Antiplatelets are prescribed for a variety of conditions, including:

• Coronary artery disease. Antiplatelets may help to prevent a heart attack or stroke in patients who are at high risk of developing obstructive blood clots (coronary thrombosiscoronary thrombosis). Aspirin has been shown to prevent first heart attacks in middle-aged men who are asymptomatic and without any known heart disease.  However, the recent CHARISMA study showed that certain antiplatelets do not provide a benefit to middle-aged people without known heart disease.
  
  
• Heart attack. An event in which the heart muscle does not receive enough oxygen-rich blood as a result of a blockage in the coronary blood vessels. Antiplatelets may reduce the damage to the heart if taken while an attack is in progress or immediately afterward (preferably within 30 minutes). Recent research also indicates that a combination of aspirin and other antiplatelets administered after a heart attack may reduce the risk of death, stroke or another heart attack.
  
  
• Angina. A temporary and often recurring chest pain, pressure or discomfort caused by inadequate oxygen-rich blood flow (ischemia) to some parts of the heart.
  
  
• Stroke. An event in which the brain does not receive enough oxygen-rich blood, usually due to blockage of a cerebral blood vessel by a blood clot. In high-risk patients, taking antiplatelets regularly has been found to prevent the formation of blood clots that cause first or second strokes. However, patients should not take aspirin or any other antiplatelet during a suspected stroke because it may cause further damage. Antiplatelets are contraindicated when the stroke is associated with brain hemorrhage or when the brain is likely to develop hemorrhagic transformation.
  
  
  
  
  
• Transient ischemic attacks (TIAs, or mini-strokes). A brief interruption of oxygen to the brain due to decreased blood flow through the arteries, usually because of an obstructing blood clot. Antiplatelet drugs have been found to be effective in the prevention of TIAs, and they also help prevent against ensuing strokes. TIAs are considered a major warning sign of impending stroke.
  
  
• Angioplasty. A catheter-based technique used to open arteries obstructed by a blood clot. Whether or not stenting is performed immediately after this procedure to keep the artery open, antiplatelets may reduce the risk of forming additional blood clots following the procedure(s). Aspirin and clopidogrel can reduce the chance of heart attack and death, especially if taken several hours before the procedure. 

• Coronary bypass surgery. A surgical procedure in which an artery or vein is taken from elsewhere in the body and grafted to a blocked coronary artery, rerouting blood around the blockage and through the newly attached vessel. After the procedure, antiplatelets may reduce the risk of secondary blood clots.
  
  
• Atrial fibrillation. The most common type of sustained abnormal heart rhythm (arrhythmia), atrial fibrillation affects about 2 million Americans every year. During atrial fibrillation, the atria (the heart’s upper chambers) rapidly fire electrical signals that cause them to quiver rather than contract normally. This may lead to the creation of blood clots within the atria that can travel to the brain or other organs (embolism), potentially causing a stroke. Antiplatelets may reduce this risk. However, most patients with atrial fibrillation need to take anticoagulants because antiplatelets alone are not sufficient to reduce the risk of an embolism.