P736 Feasibility and accuracy of real-time automatic quantification of left ventricular ejection fraction by hand-held ultrasound device
Authors: Hjorth-Hansen A , Magelssen M S , Anderssen G N , Graven T , Kleinau J O , Mjolstad O C , Skjetne K , Dalen H 
Published: January 2020

Abstract

Funding Acknowledgements
This study is perfomed with loan of hand-held devices and technical support by GE Ultrasound. The study was financed by NTNU and Levanger Hospital

Background
Automatic quantification of left ventricular (LV) ejection fraction (EF) by hand-held ultrasound devices (HUDs) may increase the benefit of focused cardiac ultrasound by inexperienced users. Automatic measurements of EF (autoEF) from 4-chamber (4Ch) recordings are available for real-time use. Image quality is of major importance for EF assessment, but the influence of automatic quantification of LV function by HUD is not evaluated.

Purpose
To evaluate the feasibility and accuracy of autoEF for real-time quantification of LV function by HUDs, and to assess the importance of image quality and the operators’ experience for the accuracy of the method.

Methods
Patients referred to a cardiac outpatient clinic with suspected heart failure (HF) were included. In total, 5 GPs, 3 nurses and 5 cardiologists performed HUD examinations. Each patient was examined by a nurse and a general practitioner (GPs) using a HUD. Immediately thereafter, a cardiologist performed echocardiographic reference examination and a HUD examination for autoEF. The GPs underwent six pre-study practical training days in addition to lectures. The nurses were familiar with focused cardiac ultrasound from their work at the outpatient HF clinic. AutoEF was measured in 4Ch view only. Reference EF was measured by the cardiologists using the biplane Simpson’s method. Another cardiologist blinded to the reference measurements and operators evaluated each HUD recording on technical and qualitative parameters using a scale from 1 (poor) to 6 (very good), and recommended to accept or reject the autoEF result. In total, 510 recordings of autoEF were available for analysis.

Results
87 patients (46% women) with mean age of 67.5 years were examined. Mean BMI was 29 kg/m2, 95% CI (27.5, 30.2). 24 (30%) had atrial fibrillation. Of 510 recordings with autoEF measurements, 255 (50%) were rejected during evaluation and considered not eligible for clinical use. AutoEF by HUD and refEF was mean (SD) 52.6% (16.7) and 53.2% (7.3), respectively. Overall, the quality score for autoEF recordings was mean (SD) 4.4 (0.9). The highest mean score was 5.0 (SD 0.7) by the cardiologist and lowest for the GPs 4.0 (SD 0.9) (p &lt; 0.001). The corresponding proportions of accepted autoEF measurements were 75% and 33%, respectively. The difference compared to reference were lowest in the accepted recordings (p &lt; 0.001). The most important parameters for correct autoEF measurements were a properly assessed 4Ch view, a well visualized mitral annulus and the number of segments with visible endocardium (all p &lt; 0.01), the latter being the overall most important parameter.

Conclusion
The feasibility of evaluation of real-time automatic assessment of LV EF by HUD was only moderate. In the hands of the least experienced the use of automatic LV EF was not of adequate quality compared to reference. Thus, sufficient training and good image quality is essential for automatic assessment of LV function by HUDs.