Assessment of Segmental Myocardial Viability Using Regional 2-Dimensional Strain Echocardiography

We determined whether 2-dimensional strain echocardiography can identify viable from infarcted myocardium in a rat ischemia-reperfusion model. A total of 16 male Sprague-Dawley rats underwent left anterior descending coronary artery occlusion for 12 or 30 minutes followed by 60-minute reperfusion. Short-axis 2-dimensional strain echocardiography was performed at the midventricle 60 minutes postreperfusion. Postsacrifice, triphenyl tetrazolium chloride was infused to the coronary circulation. Regional end-systolic radial and circumferential strain, and time to peak strain, were measured using software in all 96 segments and correlated with areas of infarct in corresponding histologic slices. Segments with greater than 50% area of infarct had lower end-systolic radial and circumferential strain and longer time to peak strain versus areas with 50% or less strain or no infarct. Extent of infarct correlates with radial and circumferential strain. End-systolic radial strain less than 2% has 88% sensitivity and 95% specificity for detecting infarcted area greater than 50%. Two-dimensional strain echocardiography-derived strain is useful in distinguishing infarcted from viable myocardium.