Angina pectoris is a feeling of tightness, squeezing, or pain in the chest. It happens when the heart does not get enough oxygen-rich blood. Angina can occur in men and women of any age, but it is more common among the middle-aged and older adults.

Angina may be caused by any condition that affects the blood flow to your heart, such as:

• Coronary artery disease: The walls of the arteries that carry blood to the heart develop atherosclerosis (fatty deposits). This restricts the flow of blood so that less oxygen reaches the heart muscle. This is by far the most common cause of angina.
• Coronary artery spasm: Muscles in the wall of the coronary artery can go into spasm. This narrows the artery and causes blood to slow or stop flowing through it. When the spasm stops, the artery and blood flow return to normal.
• Abnormal heart valves that cause the heart muscle to get too thick.
• Abnormal heart rhythms.
• Anemia: The levels of red blood cells or hemoglobin (the oxygen-carrying chemical in the blood) are too low.
• Polycythemia: The blood has too many red blood cells, which causes the blood to thicken.
• A thyroid problem.
• Uncontrolled high blood pressure.

You are more likely to have angina when your heart is working harder (Stable Angina), for example, when:

• You are exercising, or doing heavy physical labor (Stable Angina).
• You are upset (Variant Angina).
• You are in cold air (Variant Angina).
• You are digesting a big meal.

However, you can also have angina when you are resting or sleeping (Unstable Angina).