Ventricular-arterial coupling during exercise and tilt assessed using a pulse wave velocity-to-global longitudinal strain ratio.

Ventricular-arterial coupling (VAC) is commonly assessed using the echocardiography-derived ratio of arterial elastance to end-systolic elastance (Ea/Ees), a convenient but global construct that collapses ventricular and arterial properties into a single lumped parameter. A proposed index, combining pulse wave velocity and global longitudinal strain (PWV/GLS), provides a mechanistically grounded representation of coupling by directly integrating measures of arterial stiffness and myocardial deformation. This study compared the ability of Ea/Ees and PWV/GLS to discriminate between acute physiological stress conditions. Twenty healthy young adults (10 females; 23 ± 2 yr) completed a randomized crossover-graded cycling protocol (25 and 75 W; fixed heart rate ∼130 beats/min) in supine and 20° head-up tilt (HUT). HUT induces changes in ventricular volume loading, thereby challenging inherent assumptions underlying Ea/Ees. Ea/Ees progressively declined with increasing exercise intensity (main effect of stage P < 0.01; all P < 0.05 from previous stage), reflecting increased left ventricular elastance (Ees) relative to arterial load (Ea). Ea/Ees showed no detectable differences between supine and HUT either at rest or at any exercise stage (interaction P > 0.05). In contrast, PWV/GLS was less sensitive to exercise intensity (all stages only different from baseline P < 0.05) but showed a difference from supine to HUT at rest (P < 0.01). These findings support a context-dependent approach to VAC assessment: Ea/Ees reflects volumetric-pressure coupling during exercise, whereas PWV/GLS was responsive to fluid shifts and preload changes, supporting its potential as an alternative VAC measure that captures arterial wave propagation and myocardial deformation when the assumption of a negligible volume intercept (V0) is challenged.NEW & NOTEWORTHY This study evaluates ventricular-arterial coupling using traditional Ea/Ees and a novel pulse wave velocity/global longitudinal strain (PWV/GLS) ratio during exercise and head-up tilt. Ea/Ees decreased with graded exercise but was insensitive to postural stress. In contrast, PWV/GLS detected tilt-related changes at rest but showed dampened responsiveness to exercise intensity. These findings demonstrate complementary, context-dependent behavior of coupling metrics and support investigating alternative noninvasive methods to better resolve coupling under dynamic physiological conditions in healthy adults.