P2606Analysis of myocardial work: a potential new tool for a better assessment of left ventricular function

Abstract

Abstract Background Left ventricular (LV) deformation is dependent on mechanical load and does not reflect directly the myocardial energy consumption. Thus, measurement of global and regional myocardial work might be alternative and complementary methods for the assessment of myocardial function. However, there is no data regarding myocardial work changes during the heart failure continuum, from normal to diastolic dysfunction (DD), and to heart failure with preserved ejection fraction (HFpEF). Methods We assessed 80 subjects by 2D conventional and speckle tracking echocardiography (2DSTE): 25 patients with DD, 30 with HFpEF, and 25 normal, control subjects. We measured NTproBNP, LV ejection fraction (EF), and E/E' ratio. We used a new approach to calculate myocardial work, during mechanical systole and isovolumetric relaxation, by 2DSTE: global constructive work (GCW), as the “positive” work of the heart; global wasted work (GWW), as the “negative” work of the heart; global work efficiency (GWE), as the GCW/(GCW + GWW) in %; and global work index (GWI), as the GCW added to GWW. Similarly, a regional, segmental analysis was performed (18 segments model) (Figure 1). Results GCW increases in patients with DD, probably as a compensatory mechanism to preserve LV function against an increased after load, and decreases back to the normal values in HFpEF, while GWE significantly decreases from normal subjects to patients with DD, and then further in patients with HFpEF (table). Meanwhile, GWW increases from normal subjects to patients with DD, and then further in patients with HFpEF. As expected, GWI does not change significantly. By segmental analysis, first segment affected in terms of myocardial work is basal antero-septal segment, with low WE and higher WW (figure), probably due to the flat shape (based on the Laplace law), with a compensatory increased CW in the apical segments. NTproBNP level and E/E' ratio correlated only with GWW (r=0.4, p=0.013). Comparative global myocardial work Group LVEF (%) E/E' NTproBNP (pg/ml) GWI (mmHg%) GWE (%) GCW (mmHg%) GWW (mmHg%) Controls 58±6 7.3±2.4 – 2102±303 95.5±1.8 2295±279 87.9±39.6 DD 57±8 7.7±2.4 36±25 2296±431 94.8±2.3 2550±463 108±50 HFpEF 63±7 10.3±3.1 349±418 2074±485 93.5±2.5 2300±535 125±51 P (Anova) 0.004 <0.001 <0.001 0.12 0.008 0.05 0.019 Figure 1. Myocardial Work Conclusion Myocardial work efficiency decreases and wasted work increases in parallel with the severity of LV dysfunction. The first myocardial segment affected is basal antero-septal. Therefore, new parameters of myocardial work, derived from 2DSTE, might provide a better assessment of LV function in patients with DD or HFpEF. Acknowledgement/Funding This work was supported by a grant of Ministery of Research and Innovation, CNCS-UEFISCDI, project number PN-III-P1-1-TE-2016-0669, within PNCDI III