Fig 1.
Echocardiographic scanner and analytic software used in this study with example strain curves from one patient reporting global longitudinal strain (GLS), mechanical dyssynchrony index (MDI) and post-systolic shortening index (PSI).
Fig 2.
Schematic representation of Strain curves demonstrating (a) method of calculation of segmental post-systolic shortening index and time to peak strain and (b) relationship between global mechanical dispersion index and post systolic strain index. Panel A shows a single time-delayed segmental strain curve with values of peak end-systole strain (global) and maximum post-systolic strain marked by arrows. From these values, segmental post systolic strain index is calculated as: 100% × (maximum post-systolic strain–end-systole strain)/maximum post-systolic strain. If no regional post systolic strain present, its post-systolic strain index is 0. Time to peak interval, used to calculate mechanical dispersion index, and is represented by a broken arrow. Panel B shows four segmental strain curves dispersed in time and displayed as dashed lines, with their point-by-point average represented as a full black line. Two segmental strains peaking before end systole and having zero post systolic shortening are marked by blue arrows, while two segmental strains peaking after end systole and thus exhibiting post systolic shortening are marked by red arrows. Global post systolic shortening index is then calculated as the mean of segmental systolic shortening indices. Mechanical dispersion index is calculated as the standard deviation of segmental time-to-peak intervals. By default, absence of mechanical dispersion means absence of post-systolic shortening and vice versa.
Fig 3.
Comparison of post-systolic shortening index averaged across all strain software between controls, hypertrophic cardiomyopathy (HCM) and cardiac amyloidosis patients (top) and examples of post-systolic shortening index plots for healthy control, hypertrophic cardiomyopathy (HCM) and cardiac amyloidosis patients (bottom).
Table 1.
Cohort clinical and echocardiography characteristics.
Fig 4.
Post-systolic shortening index (PSI) by strain software in (a) all patients, (b) healthy controls, (c) hypertrophic cardiomyopathy (HCM), and (d) cardiac amyloidosis.
Fig 5.
Correlation scatterplots between post-systolic shortening index and (a) mechanical dispersion index, (b) QRS duration and (c) left ventricular global longitudinal strain.