Application of the Left Ventricular Pressure-Strain Loop Technique in Monitoring Improvement Factors of Patients With Heart Failure Reduced Ejection Fraction

Abstract

The left ventricular pressure-strain loop (PSL) is a new technique based on ultrasound for noninvasive quantitative evaluation of global and local myocardial work (MW). This study is aimed at evaluating improvement factors of patients with heart failure (HF) reduced ejection fraction (HFrEF) using the PSL technique. A total of 88 patients with HF were enrolled in this study, which had ≤ 40% left ventricular ejection fraction (LVEF). The EchoPAC workstation was used to obtain the global longitudinal strain (GLS) and MW parameters of the left ventricle. All patients have taken medicines for HF treatments for 6-12 months. The improvements of HF after therapies were evaluated according to the following recommended criteria. The clinical characteristics of patients with improved and nonimproved groups were stratified via univariate or multivariate logistic regression analysis, receiver operating characteristic (ROC), and the area under ROC (area under the curve (AUC)). There were no significant differences in general medical information, the underlying diseases, laboratory findings, myocardial enzyme activities, and taking medicines between the improved and nonimproved LVEF patients (p > 0.05). There were significant differences in LVEF of patients at admission, left ventricular end-diastolic diameter (LVEDD), interventricular septum thickness (IVST), early diastolic mitral flow peak velocity E (E peak), GLS, global myocardial work index (GWI), global myocardial constructive work (GCW), and global myocardial work efficiency (GWE) between the two groups (p < 0.05). Univariate and multivariate logistic regression analyses confirmed that GWI and GCW were critical predictive factors for LVEF improvement in patients with HF. ROC curve showed that the AUC of GWI and GCW were 0.796 and 0.779 at the cut-off of 741 mmHg% for GWI and 973.5 mmHg% for GCW, respectively. The sensitivities of GWI and GCW were 65% and 75%, and the specificities of GWI and GCW were 83.3% and 79.2% at given cut-off values. These results revealed that GWI and GCW were independent predictors of improvement of LVEF in patients with HFrEF.

Keywords: echocardiography; heart failure; left ventricular ejection fraction; myocardial work; pressure–strain loop.

Figure 1

PSL technique shows the left ventricle myocardial work. This image reveals the left ventricle myocardial work parameters by echocardiography. (a) PSL curve, (b) the 17-segment bull's-eye MW plots, (c) the comparison of GCW (green color) and GWW (blue color), and (d) the parameter reports of MW. PSL, pressure–strain loop; MW, myocardial work; GWI, global myocardial work index; GCW, global constructive work; GWW, global wasted work; GWE, global work efficiency; BP, blood pressure.

Figure 2

PSL and myocardial work parameters in improved and nonimproved LVEF patients. (a) PSL image in improved LVEF patients; (b) PLS image in nonimproved LVEF patients. PSL, pressure–strain loop; MW, myocardial work; GWI, global myocardial work index; GCW, global constructive work; GWW, global wasted work; GWE, global work efficiency; BP, blood pressure.

Figure 3

The ROC curve analysis of GCW and GWI. The figure shows the AUC of GCW and GWI by ROC curve. AUC, area under the curve; ROC, receiver operating characteristic; GCW, global constructive work; GWI, global myocardial work index.