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Acute coronary syndrome (ACS) is a spectrum of coronary artery disease (CAD) with similar pathophysiology involving a myocardial oxygen and supply–demand mismatch, secondary to atherosclerosis of the coronary arterial system. During ACS, atherosclerotic plaque may become unstable and lead to the development of a thrombus. Depending on the degree of coronary artery stenosis from the thrombus, the patient may experience ischemia and/or infarction of the neighboring tissue supplied by the stenotic coronary artery or arteries.

Diagnosis of the ACS subtype is important to guide lifesaving interventions such as fibrinolysis and/or percutaneous coronary interventions (PCIs). PCI includes percutaneous transluminal coronary angioplasty (PTCA) and/or 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 angina as substernal crushing chest pressure with radiation to the jaw, arm, and/or shoulder. Patients may also experience a combination of nonspecific symptoms including diaphoresis, nausea, vomiting, and an impending sense of doom (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 infarction (MI) (NSTEMI), and from the ST-segment elevation or new left bundle branch block (LBBB) observed with ST-segment elevation MI (STEMI). Additionally, cardiac biomarkers (ie, troponin) are used to further differentiate unstable angina (negative troponins) from an MI (positive troponins). Figure 4-1 describes the management of ACS.


Acute coronary syndromes treatment flowchart

TABLE 4-1Signs and Symptoms of Acute Coronary Syndrome


CAD A risk calculator can be used to predict a patient’s incidence of an atherosclerotic cardiovascular disease (ASCVD)-related event. The risk calculator evaluates gender, age, race, total cholesterol (or treatment with cholesterol-lowering medications), HDL, hypertension (or current treatment for hypertension), cigarette smoking, and history ...

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