Quantification of left ventricular performance in different phenotypes of hypertrophic cardiomyopathy

Objective To evaluate the characteristics of left ventricular structure, function, myocardial mechanics, hemodynamics and synchrony in different phenotypes of hypertrophic cardiomyopathy (HCM) using state-of-the-art echocardiography. Methods A consecutive series of 85 adult HCM patients who were admitted to the Xi Jing HCM center from January 2016 to November 2017 were collected. According to the peak left ventricular outflow tract pressure gradient in exercise stress echocardiography, the patients were divided into three groups: patients with non-obstructive HCM (n=28), those with labile-obstructive HCM (n=27), and those with obstructive HCM (n=30). In addition, 16 normal family members of HCM patients were included as control group. Two-dimensional speckle tracking imaging, tissue Doppler imaging and exercise stress echocardiography were used to evaluate the left ventricular function in resting and exercise states. Results ①As compared with the control group, left ventricular end-diastolic diameter decreased and left ventricular ejection fraction increased in all three HCM groups(all P 0.05). The obstructive HCM had the lowest mitral annular plane systolic excursion (MAPSE) and s′, and the longest systolic peaking time standard deviation(Ts-SD) and early diastolic peaking time standard deviation(Te-SD) (all P<0.05). The left ventricular diastolic function of obstructive HCM (e′, the E/e′ ratio and the left atrial volume index) was the worst, labile-obstruction and non-obstructive HCM were better, and the control group was the best (all P<0.001). ③During exercise, the GLS, GCS, GRS, twist of the left ventricle and the MAPSE were the lowest in the obstructive HCM, which increased in the labile-obstructive and non-obstructive HCM, and were best in the control group. The Ts-SD and Te-SD were the shortest in the control group, were prolonged in non-obstructive and labile-obstruction HCM, and were longest in obstructive HCM (all P<0.05). Additionally, the exercise time of the control group was the longest, followed by non-obstructive and labile-obstruction HCM, and the shortest in the obstructive HCM (all P<0.05). The METs of obstructive HCM were significantly lower than the other three groups (all P<0.05). Conclusions In obstructive HCM, the left ventricular systolic strain and synchronization, as well as the MAPSE, are significantly impaired in patients both at rest and during exercise. The patients with labile-obstructive and non-obstructive HCM have reduced left ventricular GLS, twist, and e′, but normal left ventricular GCS, GRS, synchrony, and MAPSE at rest, which are all impaired during exercise. Key words: Two-dimensional speckle tracking imaging; Tissue Doppler imaging; Hypertrophic cardiomyopathy; Exercise stress echocardiography; Myocardial mechanics; Synchrony