Left Ventricular Mass Quantification by Echocardiography; a Novel Accurate and More Reproducible 2D-Method Validated by Cardiac Magnetic Resonance in Humans and Cardiac Autopsy in Pigs

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): The research fund of The Heart Center at Rigshospitalet, Denmark Background Left ventricular mass (LVM) is a strong independent risk factor for adverse cardiovascular events, but conventional echocardiographic methods used to assess and monitor individuals are currently limited by poor reproducibility and accuracy. Purpose We aimed to develop and validate an echocardiographic method for LVM-quantification that is simple, reproducible and accurate. Methods Our ‘novel method’ (Figure) adds the left ventricular wall thickness (t) to the left ventricular end-diastolic volume acquired by endocardial tracings using the biplane method of discs. For development of the novel method, cardiac assessment was performed using echocardiography followed immediately by gold standard cardiac magnetic resonance (CMR) in 85 humans with different left ventricular geometries, ranging from patients with various cardiac disorders (n = 41) to individuals without known cardiac disorders (n = 44). We compared the novel two-dimensional (2D) method to various conventional one-dimensional (1D) and 2D methods as well as three-dimensional (3D) echocardiography. Validation against anatomical LVM by cardiac autopsy was performed in thirty-four Danish Landrace pigs, weight 47-59 kg. Echocardiography was performed during anaesthesia, the pigs were euthanised, the heart explanted, and cardiac autopsy was performed where the left ventricle was trimmed and weighed for autopsy LVM. Results In humans, the novel method had better reproducibility in intra-examiner (coefficients of variation (CV) 8.6% vs. 11.0-14.5%) and inter-examiner analysis (CV 9.0% vs. 10.2-19.6%) than any other method, including 3D (CV intra-examiner 14.3%, inter-examiner 16.6%). Accuracy of the novel method against CMR was similar to 3D (mean difference ± 95% limits of agreement, CV): Novel: 2 ± 50g, 15.4% vs. 3D: 2 ± 51g, 15.6%; and better than the 1D-method by Devereux (7 ± 76g, 23.0%). Feasibility for the novel method was 95%. Autopsy validation in pigs confirmed high reproducibility; intra-examiner (CV 8.7% vs. 9.1-11.4%) and inter-examiner-analysis (CV 8.7% vs. 8.8-10.0%). Accuracy of the novel method against autopsy LVM was better than for the conventional echocardiographic methods: Novel -1 ± 20g, 7.8% vs. Devereux 26 ± 37g, 11.3%. 3D-validation was not available in pigs. Conclusions The novel 2D-based method for LVM-quantification had better reproducibility than any other echocardiographic method. Accuracy was similar to 3D and better than any conventional method. Autopsy validation in pigs supported our findings amongst the human population. As endocardial tracings using the biplane method forms part of the standard echocardiographic protocol, the novel method can easily be integrated into any echocardiographic software without substantially increasing analysis time, and provides an equivalent yet simpler alternative to 3D echocardiography. Abstract Figure.