Myocardial Work analysis reveals differential myocardial performance in patients with heart failure: A stress echocardiography study

Introduction: Myocardial work (MyW) analysis of transthoracic echocardiograms is a non-invasive method to provide information on the pressure-strain relationship of the left ventricle. To better understand pathohysiologic processes in heart failure (HF), we assessed myocardial performance during dynamic stress in patients with chronic HF and a reduced (HFrEF) or a preserved ejecton fraction (HFpEF), and compared them to healthy controls.

Methods and Results: The MyStress Pilot study enrolled 24 individuals including 12 well-characterized chronic HF patients (6 with HFrEF, 6 with HFpEF) and 12 healthy controls, aged 40-80 years, stratified by sex (1:1 ratio). Exercise stress echocardiography (ESE) was performed using a 45° tilted Schiller ERG 911 L ergometer, following a pre-specified protocol: start at 15 watts (W), followed by 15 W increments every 4 minutes, constant pedaling rate of 60/min. Echocardiographic images were analyzed using EchoPAC Version 202, GE. For the current analyses, we focused on measurements up to 75 W. To assess group differences and trends, we used generalized linear mixed models (GLMM) with random intercepts and slopes, applying ANOVA and post-hoc tests (Bonferroni or Tamhane) for comparisons between healthy controls, HFrEF, and HFpEF patients.

As shown in Table 1, HF patients were older than controls, but there were no differences in terms of body mass index, heart rate, blood pressure, and peripheral vascular resistance measured at rest. Patients with HFrEF achieved a median stress level of 75 W (quartiles: 53–98), similar to patients with HFpEF (75 W [68–75], p=0.818), but less than healthy controls (120 W, [105–146], p<0.001; Table 1).

At rest, MyW indices in HF patients were different from  healthy controls exhibiting lower constructive work in HFrEF and higher wasted work in both HF groups (Figure). During ESE, the amount of wasted work increased in all three groups. Constructive work and the work index increased with exercise in HFpEF and controls, but remained unchanged in HFrEF. These dynamics  resulted in different slopes of contructive work and work efficiency in HFrEF patients when compared to controls (Figure).

Conclusion

In our pilot study, we found differential myocardial performance as assessed by MyW in patients with HF and controls. These differences were apparent already at rest and persisted throughout exercise stress. Our results point towards HF subtype specific myocardial performance covered by MyW analysis, but need confirmation in larger patient cohorts.

Figure 1. Myocardial Work during Dynamic Exercise