Abstract
ObjectivesTo investigate biatrial mechanics and their relation with left ventricular outflow tract (LVOT) obstruction (LVOTO), the degree of hypertrophy, indices of ventricular diastolic function and fibrosis in children with hypertrophic cardiomyopathy (HCM).MethodsFifty-five consecutive, prospectively recruited children with HCM (mean age 12.5 ± 4.6 years, 69.1% male), 19 (34.5%) of whom had LVOTO, underwent cardiac magnetic resonance and echocardiography with quantification of phasic components of biatrial function, biventricular diastolic function and fibrosis. Twenty healthy, sex-matched subjects served as controls.ResultsWe found a significant increase of left atrial (LA) and right atrial (RA) volumes and reduction in the majority of indices of contractile function, strains and strain rates (p < 0.05) in children with HCM compared with controls. Nearly all of the LA dynamics markers attained a significant association with the LVOT gradient (p < 0.05), the RA volumes and contractile functions were affected by LV fibrosis and mass (p < 0.05), and the RA mechanical components were related to the degree of LVOTO (p < 0.05). The minority of biatrial dynamics markers were associated with indices of ventricular diastolic function.ConclusionsThe majority of biatrial volumetric and functional indices were severely compromised in children with HCM compared with controls. The degree of LVOTO appears to trigger LA volumetric and LA and RA mechanical malfunction. On the other hand, the deterioration of RA volumetric components was linked to LV fibrosis and mass.Key Points• Biatrial function was severely compromised in children with HCM.• Left atrial malfunction was associated with the degree of LVOTO.• Fibrosis and LV mass were related to RA volumetric and contractile dysfunction.• The degree of LVOTO was linked to right atrial mechanical abnormalities.
Highlights
Hypertrophic cardiomyopathy (HCM) is a primary, genetically triggered myocardial disease characterised by uncontrolled left ventricular (LV) muscle proliferation, diverse clinical presentation and significant outcomes [1, 2]
Fibrosis and LV mass were related to right atrium (RA) volumetric and contractile dysfunction
Criteria for inclusion in the study included an age younger than 18 years at the time of diagnosis and echocardiographic evidence of LV hypertrophy defined as a diastolic septal thickness or LV diastolic wall thickness z-score greater than 2 [determined as more than two standard deviations from the mean value for the population corrected for body surface area (BSA)] in the absence of haemodynamic conditions that could account for the observed hypertrophy [2]
Summary
Hypertrophic cardiomyopathy (HCM) is a primary, genetically triggered myocardial disease characterised by uncontrolled left ventricular (LV) muscle proliferation, diverse clinical presentation and significant outcomes [1, 2]. Its complex pathomorphology includes fibre disarray, microvasculature abnormalities and vast fibrosis [3] All these serve to decrease LV compliance and result in abnormal LV relaxation and a restrictive filling pattern [4]. Kowallick et al demonstrated the feasibility of applying CMR FT for analysing biatrial mechanics in healthy subjects [14]. They reported that fibrosis played a larger role than hypertrophy in the development of LA dysfunction in adults with HCM [15]. Despite this progress, contemporary knowledge of LA and especially RA dynamics in a juvenile population with HCM remains rudimentary. This study focuses on investigating biatrial performance and its relation to LV outlet tract obstruction (LVOTO), biventricular diastolic function and fibrosis in children with HCM
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