Myocardial Deformation Analysis In Hypertrophic Cardiomyopathy With Sarcomere Mutations: Insights From 2,221 Patients Within The Nhlbi-Hcm Registry

Introduction: Hypertrophic cardiomyopathy (HCM) is caused by mutations in sarcomere genes that alter myocardial contractility and relaxation. Three-dimensional myocardial deformation analysis (3D-MDA) may elucidate left ventricular (LV) abnormalities associated with sarcomere genotype status. Hypothesis: We hypothesize that HCM patients with sarcomere mutations have changes in myocardial contractility profiles that are associated with adverse LV architectural changes. Methods: 3D-MDA was measured using validated feature-tracking software applied to 2D cine cardiac MRI studies in 2,221 genotyped patients within the NHLBI HCM Registry. Results: Baseline, cardiac MRI, and 3D MDA-derived strain characteristics stratified by sarcomere status are shown in Table 1. Sarcomere positive patients were younger, had less LV outflow tract obstruction and lower indexed LV mass, but similar LVEF and trend towards higher serum NT-proBNP levels. Maximal wall thickness, measures of diffuse myocardial fibrosis (native T1, extracellular volume fraction) were elevated with corresponding reduction in global radial strain. Global minimum principal and epicardial layer conventional strain values were higher in sarcomere positive patients. Epicardial minimum principal strain was highly correlated with indexed LV mass (r=0.42, P<0.0001), maximal wall thickness (r=0.29, P<0.0001), LVEF (r=-0.33, P<0.0001), late gadolinium enhancement (r=0.22, P<0.0001) and NT-proBNP (r=0.21, P<0.0001) levels in those with sarcomere mutations. Conclusions: Sarcomere positive HCM patients had differences in myocardial deformation strain profiles that were correlated to LV architectural changes and NT-proBNP levels despite lower indexed LV mass. More sensitive measures of contractile dysfunction may help elucidate pathophysiological mechanisms by which sarcomere mutations cause disease progression and adverse clinical outcomes in HCM.