Zhongguo quanke yixue (Aug 2024)
Real-time Three-dimensional Echocardiography for Assessing Left Atrial Structural and Functional Changes in Mutation Carriers of Hypertrophic Cardiomyopathy
Abstract
Background Hypertrophic cardiomyopathy (HCM) is a common primary cardiomyopathy that is closely associated with sudden death in adolescents and athletes. The disease progression of HCM is prone to structural and functional alterations in the left atrium, leading to increased incidence of acute cerebrovascular accidents, embolism and atrial fibrillation, and a severe influence on the quality of life. Objective To evaluate the structural and functional changes in the left atrium of family members of familial hypertrophic cardiomyopathy (FHCM) with a positive genotype but negative phenotype by real-time three-dimensional echocardiography (RT-3DE), providing valuable references for early identification, assessment and management of family members of FHCM. Methods A total of 141 HCM patients and family members admitted in the General Hospital of Ningxia Medical University from October 2021 to August 2022 were recruited. Blood samples were collected for genetic testing. Subjects were divided into G+P+ group with positive genotype and positive phenotype of ventricular wall thickening (n=54), G+P- group with positive genotype and negative phenotype (n=35) and G-P- group with negative genotype and negative phenotype (n=31). Baseline characteristics of subjects were collected. Two-dimensional transthoracic echocardiography (2DE-TTE) scans of the left atrium and ventricle and RT-3DE scans of the left atrium, and their relevant parameters were collected as well. Pearson correlation analysis was performed to identify the correlation between RT-3DE parameters of the left atrium and 2DE-TTE parameters of the left ventricle in subjects of G+P- group. Results Genetic testing identified 24 subjects carrying the titin (TTN) gene, 2 carrying both the TTN and tropomyosin 1 (TPM1) gene, 6 carrying the myosin binding protein C3 (MYBPC3) gene, 2 carrying the troponin I3 (TNNI3) gene, 9 carrying the myosin heavy chain 7 (MYH7) gene, 8 carrying both the MYBPC3 and TNNI3 genes, and 3 carrying both the TTN and MYH7 genes in G+P+ group. In G+P- group, 11 subjects carrying the TTN gene, 8 carrying the MYBPC3 gene, 3 carrying the TNNI3 gene, 8 carrying the MYH7 gene and 5 carrying both the MYBPC3 and TNNI3 genes. 2DE-TTE parameters were analyzed. Subjects in G+P+ group showed significantly higher left atrial diameter index (LADI), left atrial volume index (LAVI), end-diastolic interventricular septal thickness (IVST), end-diastolic left ventricular posterior wall thickness (LVPWT), left ventricular mass (LVM), left ventricular mass index (LVMI) and ratio of early diastolic flow velocity peak to annular velocities (E/e') compared with those of G-P- group and G+P- group, but significantly lower end-diastolic volume index (EDVI) and end-systolic volume index (ESVI) (P<0.05). The peak velocity blood flow from left ventricular relaxation in early diastole (the E wave) and late diastole caused by atrial contraction (the A wave) were significantly higher in subjects of G+P+ group than those of G-P- group (P<0.05). The A wave and E/e' were significantly higher in subjects of G+P- group than those of G-P- group (P<0.05). RT-3DE parameters of the left atrium were analyzed. Subjects in G+P+ group had significantly higher maximum (LAVImax) and minimum left atrial volume indices (LAVImin), and pre-contraction volume index (LAVIpre), but significantly lower left atrial total (LATEF), passive (LAPEF) and active ejection fractions (LAAEF) compared to those of G-P- group and G+P- group (P<0.05). LATEF and LAAEF were significantly lower in G+P- group than in G-P- group (P<0.05). Pearson correlation analysis showed positive correlations of LAVImax and LAVIpre with IVST (r=0.385 and 0.399, respectively; both P<0.05), positive correlations of LAVImax and LAVImin with LVM (r=0.371 and 0.432, respectively; both P<0.05), and negative correlations of LATEF and LAAEF with LVM (r=-0.375 and -0.401, respectively; both P<0.05) in G+P- group. Conclusion RT-3DE can reflect changes in left atrial function in family members of FHCM with positive genotype and negative phenotype by measuring atrial volumes, and they may already suffer from the left atrial dysfunction even when the atrial size is normal. Changes in their left atrial volume are positively correlated with changes in left ventricular wall thickness and mass, while functional changes are negatively correlated with the LVM.
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