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Acute coronary syndrome (ACS) is a set of cardiovascular diagnoses that have similar pathophysiology, which involves atherosclerosis of the coronary arterial system. Atherosclerotic plaque may become unstable and lead to the development of a thrombus. Depending on the degree of coronary artery occlusion from the thrombus, the patient may experience ischemia and/or infarction of the neighboring tissue supplied by the occluded coronary artery or arteries. Diagnosis of the ACS subtype is important to guide life-saving interventions such as percutaneous coronary interventions (PCI), which include percutaneous transluminal coronary angioplasty (PTCA), as well as stent implantation into the inflicted coronary arteries. Both types of PCI facilitate unobstructed or improved flow of the coronary circulation distally from a thrombus. The first step in the recognition of ACS is to understand the classic clinical presentation. As the word “acute” implies, all subtypes of ACS have a sudden onset, differentiating them from stable angina. A patient presenting with ACS typically describes crushing chest pressure with radiation to the jaw, arm, and shoulder. Patients may also have a combination of nonspecific symptoms including diaphoresis, nausea, vomiting, and a sense of illness (Table 4-1). The diagnosis of ACS is confirmed with electrocardiography (ECG), which differentiates T-wave changes, and/or ST-segment depressions seen with unstable angina (UA) and non-ST segment elevation myocardial infarctions (NSTEMI), from the ST-segment elevation observed with ST-segment elevation myocardial infarction (STEMI). Additionally, cardiac biomarkers (troponin, creatine kinase-MB) are used to further differentiate UA (negative troponins) from myocardial infarction (positive troponins) (Figure 4-1).

TABLE 4-1Signs and Symptoms of Acute Coronary Syndromea

Acute coronary syndromes treatment flowchart.


An estimated 16.5 million Americans more than or equal to 20 years of age has coronary artery disease (CAD), with a total prevalence of a 6.3%. The prevalence of MI (including both NSTEMI and STEMI) is 3%. Men have a higher prevalence with 7.4% compared to women at 5.3%. Due to the vast number of people afflicted with ACS ...

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