Modified Late Infarct Reperfusion to Prevent Post MI CHF

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DESCRIPTION (provided by applicant): Congestive heart failure (CHF) has reached epidemic proportions in the United States. The significant majority of these cases are the result of postinfarction LV remodeling. It is now established that early infarct expansion initiates an inexorable myopathic process in normally perfused myocardium that leads to a CHF. Infarct stiffening can prevent adverse remodeling and reperfusion therapy is currently the best available means to accomplish this. However, reperfusion therapy often fails to influence remodeling especially after long ischemic intervals. Much has been learned about pathophysiology and pathology of myocardial ischemia/reperfusion (I/R) but a comprehensive understanding of this very complex phenomenon has been illusive. It is not the central focus of this proposal to explore the mechanism of myocardial reperfusion injury (although the apoptosis studies will provide new information on how this unique form of cell death contributes to I/R injury) but rather to exploit what is already known to improve the results of reperfusion therapy for acute myocardial infarction. Our hypothesis is that even very limited myocardial salvage (too small to improve contractile function) within the area at risk can alter infarct material properties enough to prevent early infarct expansion, stabilize postinfarction ventricular geometry and prevent the development of CHF. A well-established sheep model of postinfarction ventricular remodeling and progressive CHF will be used. The effect of unmodified and modified reperfusion after varying ischemic intervals on infarct expansion and the outcome of remodeling will be assessed using the imaging techniques of sonomicrometry array localization and quantitative echocardiography. Myocytes are lost at the time of reperfusion due to necrosis, apoptosis and/or microvascular no reflow. Adenosine, abciximab and minocycline have been selected to modify the infarct reperfusate because they have been demonstrated in clinical and/or experimental studies and confirmed in the sheep model to limit infarct size within in the area at risk by affecting one or more of the mechanisms of cell loss that occur during myocardial ischemia/reperfusion.