(231) Ventriculoarterial Coupling in the High-Acuity Population

Introduction: Ventriculo-arterial coupling (VAC) encapsulates the interactions of cardiac and vascular mechanics in disease and health. Gold-standard measurements of the VAC require invasive hemodynamic testing but echocardiographic approaches have been described. However, these may present challenges in critically ill patients with perturbed cardiovascular physiology and poor acoustic windows. We hypothesized that tissue Doppler-based surrogates of VAC would correlate strongly with currently accepted echocardiographic calculations of the VAC ratio among both ambulatory and critically ill patients.

Methods: We conducted a retrospective cohort study of patients who had an echocardiogram performed between 2018-2023 within Gundersen Health System. We had two cohorts ambulatory outpatients and Critical Care Unit (CCU) inpatients, who had an echocardiogram within 12 hours prior or up to 24 hours after admission to the CCU. VAC was calculated using a validated single-beat method (Chen method) and a published simplified equation based on left ventricular ejection fraction (EF method). We also calculated two VAC surrogates based on noninvasively measured arterial elastance, e’ velocity, and mitral s’ velocity (TDI surrogates). We extracted echocardiographic variables from formal reports, and we measured the remaining variables from tissue Doppler tracings. Our primary outcome was the correlation of noninvasively determined VAC ratios (Chen and EF methods) and surrogates using Pearson’s coefficient.

Results: Our cohorts included 259 ambulatory outpatients and 221 CCU inpatients. Among CCU patients, 127 (57%) were hypotensive in the first 24 hours of CCU admission, 80 (36%) required inotropes, and 188 (85%) survived to hospital discharge. We found modest correlation between the previously described Chen and EF methods in ambulatory patients (Pearson’s r = 0.63, p < 0.001) but a weak correlation in the CCU patients (Pearson’s r = 0.28, p< 0.001). In both cohorts, our proposed TDI surrogates had negligible correlations with the Chen method of calculating VAC ratio. However, our mitral s’-based TDI surrogate of VAC and the EF method for calculating VAC ratio had moderate correlation (Pearson’s r = 0.58, p < 0.001).

Conclusions: Simplified methods of quantifying VAC perform poorly in high acuity patients admitted to CCU.