New work method for selecting patients for cardiac resynchronization therapy

The clinical standards for measuring left ventricular (LV) systolic function are LV ejection fraction (EF) and global longitudinal strain (GLS) with the latter as a more sensitive parameter to detect mild systolic dysfunction. There is abundance of documentation that LV EF is useful to guide clinical decisions, and there is emerging data showing clinical value of measuring GLS. A limitation of these modalities, however, is dependency on LV afterload and they do not provide information regarding efficiency of the ventricle.

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Myocardial work is calculated from non-invasive left ventricular pressure and strain by speckle tracking echocardiography. Myocardial work provides diagnostic information beyond what is achieved from left ventricular ejection fraction and strain since it incorporates afterload, and provides a measure of myocardial efficiency. The method can be used to calculate global as well as segmental work. The work method was recently shown to be of clinical value in selection of patients for cardiac resynchronization therapy. Several other clinical applications are currently tested.

Application of the work method should be explored in cancer patients as a means to diagnose therapy-related cardiac dysfunction or in patients with heart failure with preserved EF to demonstrate LV systolic dysfunction. Assessment of non-invasive myocardial work (MW) is obviously interesting in the field of ischaemic heart disease, hypertrophic or dilated cardiomyopathies for quantifying LV dyssynchrony and predicting outcome.

Finally, MW analysis should not be used in hypertrophic obstructive cardiomyopathy, since the intraventricular pressure gradient invalidates brachial artery pressure as estimate of peak LV pressure. For aortic stenosis, the mean aortic pressure gradient may be added to the brachial pressure. It remains to be studied if calculation of MW may play a role in aortic stenosis and if decrease in work may be a sign of LV decompensation.

How to measure left ventricular myocardial work bypressure–strain loops 
Eur Heart J Cardiovasc Imaging. 2021 Feb 22;22(3):259-261

Otto A Smiseth, Erwan Donal, Martin Penicka, Ole Jakob Sletten