121 Assessment of contractile reserve using strain delay index by speckle tracking to identify myocardial viability

BackgroundIn dysfunctional segment, contractility in delayed segments does not fully contribute to end-systolic function. This reserve of contraction (strain delay index) related to mechanical dyssynchrony is supposed to be greater in viable and ischemic segments than in infarct segments.MethodsPercutaneous coronary occlusion (circumflex) was performed in 13 anesthetized pigs to investigate changes in strain delay index during acute ischemia (after 3’ of occlusion) and after induced myocardial necrosis (>2 hours of occlusion). The strain delay index, which was defined as the difference between peak and end-systolic strain was computed from circumferential and radial strain curves obtained by speckle tracking analysis performed on short axis view.ResultsIn related coronary occluded segments, delayed myocardial contraction and impaired regional peak strain was observed during early ischemia for circumferential and radial strain. However, despite prolonged coronary occlusion, delayed contraction and peak circumferential and radial strain remained unchanged. In contrast, regional strain delay index showed a biphasic pattern with an increased during early ischemia and a significant decrease after a prolonged coronary occlusion.ConclusionsDelayed myocardial contraction and reduce peak strain by speckle tracking can be similarly observed during early and prolonged coronary occlusion. In contrast, regional strain delay index used to quantify contractile reserve appears to more sensitive to identify myocardial viability