Left Ventricular Strain-Volume Loops in a Healthy Population: The Role of Sex and Age

By combining left ventricular (LV) global longitudinal strain (GLS) with LV volume during the cardiac cycle, LV strain-volume loops (SV-loops) can be generated. LV SV-loop derived parameters provide new insights into the interaction between cardiac contraction and volume in a variety of cardiac diseases and may even have prognostic value. The aim of this study is to describe SV-loops in a healthy adult population and investigate potential sex- and age-related differences of LV SV-loop characteristics.

In 125 healthy volunteers aged 18-72 years, apical 2-, 3- and 4-chamber views were acquired to measure GLS. Custom software was used to combine strain and volume data to construct SV-loops. Different parameters were derived: (i) linear slope of systolic strain-volume relation (S-Slope); (ii) linear slope of early-systolic strain-volume relation (ES-Slope); (iii) linear slope of early-diastolic strain-volume relation (ED-Slope); (iv) linear slope of late-diastolic strain-volume relation (LD-slope) and (v) uncoupling between systolic and diastolic strain-volume relation (UNCOUP).

For systolic strain-volume relation, higher values were observed in females compared to males, with S-Slope values of 0.19 %/mL m^-2 [0.17-0.22] and 0.13 %/mL m^-2 [0.11-0.14], respectively (p < 0.001). Similarly, ED-Slope was higher in females than in males, with values of 0.18 %/mL m^-2 [0.10-0.28] and 0.12 %/mL m^-2 [0.06-0.18] respectively (p = 0.003). Low values for uncoupling between the systolic and diastolic strain-volume relation were observed, with a mean value of 0.34 ± 1.1. Additionally, UNCOUP was positively correlated with age (r = 0.4; p < 0.05).

Higher values observed in systolic and early-diastolic strain-volume relation in females may reflect sex-specific differences in LV contraction. While the exact mechanisms remain unclear, these findings suggest potential variations in myocardial deformation patterns that warrant further investigation. Consistent with previous work, relative coupling of the systolic and diastolic strain-volume relationship was identified in our cohort of healthy individuals. However, with increasing age, higher values for uncoupling were observed, suggesting age-related alterations in ventricular mechanics that may contribute to changes in cardiac function over time.