Noninvasive cardiac output measurements are inaccurate in patients with severe aortic valve stenosis undergoing transcatheter aortic valve implantation

BACKGROUND: Noninvasive cardiac output (CO) measured using ClearSight™ eliminates the need for intra-arterial catheter insertion. The purpose of this study was to examine the accuracy of non-invasive CO measurement in patients with severe aortic stenosis (AS). METHODS: Twenty-eight patients undergoing elective transcatheter aortic valve implantation were prospectively enrolled in this study. The CO was simultaneously measured twice before and twice after valve deployment (total of four times) per patient, and the CO was compared between the ClearSight (CO(ClearSight)) system and the pulmonary artery catheter (PAC) thermodilution (CO(TD)) method as a reference. The Bland-Altman analysis was used to compare the percentage errors between the methods. RESULTS: A total of 112 paired data points were obtained. The percentage error between the CO(ClearSight) and CO(TD) was 43.1%. The paired datasets were divided into the following groups according to the systemic vascular resistance index (SVRI): low (< 1,200 dyne s/cm(5)/m(2)) and normal (1,200–2,500 dyne s/cm(5)/m(2)). The percentage errors were 44.9% and 49.4%, respectively. The discrepancy of CO between CO(ClearSight) and CO(TD) was not significantly correlated with SVRI (r = −0.06, P < 0.001). The polar plot analysis showed the trending ability of the CO(ClearSight) after artificial valve deployment was 51.1% which below the acceptable cut-off (92%). CONCLUSIONS: The accuracy and the trending ability of the ClearSight CO measurements were not acceptable in patients with severe AS. Therefore, the ClearSight system is not interchangeable with the PAC thermodilution for determining CO in this population.