Non-invasive myocardial work analysis – a potential novel echocardiographic tool for a better characterization of heart failure with preserved ejection fraction

Introduction: With every cardiac cycle, the heart de-mands myocardial energy consumption for onward propulsion of blood against arterial pressure. Myocar-dial work (MW) is calculated from the pressure-volu-me loop area. Similar, we can assess MW by echocar-diography, by including LV deformation on Speckle Tracking echocardiography (STE) with LV load. 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 conventio-nal and STE: 55 patients with DD (n=25) and HFpEF (n=30), and 25 normal subjects. We measured NT-proBNP, LV ejection fraction (LVEF) and E/E’ ratio. We used a new approach to calculate myocardial work, during mechanical systole and isovolumetric relaxati-on (IVR), by 2DSTE: global constructive work (GCW), performed during shortening in systole adding nega-tive work during lengthening in IVR; global wasted work (GWW), performed during lengthening in systo-le adding work performed during shortening in IVR; global work efficiency (GWE), as the constructive work divided by the sum of constructive and wasted work in% and global work index (GWI), as the GCW added to GWW. Similarly, a regional, segmental analysis was performed (18 segments model).

Results: LVEF was significantly higher in HfpEF group (58 ± 6 vs. 57 ± 8 vs. 63 ± 7, p=0.004). GCW increa-ses in patients with DD, probably as a compensatory mechanism to preserve LV function against an incre-ased after load, and decreases back to the normal va-lues in HFpEF (2295 ± 279 vs. 2550 ± 463 vs. 2300 ± 535mmHg%, p=0.05), while GWE significantly decrea-ses from normal subjects to patients with DD, and then further in patients with HFpEF (95.5 ± 1.8 vs. 94.8 ± 2.3 vs. 93.5 ± 2.5%, p=0.008). Meanwhile, GWW in-creases from normal subjects to patients with DD, and then further in patients with HFpEF (87.9 ± 39.6 vs. 108 ± 50 vs. 125 ± 51 mmHg%, p=0.019). As expec-ted, GWI does not change significantly (2102 ± 303 vs. 2296 ± 431 vs. 2074 ± 485 mmHg%, p=0.12). E/E’ was significantly higher in HfpEF group by comparison with DD and normals (10.3 ± 3.1 vs. 7.7 ± 2.4 vs. 7.3 ± 2.4, p<0.001), cu higher NTproBNP in HFpEF vs DD group (349 ± 418 vs. 36 ± 25, p<0.001). By segmental analysis, first segment affected in terms of myocardial work is basal antero-septal segment, with low WE and higher WW, 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).

Conclusions: Myocardial work efficiency decreases and wasted work increases with the severity of LV dys-function. The first myocardial segment affected is ba-sal antero-septal. Therefore, new parameters of myo-cardial work, derived from 2DSTE, might provide a better assessment of LV function in patients with DD or HFpEF.

ISSN – online: 2734 – 6382
ISSN-L 1220-658X
ISSN – print: 1220-658X
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CODE: 379
CME Credits: 10 (Romanian College of Physicians)