Predictive Accuracy of Single-Beat Estimations of Left Ventricular Chamber Stiffness

Background: Gold standard measurements of left ventricular (LV) chamber stiffness require invasive hemodynamic assessment during manipulation of loading conditions. Given the technical challenges associated with this approach, minimally or non-invasive methods to predict LV chamber stiffness based on single-beat properties have been developed. However, the accuracy of these methods compared to LV stiffness measurements derived during load manipulation has not been directly studied. Objective: Compare serial single-beat LV chamber stiffness measurements to invasive measurements with load manipulation before and after the development of increased LV chamber stiffness in a porcine model of repetitive pressure overload (RPO). Methods: Serial invasive hemodynamic measurements of LV pressures and volumes were collected at rest and increased preload at baseline and after the development of increased LV chamber stiffness (n=5). Hemodynamic load manipulation-derived measurements of LV chamber stiffness were calculated by ∆LVEDP/∆LVEDV with echocardiographic volume measurements at rest (LVEDP ~12mmHg) and during elevated preload (LVEDP ~30mmHg) via intravenous phenylephrine. Resting echocardiography and LVEDPs were used to determine single beat predictions of LV chamber stiffness based on Klotz and Torres methods then compared to values determined from load manipulations. The Klotz method uses a single measured pressure-volume point at rest to predict LV volumes at 0 mmHg and 30mmHg to derive the end diastolic pressure volume relationship (EDPVR). The Torres method uses speckle tracking strain echocardiography alongside minimum and end-diastolic LV pressures to generate diastolic stress-strain relationships. Results: Load manipulations demonstrated that RPO produced a significant ~5-fold increase in LV chamber stiffness (from 0.34±0.01 mmHg/mL/m 2 to 1.68±0.22 mmHg/mL/m 2 , p< 0.01). However, the Klotz method did not show any significant change in the EDPVR beta coefficient from baseline to post-RPO (2.99±0.03 to 3.11±0.06, p=0.20). Similarly, the Torres method did not show a significant increase in global LV stiffness from baseline to RPO (0.44±0.18 to 0.30±0.06, p =0.34). Conclusions: Although single-beat estimations of LV mechanical properties have demonstrated utility in other models, they do not identify the increased LV chamber stiffness that is evident during load manipulation in swine subjected to chronic RPO. While invasive LV pressure-volume measurements and loading condition manipulations present their own challenges, they remain the ideal technique for assessing LV chamber stiffness. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.