Two-dimensional strain combined with adenosine stress echocardiography assessment of viable myocardium

The objective of this study was to explore a new method for the identification of viable myocardium by means of two-dimensional (2D) strain imaging combined with adenosine stress echocardiography. A total of 15 anesthetized open-chest healthy mongrel dogs underwent left anterior descending coronary artery occlusion for 90 min followed by 120-min reperfusion. Adenosine was infused at 140 μg kg⁻¹ min⁻¹ over a period of 6 min. Images were acquired at baseline (when pericardial cradle was made), after reperfusion (when reperfusion finished) and after adenosine administration (while administration stopped). Measurements of the regional peak-systolic strain in radial, circumferential, and longitudinal motion on anterior wall and anterior septum were, respectively, performed under different conditions. The dogs were killed after the echocardiographic studies finished and then the area of infracted myocardium was defined by triphenyltetrazolium chloride histology. A segment with equal or less than 50% area of infracted myocardium was considered to be viable. As a result, 37 regions were viable whereas 53 were non-viable among 90 regions in 15 dogs. At baseline, there was no significant difference in peak-systolic radial strain (Rs), circumferential strain (Cs), and longitudinal strain (Ls) between the viable and non-viable groups. After reperfusion, Rs, Cs, and Ls in absolute value decreased compared to those at baseline in both groups, although there was no significant difference between these groups. Rs and Ls increased after adenosine administration compared to reperfusion (p < 0.01; p < 0.05) in viable group while there were no changes in non-viable group. Compared with non-viable group Rs, Cs and Ls in viable group increased significantly (p < 0.01; 0.05) after adenosine administration. There was a negative correlation between Rs and infarct size (r = −0.72). Cs and Ls correlated well with infarct size, respectively (r = 0.40; 0.67). A change of Rs more than 13.5% has a sensitivity of 83.8% and a specificity of 83.0% for viable whereas a change of Ls more than 11% allowed a sensitivity of 78.4% and a specificity of 88.7%. Combined with these two variables, the sensitivity and specificity could reach 91.9 and 79.2%. Two-dimensional strain imaging combined with adenosine stress echocardiography can provide a new way to distinguish viable myocardium from the non-viable.