69,1%) males, 19 (34,5%) with LVOTO] with HCM and 20 controls underwent cardiovascular magnetic resonance. The LV feature tracking (FT) derived strain and strain rates were quantified. Results of FT analysis were compared between HCM subjects and controls and between children with and without LVOTO.
Results: Children with HCM exhibited decreased strain in both hypertrophied and nonhypertrophied segments versus controls. LV global longitudinal strain (LVGLS) rate (-0.69±0.04 vs -0.91±0.05, p=0,04), LV circumferential strain (LVCR) rate (-0.98±0.09 vs -1.27±0.06, p=0,02), LV radial strain (LVR) (18,5±1.9 vs 27,4±1.4, p<0,01) and LVR rate (0,98±0.1 vs 1,53±0.08, p<0,01) were substantially compromised in subjects with LVOTO vs without. In multivariable regression all LV myocardial dynamics markers, except for LVCR, exhibited a significant association with the degree of LVOTO. LVCR rate (β=0,31, p=0,02) and LVR (β=-0.24, p=0,04) were related to LV mass and only LVCR rate (β=0,15, p=0,03) was associated with the amount of LV fibrosis.
Conclusions: The reduction of all indices of LV myocardial mechanics in juvenile HCM patients was global but particularly pronounced in hypertrophied segments of the LV. The majority of the LV strains and strain rates were substantially compromised in subjects with LVOTO compared to patients without the obstruction. Myocardial mechanics indices seemed to be related to the degree of LVOTO rather than either to mass or the amount of fibrosis.
Keywords: Hypertrophic cardiomyopathy; Left-ventricular outflow tract obstruction; Strain.
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