1. Contribution of Endocardial Myocardial Deformation to the Preservation of Contractile Function in Hypertrophic Cardiomyopathy
Zi Wang1, Jianrong Xu2, Xuan Su1, Jun Pu1, Lingcong Kong1, Lianming Wu2, Meng Jiang*1, Ben He*1
1Department of Cardiology, Renji Hospital, School of Medicine Shanghai Jiaotong University, Shanghai, China
2Department of Radiology, Renji Hospital, School of Medicine Shanghai Jiaotong University, Shanghai, China
Background:
Unlike hypertensive heart disease (HHD), hyperdynamic contraction in the early stage of hypertrophic cardiomyopathy (HCM) is clinically noticeable. Understanding the cardiac deformation pattern behind this phenomenon is key to understanding the mechanism of maintaining contractile function in cardiac tissue..
Methods:
Standard cine images from cardiac magnetic resonance (CMR) in the short-axis and three long-axis views were recorded. Peak circumferential and longitudinal left ventricular strain was analysed. The myocardial deformation pattern was explored using two different strain tracking methods: myocardial voxel motion tracking and border tracking..
Results:
One hundred seventy-three participants were recruited, including 40 healthy controls, 40 patients with HHD (who served as positive controls) and 93 patients with HCM. Left ventricular ejection fraction (LVEF) in HCM patients (76±10%) displayed hyperdynamic contraction compared to that of HHD patients (65±12%) and healthy controls (70±9%) (P<0.001), whereas similar left ventricular mass and left ventricular mass indexes were observed between HCM and HHD patients. Regarding the circumferential strain, however, the deformation trend differed between HHD and HCM patients mainly in the endocardium, which presented with increased myocardial deformation in HCM patients, whereas no such movement diversity was observed from the subendo- or subepicardium. In addition, linear regression analyses showed a moderate correlation between global circumferential strain with LVEF; moreover, the inner layers (endocardium and subendocardium) had a stronger correlation with LVEF than the outer layers (epicardium and subepicardium) (r= for subendocardium vs for subepicardium; for endocardium vs for epicardium). Of note, a dramatic increase in endocardial circumferential strain was observed in HCM patients when the LVEF was below normal (-35.08±8.35%, P=0.046).
Conclusion:
Strain distinction in the circumferential but not longitudinal direction was found between HCM and HHD patients. The increase in endocardial circumferential strain may underlie the maintenance of hyperdynamic motion in HCM.
Presented at the 3rd SCMR China Symposium, in Shanghai, China, August 4-7, 2017