Assessment of left ventricular myocardial work in chronic heart failure patients by pressure-strain loop

Objective To explore the application value of pressure-strain loop (PSL) in evaluating left ventricular myocardial work (MW) in patients with chronic heart failure (CHF). Methods Seventy patients with CHF were selected as case group(CHF group) and were divided into 2 groups according to the left ventricular ejection fraction (LVEF) in ultrasonic cardiogram: LVEF preserve group (HFpEF group, LVEF≥50%, n=35) and LVEF reduced group (HFrEF group, LVEF<50%, n=35). Thirty-three healthy volunteers were selected as control group at the same period. Two-dimensional dynamic images in apical two chamber, three chamber and four chamber views were collected by two-dimensional speckle-tracking. Using the off-line EchoPAC software, a tracing analysis was conducted and the blood pressure was entered to obtain left ventricular global longitudinal strain (GLS), global MW index (GWI), global constructive work (GCW), global wasted work (GWW) and MW efficiency (GWE). The differences of GLS and MW parameters (GWI, GCW, GWW, GWE) were compared between each groups, and Pearson correlation was used to analyze the correlation between MW parameters and LVEF. Results Compared with the control group and HFpEF group, the left atrial dimension(LAD), left ventricular end-diastolic dimension(LVDd), left ventricular end-diastolic volume(LVEDV), left ventricular end-systolic volume(LVESV) in HFrEF group increased, while LVEF decreased significantly(P<0.05). Compared with the control group, LAD in HFpEF group increased, the vaules of GLS, GWI, GCW were obviously lower in HFpEF group and HFrEF group(all P<0.05), GWW was higher and GWE was lower in HFrEF group(all P<0.05). GLS, GWI, GCW, GWE decreased and GWW increased in HFrEF group than those in HFpEF group, and all the differences were statistically significant(all P<0.05). In CHF group, GWW was negatively correlated with LVEF (r=-0.521, P<0.001) while positive correlations between GWI, GCW, GWE and LVEF were discovered (r=0.846, 0.807, 0.788; all P<0.001). Conclusions PSL can effectively evaluate the left ventricular MW in CHF patients. It has a certain correlation with LVEF and can reflect left ventricular systolic function. It provides a new reference index for the clinical diagnosis and evaluation of prognosis in CHF patients. Key words: Echocardiography; Heart failure; Pressure-strain loop; Ventricle, left; Myocardial work