The change of left ventricular function and mechanical dispersion in patients with hypertrophic cardiomyopathy: a study with exercise stress echocardiography

Abstract

Objective To investigate the association between the change of left ventricular (LV) function and mechanical dispersion (MD) and exercise capacity in patients with hypertrophic cardiomyopathy (HCM) by exercise stress echocardiography. Methods Sixty-five HCM patients [40 cases of hypertrophic non-obstructive cardiomyopathy (HNCM), 25 cases of hypertrophic obstructive cardiomyopathy (HOCM)] and 25 control subjects were recruited.LV function, MD and exercise capacity were evaluated by two-dimensional speckle-tracking imaging and echocardiography at rest and during exercise, and the following parameters of LV function were recorded: LV global longitudinal strain (LVGLS), MD, early diastolic strain rate (SRe), the ratio of peak early diastolic mitral inflow and annulus velocity (E/e′), LV outflow tract gradient (LVOTG); LV functional reserve was assessed by ΔLVGLS and ΔSRe; exercise capacity was evaluated by metabolic equivalents (METs). The association between the change of LV function and MD and exercise capacity was investigated. Results ①Compared with normal controls, LVOTG, E/e′ and MD increased, and LVGLS, SRe, ΔLVGLS, ΔSRe and METs decreased in HNCM patients at rest and during exercise (all P<0.05). ②LVOTG, E/e′ and MD were further increased, LVLGS, SRe, ΔSRe and METs were further reduced in HOCM patients compared with HNCM patients (all P<0.05). ③LVGLS and MD measured at peak exercise were associated with METs(r=-0.68, P<0.001; r=-0.43, P<0.001). ④ROC curve analysis showed LVGLS had a better predictive value for exercise intolerance in HCM patients, followed by E/e′ and MD. Conclusions LV function and mechanic reserve are reduced but MD is increased in HCM patients, especially in HOCM patients. Exercise capacity is associated with LV function and MD, which can predict the reduced exercise capacity in HCM patients. Key words: Exercise stress echocardiography; Two-dimensional speckle-tracking imaging; Cardiomyopathy, hypertrophic; Ventricular function, left; Mechanical dispersion