A novel clinical method for quantification of regional left ventricular pressurestrain loop area: a non-invasive index of myocardial work

Left ventricular (LV) pressurestrain loop area reflects regional myocardial work and metabolic demand, but the clinical use of this index is limited by the need for invasive pressure. In this study, we introduce a non-invasive method to measure LV pressurestrain loop area. Left ventricular pressure was estimated by utilizing the profile of an empiric, normalized reference curve which was adjusted according to the duration of LV isovolumic and ejection phases, as defined by timing of aortic and mitral valve events by echocardiography. Absolute LV systolic pressure was set equal to arterial pressure measured invasively in dogs (n 12) and non-invasively in patients (n 18). In six patients, myocardial glucose metabolism was measured by positron emission tomography (PET). First, we studied anaesthetized dogs and observed an excellent correlation (r 0.96) and a good agreement between estimated LV pressurestrain loop area and loop area by LV micromanometer and sonomicrometry. Secondly, we validated the method in patients with various cardiac disorders, including LV dyssynchrony, and confirmed an excellent correlation (r 0.99) and a good agreement between pressurestrain loop areas using non-invasive and invasive LV pressure. Non-invasive pressurestrain loop area reflected work when incorporating changes in local LV geometry (r 0.97) and showed a strong correlation with regional myocardial glucose metabolism by PET (r 0.81). The novel non-invasive method for regional LV pressurestrain loop area corresponded well with invasive measurements and with directly measured myocardial work and it reflected myocardial metabolism. This method for assessment of regional work may be of clinical interest for several patients groups, including LV dyssynchrony and ischaemia.