Management of acute coronary syndrome is targeted against the effects of reduced blood flow to the affected area of the heart muscle, usually because of a blood clot in one of the coronary arteries, the vessels that supply oxygenated blood to the myocardium. This is achieved with urgent hospitalization and medical therapy, including drugs that relieve chest pain and reduce the size of the infarct, and drugs that inhibit clot formation; for a subset of patients, invasive measures are also employed (coronary angiography and percutaneous coronary intervention). Basic principles of management are the same for all types of acute coronary syndrome. However, some important aspects of treatment depend on the presence or absence of elevation of the ST segment on the electrocardiogram, which classifies cases upon presentation to either ST segment elevation myocardial infarction (STEMI) or non-ST elevation acute coronary syndrome (NST-ACS); the latter includes unstable angina and non-ST elevation myocardial infarction (NSTEMI). Treatment is generally more aggressive for STEMI patients, and reperfusion therapy is more often reserved for them. Long-term therapy is necessary for prevention of recurrent events and complications.
General principles Acute coronary syndromes are caused by a sudden, critical reduction in blood flow in one of the coronary arteries, the vessels that supply oxygenated blood to the myocardium (heart muscle), typically by a blood clot. The principal symptom is typically chest pain, known as angina pectoris; people who present with angina must prompt evaluation for possible acute coronary syndrome. Acute coronary syndromes are classified into two major categories, according to the patient's electrocardiogram, and specifically the presence or absence of persistent (>20 min) ST segment elevation (or left bundle branch block). Patients with acute coronary syndrome and ST elevation are said to have ST-elevation myocardial infarction (STEMI), and they tend to have one of their coronary arteries totally blocked. Damage is reversible for approximately 20-30 minutes after complete obstruction of blood flow; thereafter myocardial cell death ensues and progresses as time passes. Therefore, complete and sustained restoration of blood flow must be as prompt as possible to ensure maximum salvage of functional myocardium, a principle expressed in the maxim "time is muscle". This is achieved with reperfusion therapy, which is based on invasive reopening of the affected coronary artery with primary percutaneous coronary intervention, or non-invasive breaking up of the responsible blood clot with a thrombolytic drug. Patients without ST-segment elevation are said to have non-ST-elevation acute coronary syndrome and tend not to have full occlusion of a coronary artery. If there is evidence of myocardial cell death (especially elevated cardiac biomarkers), they are considered to have a non-ST-elevation myocardial infarction (NSTEMI); otherwise, they are classified with unstable angina. Their management is based on the estimation of their risk for adverse events. Patients at low risk can be adequately treated with medical therapy, in many ways similar to the one used for STEMI (but excluding thrombolytics). Those at moderate to high risk benefit from an early invasive strategy, which includes coronary angiography and, if necessary, revascularization with percutaneous coronary intervention or coronary artery bypass surgery. Medical therapy for acute coronary syndromes is based on drugs that act against ischemia and resultant angina and limit the infarct size (i.e., the area of myocardium affected), as well as drugs that inhibit clot formation. The latter include antiplatelet agents, which block the activation and aggregation of platelets (cellular blood components that contribute to clot formation), and anticoagulant agents (which attenuate the coagulation cascade). Long-term therapy in acute coronary syndrome survivors is targeted against recurrence and long-term complications (secondary prevention). Women are taken less seriously than men when they have a heart attack, leading to higher mortality among women.
Patient-dependent initial measures Because of the relationship between the duration of myocardial ischemia and the extent of damage to heart muscle, public health services encourage people experiencing possible acute coronary syndrome symptoms or those around them to immediately call emergency medical services. Patients with known coronary artery disease who have been prescribed nitroglycerin should promptly take one dose, and call emergency medical services if their symptoms do not improve within 2–5 minutes. Chewing non−enteric-coated aspirin is encouraged (unless there are contraindications). Patients should stay calm in a comfortable position. In case of heart attack, it would not usually be lying down, but sitting or sitting with folded knees (but patients would notice the position that fits for them). Patients should not be transported to the hospital by private vehicle instead of an ambulance, unless evacuation by land or air ambulance is impossible (e.g., dangerous weather in a very remote area), and if they must be, it should be done if possible with someone trained in cardiac first aid. Health care professionals are responsible for teaching their patients at risk of acute coronary syndrome what the symptoms of this condition are, and that it is imperative to seek urgent medical attention in case they present.
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