The Validation of Non-Invasive Pressure-Volume Loop Indices in Severe Aortic Stenosis

Background: Studies utilizing invasive pressure-volume loops offer valuable insights into left ventricular (LV) contractility, yet their availability remains limited. Conversely, non-invasive indices are accessible and reproducible; however, their validation in aortic stenosis (AS) is lacking. We sought to validate the non-invasive indices of PVL studies in a group of symptomatic severe AS. Methods: We recruited patients with symptomatic severe AS admitted for trans-catheter aortic valve replacement (TAVR) to undergo invasive PVL studies. Non-invasive PVL indices were measured with three-dimensional (3D) echocardiography with a pre-specified protocol. The agreement between invasive and non-invasive calculation methods were assessed. Results: Eleven patients (11) were recruited for this pilot study. The non-invasive end-systolic pressure-volume relationship (ESPVR) Kelly's method (Ees(sb) = 0.9 x systolic blood pressure/end-systolic volume (ESV)) had the best agreement with invasive ESPVR (limits of agreement -1.7 to 2.1 with a percentage error of 24%, one sample T-test p =0.504). Systolic blood pressure, as measured by the brachial blood pressure cuff, had the best agreement with end-systolic pressure in severe aortic stenosis (limits of agreement -60 to 60 with a percentage error of 3%, one sample T-test p =0.959). Conclusion: Measurement of the single-beat estimate of ventricular elastance (Ees(sb)) is possible in patients with severe aortic stenosis. Kelly's method (Ees(sb) = 0.9 x SBP /ESV) has the best agreement with the invasive measurement of left ventricular elastance (Ees). Systolic blood pressure, as measured by the brachial blood pressure cuff, has the best agreement with end-systolic pressure in severe aortic stenosis. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement None to declare ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Approvals of the original study design and subsequent amendments were all granted by London - Dulwich Research Ethics Committee with the reference number: 13/LO/1542 IRAS project ID: 123464. All study participants gave a written consent. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data is available upon request