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

Abstract

Background: Studies utilising invasive pressure‒volume loops offer valuable insights into left ventricular (LV) contractility, yet their availability remains limited. Conversely, noninvasive indices are accessible and reproducible; however, their validation in patients with aortic stenosis (AS) is lacking. We sought to validate the noninvasive indices of PVL studies in a group of symptomatic severe AS patients. We recruited patients with symptomatic severe AS admitted for transcatheter aortic valve implantation (TAVI) for invasive PVL studies. Noninvasive PVL indices were measured with three-dimensional (3D) echocardiography with a prespecified protocol. The agreement between invasive and noninvasive calculation methods was assessed. Results: Eleven patients (11) were recruited for this pilot study. The noninvasive end-systolic pressure‒volume relationship (ESPVR) determined by Kelly's method (Ees_(sb) = 0.9 × systolic blood pressure/end-systolic volume (ESV)) had the best agreement with the 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 × SBP/ESV) had 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.