Assessment of stroke volume and cardiac output in real-world HF patients: a comparison of bioimpedance methods, 2D/3D echocardiography, and thermodilution in patients with sinus rhythm and AF
M Vitolo, N Bonini, M Mantovani, E Tartaglia, P Trapanese, B Corica, F Baldisserri, E Caliano, J Galloni, M Izzi, M Paolini, G Procaccia, M Ricchiuto, A Russo, G BorianiAbstract
Background
Thermodilution (TD) by right heart catheterization (RHC) represents the gold standard for stroke volume (SV) assessment. Several non-invasive approaches to assess SV, bio-impedance (NICaS®, total body bioimpedance, PhysioFlow®, thoracic bioimpedance) and echocardiography (2D and 3D-DHM 60/30), have been developed, but their accuracy, especially in atrial fibrillation (AF), remains uncertain.
Purpose
This study aims to compare in an unselected cohort of heart failure (HF) patients the agreement between these non-invasive SV assessment techniques with TD, evaluating their performance in sinus rhythm (SR) and AF.
Methods
SV was measured by TD, NICaS®, PhysioFlow®, 2D echocardiography, and 3D-DHM. Lin’s concordance correlation coefficient (CCC) and Pearson’s correlation (r) were used to assess agreement between each non-invasive method and TD, both in the overall cohort and in rhythm-specific subgroups.
Results
A total of 120 HF patients (median age 69 y.o., 46.7% female, median LVEF 40%) undergoing RHC were prospectively enrolled (Figure 1). According to cardiac rhythm at the time of the procedure, 70 patients were in SR (58%) and 50 in AF (42%), and AF patients were older and showed higher BNP and creatinine levels (Figure 1). Among SV measurements, AF patients exhibited a lower SV by TD, NICaS and 2D-ultrasound, not with the other methods. Overall, 2D echocardiography showed the highest agreement with TD for SV estimation (CCC=0.654; r=0.690, p<0.001). NICaS® demonstrated moderate concordance (CCC=0.536; r=0.550, p<0.001), while PhysioFlow® (CCC=0.388; r=0.460, p<0.001) and 3D-DHM (CCC=0.425; r=0.450, p<0.001) showed weaker correlations (Figure 2). When analyses were stratified by rhythm, all methods performed better in SR compared with AF. In the SR subgroup, 2D echocardiography maintained the best agreement with TD (CCC=0.621; r=0.670, p<0.001), followed by NICaS® (CCC=0.524; r=0.570, p<0.001). PhysioFlow® (CCC=0.375) and 3D-DHM (CCC=0.402) showed lower concordance with TD but still a significant correlation (Figure 2). In AF, 2D echocardiography had the highest concordance with TD (CCC=0.493; r=0.505, p=0.009), NICaS® preserved a moderate correlation (CCC=0.388; r=0.420, p=0.012), 3D-DHM lost statistical correlation (CCC=0.240, p=0.384) while PhysioFlow performance slightly reduced (CCC=0.305; r=0.480, p<0.001, Figure 2).
Conclusions
In a contemporary unselected cohort of HF patients undergoing RHC, 2D echocardiography showed the best agreement with TD for stroke volume. NICaS® showed moderate accuracy, whereas PhysioFlow® and 3D-DHM demonstrated weaker concordance. Overall, performance of all non-invasive techniques declined in AF, except for PhysioFlow®, highlighting the challenges of hemodynamic assessment based on current patients’ rhythm.Figure 1For image description, please refer to the figure legend and surrounding text.Figure 2For image description, please refer to the figure legend and surrounding text.