Acute myocardial infarction (MI) is defined as myocardial ischemia, the inadequate supply of blood to heart muscle, followed by myocardial cell death. Multiple causes of acute MI are widely recognized and can be categorized as thrombotic, non-thrombotic, and acute MI secondary to coronary procedures. The mechanistic cause of a thrombotic MI is the rupture or erosion of an atherosclerotic plaque that results in the formation of a thrombus, or blood clot, which occludes the flow of blood. In contrast, non-thrombotic MI occurs secondary to mechanisms which create an oxygen supply and demand imbalance, but are not associated with atherosclerotic plaque rupture or disruption. Given that myocardial cell death is the pathological characteristic that is common to all acute MI, non-invasive diagnostics for acute MI are based on the detection of myocardial cell death. Currently non-invasive diagnostics for differentiating thrombotic MI from non-thrombotic MI do not exist which results in sub-optimal treatment and diminished patient safety. Further, it is not known how the impacts on metabolism and biological processes differ between thrombotic and non-thrombotic MI. In this project, we will address both of these problems. We will develop a diagnostic method for the non-invasive differentiation of thrombotic MI versus non-thrombotic MI that will enable earlier, safer, and more precise targeting of therapeutics to patients suffering from acute MI. We will determine biological processes that differ between thrombotic and non-thrombotic MI, which will suggest targets for therapeutic intervention that are specific to the underlying cause of an acute MI.
In Aim 1 we will utilize high resolution mass spectrometry to determine the absolute concentration of over 500 proteins in previously collected plasma samples from human subjects who were experiencing an acute MI for which the cause (thrombotic versus non-thrombotic) was determined. This will enable us to determine which proteins report on the cause of the acute MI as opposed to the presence of myocardial cell death. A critical advantage of our study design is that we have repeated measures from the same human subjects: at the time of presentation, 6 hours post-presentation, and at a stable event-free follow-up timepoint 3 months after the acute MI.
In Aim 2 we will integrate this data with our existing data on the abundances of metabolites and lipids generated from the same human subject samples. This integrated data will facilitate an in-depth analysis of the differences between thrombotic and non-thrombotic MI in the activities of metabolic pathways, receptor-ligand binding events, and other biochemical reactions. Further we will conduct data- dependent systems biology analyses that will highlight proteins, metabolites, and lipids that are co-abundant in plasma and will evaluate how the topology of these related entities differs between thrombotic and non- thrombotic MI.
In Aim 3 we will develop a statistical classifier for the determination of the underlying cause of an acute MI. We will conduct a blinded evaluation of the performance of this classifier in a second cohort.
Acute myocardial infarction (heart attack) is one of the leading causes of death in the United States and globally. Currently a non-invasive method of determining the underlying cause of an acute myocardial infarction does not exist, and it is unknown how different causes of acute myocardial infarction affect or alter metabolic processes. This project will use previously collected blood plasma from humans experiencing an acute myocardial infarction to develop a diagnostic method for determining the underlying cause of the event and how the different causes alter metabolic processes.
