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When a patient is presented at the emergency department or to a mobile emergency system with acute chest pain, the first assessment includes a standard 12-lead electrocardiogram (ECG). When chest pain is caused by an acute coronary occlusion, the initial ECG can show ST-segment elevation, which meets the criteria that indicate an ST-segment elevation myocardial infarction (STEMI). All five patients included in this chapter presented with first-time STEMI due to an occluded left anterior descending coronary artery as documented by emergency coronary angiography (Fig. 21–1).
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The ECG is the initial modality used in the evaluation of patients with suspected acute myocardial infarction. It provides general information about presence and location of the acute ischemia/infarction process. Several ECG scoring systems are being used for assessment of the extent of the initially ischemic myocardium and also the extent of the final infarction. There are, however, limitations in using the ECG as a modality for sizing either the ischemic or infarcted region. In its current form, the ECG does not provide an image of the electrical activation or recovery. New methods are currently in development to transform the ECG waveforms into cardiac images, with algorithms to quantify key aspects of the ischemia/infarction process such as extent, acuteness, and severity.1-3
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The five patients included in this chapter represent the varied outcomes that can result from acute percutaneous coronary intervention (PCI) that is intended to provide maximal salvage of ischemic myocardium. The ECG was used to assess the Anderson-Wilkins Acuteness Score and the Sclarovsky-Birnbaum Severity Ischemia Grade on the initial ECG to indicate the patient's potential for recovery of the involved region of myocardium.4,5 Cardiovascular magnetic resonance (CMR) imaging was performed on all patients. Two patients received myocardial perfusion single photon emission computed tomography (SPECT) with the radioactive tracer injected prior to opening of the occluded vessel, and the other three patients received SPECT imaging with injection of the radioactive tracer only after the occluded vessel was opened. Positron emission tomography (PET) was performed on these three patients.
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In this chapter, the methods used for analysis will be described briefly, followed by description and visualization of the five presented patients. The category of outcome for each of the patients is also considered.
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Anderson-Wilkins Acuteness Score
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The ECG Anderson-Wilkins Acuteness Score indicates the acuteness of an episode of acute myocardial infarction on a continuous scale from ...