NONINVASIVE CHARACTERIZATION OF 3D MYOCARDIAL STRAIN IN MURINE LEFT VENTRICLES POST INFARCTION

Coronary artery disease remains the leading cause of death in the United States with over 1 million acute coronary events predicted to take place in 2019 alone. Heart failure, a common and deadly sequela of myocardial infarction (MI), is attributed to adverse ventricular remodeling driven by cardiomyocyte death, inflammation, and mechanical factors. Despite strong evidence suggesting the importance of myocardial mechanics in driving cardiac remodeling, many in vivo MI studies still rely on 2D analyses to estimate global left ventricular (LV) function and approximate strain using a linear definition. These metrics, while valuable in evaluating the overall impact of ischemic injury on cardiac health, do not capture regional differences in myocardial contractility. The objective of this work is therefore to expand upon existing ultrasound studies by enabling regional analysis of 3D myocardial strain. By integrating our recently developed four-dimensional ultrasound (4DUS) imaging technique with a direct deformation estimation algorithm for 3D strain, we identified unique remodeling patterns and regional strain differences between two murine models of MI with different infarct severities. By constructing 3D strain maps of the remodeling LVs, we were able to capture strain heterogeneity and characterize a sigmoidal strain profile at infarct border zones. Finally, we demonstrated that the maximum principal component of the 3D Green-Lagrange strain tensor correlates with LV remodeling severity and is predictive of final infarct size. Taken together, the presented work provides a novel and thorough approach to quantify regional 3D strain, an important component when assessing post-MI remodeling.