Unstable angina is a type of acute chest pain that occurs when your heart doesn't get enough oxygen. It can be a warning sign of a heart attack.

See also:

• Stable angina
• Variant angina

Coronary artery disease due to atherosclerosis is by far the most common cause of unstable angina. Atherosclerosis is the build up of fatty material called plaque along the walls of the arteries. This causes arteries to become less flexible and narrow, which interrupts blood flow to the heart, causing chest pain.

At first, angina may be considered stable -- that is, the chest pain only occurs with activity or stress. Unstable angina is chest pain that is sudden and gets increasingly worse. The chest pain:

• Occurs without cause (for example, it wakes you up from sleep)
• Lasts longer than 15 - 20 minutes
• Responds poorly to a medicine called nitroglycerine
• May occur along with a drop in blood pressure or significant shortness of breath

A coronary artery spasm is a rare cause of angina.

Risk factors for unstable angina are similar to those for stable angina and coronary artery disease. They include:

• Being male
• Diabetes
• Getting older
• Family history of coronary heart disease before age 50
• High blood pressure
• High LDL cholesterol
• Low HDL cholesterol
• Not getting enough exercise
• Smoking
• Obesity

Symptoms include:

• Sudden chest pain that may also be felt in the shoulder, arm, jaw, neck, back, or other area
• Pain that feels like tightness, squeezing, crushing, burning, choking, or aching
• Pain that occurs at rest and does not easily go away when using medicine

If you have stable angina, and the chest pain starts to feel different, lasts longer than 15 - 20 minutes, or occurs at different times, you may be developing unstable angina.

The doctor will perform a physical examination and check your blood pressure. The doctor may hear abnormal sounds, such as a heart murmur or irregular heart beat, when listening to your chest with a stethoscope.

Tests to diagnose angina include:

• Blood tests to check the levels of creatine phosphokinase (CPK), myoglobin, and troponin I and T
• Coronary angiography
• ECG
• Echocardiography
• Stress tests

Your doctor may want you to check into the hospital to get some rest and prevent complications.

Blood thinners (antiplatelet drugs) are commonly used to treat and prevent unstable angina. Such medicines include aspirin and the prescription drug clopidogrel. The two medicines are often used together. Aspirin (and sometimes clopidogrel) may reduce the chance of heart attack in certain patients.

During an unstable angina event, you may receive heparin and nitroglycerin. Other treatments may include medicines to control blood pressure, anxiety, abnormal heart rhythms, and cholesterol.

Some people may need CABG (coronary artery bypass grafting) or angioplasty with stenting. Angioplasty with stenting does not help you live longer than just taking medicine, but it can reduce angina or other symptoms of coronary artery disease. Angioplasty with stenting, however, can be a life-saving procedure if you are having a heart attack

How well you do depends on many different things, including:

• The severity of coronary artery disease
• The severity of the most current unstable angina attack
• Whether you've ever had a heart attack
• The medicines you were taking when the angina attack started

Arrhythmias and heart attacks can cause sudden death.

Unstable angina may lead to a heart attack.

Call your health care provider if you have any symptoms of angina.

If you think you are having a heart attack, seek immediate medical treatment.

Lifestyle changes can help preventing some angina attacks. Your doctor may tell you to:

• Stop smoking
• Lose weight if you are overweight

You should also keep strict control of your blood pressure, diabetes, and cholesterol levels. Some studies have shown that making a few lifestyle changes can prevent blockages from getting worse and may actually improve them.

If you have one or more risk factors for heart disease, talk to your doctor about possibly taking aspirin or other medicines to help prevent a heart attack. Aspirin therapy (75 - 325 mg a day) or a drug called clopidogrel may help prevent heart attacks in some people. Aspirin therapy is recommended if the benefit is likely to outweigh the risk of gastrointestinal side effects.

Boden WE, O'rourke RA, Teo KK, et al. Optimal Medical Therapy with or without PCI for Stable Coronary Disease. N Engl J Med. 2007 Mar 26; [Epub ahead of print].

Braunwald E, Antman EM, Beasley JW, et al. ACC/AHA Guideline Update for the Management of Patients With Unstable Angina and Non–ST-Segment Elevation Myocardial Infarction -- 2002: Summary Article: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients With Unstable Angina). Circulation. 2002;106:1893