Strain Measurements in the Left Ventricle Vary Across Ultrasound Machines
Single segmental strain values should be used with caution in the clinic.
Contraction of the heart muscle generates strain, or deformation of tissue in response to force. Such so-called myocardial strain can be measured using echocardiography, a test that uses sound waves to create moving pictures of the heart. These measurements are useful for assessing the function of the left ventricle, providing diagnostic and prognostic value for a wide range of heart conditions. Global longitudinal strain, which is a measure of the deformation of the entire chamber, has proven to be a reproducible and valuable tool in clinical practice. However, data about the reproducibility and inter-vendor differences of segmental strain measurements, in which the left ventricle is divided up into segments to assess what is happening in each region, are missing.
To address this knowledge gap, researchers recently compared left ventricular segmental strain measurements obtained with six ultrasound machines and two post-processing software packages. As reported in a study published in the January issue of JACC: Cardiovascular Imaging, the researchers performed 882 echocardiographic examinations in 63 volunteers with myocardial segmental function ranging from normal to severely impaired. Images were acquired twice to assess test-retest variability.
Among the vendors, there were significant differences in image quality and the feasibility of assessing segmental strain, the measured segmental strain values, and the test-retest variability of segmental strain measurements. For example, the number of segments that could not be tracked with acceptable quality differed significantly between vendors, ranging from 7.1 percent to 22.9 percent. Moreover, the maximal absolute difference between the vendor with the highest and the lowest values was 4.5 percent for the measured strain parameters. According to the authors, the findings suggest that single segmental strain values should be used with caution in the clinic.