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EPIDEMIOLOGY

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Ischemic heart disease is the leading cause of morbidity and mortality in Western society and is a worldwide epidemic. In 2008, it was estimated that, worldwide, ischemic heart disease was responsible for 12.7% of all deaths (7.25 million total) with low-income countries now accounting for 80% of all deaths with a falling mortality in high-income countries.1 Approximately 1,100,000 Americans suffer from an acute coronary syndrome (ACS) per year, nearly one-third of which are caused by an acute ST-segment elevation myocardial infarction (STEMI).2 The incidence of acute myocardial infarction (AMI) has declined over the past two decades from 244 per 100,000 population in 1975 to 162 per 100,000 population in 2006.3 The in-hospital mortality rate also has declined from 18% in 1975 to 10% in 2006.4 Despite these improvements, AMI continues to be a major public health problem, and it has been estimated that the number of years of life lost because of an AMI is 17.1 years, and the cost to American society (both direct and indirect) is $165.4 billion per year.2

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The management of STEMI patients is complex, multidisciplinary, and involves the following four different stages of care: (1) prehospital care, (2) emergency department, (3) cardiac catheterization laboratory, and (4) coronary care unit. This chapter discusses the diagnosis and management of STEMI patients in each of these four settings. The pathophysiology of disease is discussed in Chap. 37, and the ACSs of unstable angina and non–ST-segment elevation myocardial infarction are discussed in Chap. 39.

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DIAGNOSIS

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Symptoms

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The classic symptom of acute myocardial ischemia is precordial or retrosternal discomfort, commonly described as a pressure, crushing, aching, or burning sensation. Radiation of the discomfort to the neck, back, or arms frequently occurs, and the pain is usually persistent rather than fleeting. The discomfort typically achieves maximum intensity over several minutes and can be associated with shortness of breath, nausea, diaphoresis, generalized weakness, and a fear of impending death. Some patients, particular the elderly, may also present with syncope, unexplained nausea and vomiting, acute confusion, agitation, or palpitations. Symptoms in the advanced elderly (> 75 years old) are more likely to be atypical (new or worsening dyspnea) than in younger patients and can lead to a missed diagnosis if a medical professional is not vigilant in the initial assessment.

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Approximately 20% of AMI patients are asymptomatic or have atypical symptoms that are not initially recognized. Painless myocardial infarction occurs more frequently in the elderly, women, diabetics, and postoperative patients. These patients tend to present with dyspnea or frank congestive heart failure as their initial symptom.5 Some patients with ST-segment elevation do not have occlusive thrombosis and have a unique regional cardiomyopathy called takotsubo syndrome, which is described at the end of the chapter.

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Physical Examination

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Patients often appear anxious and uncomfortable. Those with ...

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