Acute coronary syndromes (ACS) are characterized by a sudden reduction in blood supply to the heart and include ST-segment elevation myocardial infarction (STEMI), non-STEMI (NSTEMI), and unstable angina. Each year, an estimated more than 7 million people in the world are diagnosed with ACS, including more than 1 million patients hospitalized in the US.
Chest discomfort at rest is the most common presenting symptom of ACS and affects approximately 79% of men and 74% of women presenting with ACS, although approximately 40% of men and 48% of women present with nonspecific symptoms, such as dyspnea, either in isolation or, more commonly, in combination with chest pain. For patients presenting with possible ACS, electrocardiography should be performed immediately (within 10 minutes of presentation) and can distinguish between STEMI and non-ST-segment elevation ACS (NSTE-ACS). STEMI is caused by complete coronary artery occlusion and accounts for approximately 30% of ACS. ACS without significant ST-segment elevation on electrocardiography, termed NSTE-ACS, account for approximately 70% of ACS, are caused by partial or intermittent occlusion of the artery and are associated with ST-segment depressions (approximately 31%), T-wave inversions (approximately 12%), ST-segment depressions combined with T-wave inversions (16%), or neither (approximately 41%). When electrocardiography suggests STEMI, rapid reperfusion with primary percutaneous coronary intervention (PCI) within 120 minutes reduces mortality from 9% to 7%. If PCI within 120 minutes is not possible, fibrinolytic therapy with alteplase, reteplase, or tenecteplase at full dose should be administered for patients younger than 75 years without contraindications and at half dose for patients 75 years or older (or streptokinase at full dose if cost is a consideration), followed by transfer to a facility with the goal of PCI within the next 24 hours. High-sensitivity troponin measurements are the preferred test to evaluate for NSTEMI. In high-risk patients with NSTE-ACS and no contraindications, prompt invasive coronary angiography and percutaneous or surgical revascularization within 24 to 48 hours are associated with a reduction in death from 6.5% to 4.9%.
Each year, an estimated more than 7 million people are diagnosed with ACS worldwide. For patients with STEMI, coronary catheterization and PCI within 2 hours of presentation reduces mortality, with fibrinolytic therapy reserved for patients without access to immediate PCI. For high-risk patients with NSTE-ACS without contraindications, prompt invasive coronary angiography followed by percutaneous or surgical revascularization is associated with lower rates of death.

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