127 Early ischemia identified by the wasted energy using speckle tracking analysis

PurposePost systolic shortening (PSS) and stretching motion occur early during ischemia. Delayed contraction in PSS and stretching motion does not fully contribute to left ventricular end systolic (ES) function and contribute to the left ventricular dysfunction. The wasted energy can be quantified as the difference between peak strain and end systolic strain and used to identify ischemic segments.MethodsAcute myocardial ischemia was induced in 9 anesthetized pigs by balloon coronary occlusion (left coronary descending artery, n=6). Circumferential strain by speckle tracking was computed from short axis view during ischemia at 5’, 30’and 60’. PSS was defined as peak strain occurring after ES and stretching motion as positive systolic peak strain.ResultsBefore induced ischemia, PSS was observed in 38% segments and stretching motion was low (0±1%), then the wasted energy was limited (1±0%). During acute (5’) and prolonged (60’) coronary occlusion, stretching motion increased (4±2% at 5’, and 8±2% at 60’) and PSS became more prevalent (54% and 54%, respectively) and delayed in ischemic segment (3% and 12% of RR interval, respectively). This result the wasted energy was greater in ischemic than non ischemic segment (5±1% vs. 1±1% at 5’, p<0.001, 9±1% vs. 2±1% at 60’ p