Myocardial volume change during cardiac cycle derived from three orthogonal systolic strains: towards a quality assessment of strains

Background: The relative modification of the myocardial volume between end-systole and end-diastole ( $V_{s/d}=V_{\mathrm{end}-\mathrm{systole}}/V_{\mathrm{end}-\mathrm{diastole}}$ ) has already been assessed with different methods and falls in a range of 0.9-0.97 (mean value = 0.93).

Zweck: To estimate $V_{s/d}$ from the three longitudinal ( ${\varepsilon }_l)$ , circumferential ( ${\varepsilon }_c$ ), and radial ( ${\varepsilon }_r$ ) strains of the left ventricle using the formula: $V_{s/d}=(1+{\varepsilon }_c)(1+{\varepsilon }_r)(1+{\varepsilon }_l)$ and to test whether this estimate of $V_{s/d}$ can be used as a marker of the echocardiography quality.

Material and methods: Two hundred manuscripts, including a total of 34,690 patients or healthy volunteers, were identified in the Medline database containing values of ${\varepsilon }_l$ , ${\varepsilon }_c$ , and ${\varepsilon }_r$ measured from echocardiography.

Results: The median value of was 0.93, in accordance with the literature, with no significant difference between patients or healthy volunteers ( P = 0.38). The proportion of studies with $V_{s/d}=0.93\pm 0.1$ was 79%. When only considering groups of healthy volunteers, the studies failing this test had higher standard deviations for the three individual strains: 0.038 vs. 0.029 ( P = 0.02) for ${\varepsilon }_l$ ; 0.060 vs. 0.034 ( P < 10^-6) for ${\varepsilon }_c$ , and 0.243 vs. 0.101 ( P < 10^-14) for ${\varepsilon }_r$ .

Conclusion: The median ratio of the left ventricular myocardial volumes between end-systole and end-diastole in the investigated studies was $V_{s/d}=0.93$ . The formula $(1+{\varepsilon }_c)(1+{\varepsilon }_r)(1+{\varepsilon }_l)\notin [0.83;1.03]$ could be used to detect studies with inaccurate strain measurements.