Most people with unstable angina or mild heart attack experience typical angina symptoms including chest pain that feels like squeezing, tightness, aching, or heaviness on either or both sides of the chest, as well as pain in the arms. However, a large number of patients, especially women and people over 65, tend to have atypical symptoms.1 These include:
- shortness of breath
- pain in the jaw, throat, shoulder, or neck
Who gets unstable angina or mild heart attack?
Each year about 1.4 million people are admitted to the hospital with unstable angina.2 About half of all unstable angina patients are women, and about 60% are over the age of 65. People who have unstable angina almost always also have coronary artery disease, or heart disease, which is characterized by atherosclerosis (“hardening of the arteries”). This means that there is a buildup of fatty plaque in the arteries, which makes them harder and stiffer, making it more difficult for blood and oxygen to reach the heart. This puts you at greater risk for a heart attack and related problems.
Women who have unstable angina or mild heart attack tend to be older (by about 5 years) and more often have high blood pressure, diabetes, and heart failure than men. 3, 4 Men with unstable angina or mild heart attack are more likely than women to have already had a heart attack or have undergone bypass surgery.3, 4 In addition, one study found that the majority of women (85%) with unstable angina or mild heart attack had already gone through menopause.3 Women are also more likely than men to have unstable angina rather than mild heart attack.4
What causes unstable angina or mild heart attack?
There are five major recognized causes of unstable angina and mild heart attack; more than one can be present in the same person.
The most common cause of unstable angina or a mild heart attack/NSTEMI is the development of a blood clot on top of a burst fatty plaque in the arteries. Plaque is a hardened, fatty deposit in the artery, and plaque rupture occurs when it bursts and bleeds into the artery. Your body tries to stop this bleeding in the same way it would for any other injury -- by forming a blood clot. This blood clot is not severe enough to completely block the flow of blood and oxygen (if that happened, you would have a traditional heart attack) but flow is impaired and may even be blocked intermittently. This results in chest pain.
A less common cause of unstable angina is coronary artery spasm, when the muscle in an artery of the heart involuntarily or abnormally narrows. If this occurs, you will be diagnosed with a condition called Prinzmetal's angina (or variant angina). This is a relatively rare type of unstable angina that occurs more often in men than in women.
If you have the symptoms of unstable angina but do not have signs of blockages or narrowing in the arteries of your heart, you will be diagnosed with Syndrome X. More women than men develop Syndrome X.
In some patients, unstable angina may be caused by inflammation in the arteries.5 Inflammation is your body's response to injury and disease. This response may be triggered by certain bacteria and viruses, including Chlamydia pneumoniae, which causes respiratory infections; Helicobacter pylori (H. pylori), which causes ulcers; and cytomegalovirus (CMV), which is a member of the herpes family of viruses. Unfortunately, there is little you can do to protect yourself from contracting these bacteria and viruses. See our article on infectious agents for more info.
In some patients, the original cause of the chest pain may be something other than heart disease. In these cases, you may be diagnosed with secondary unstable angina. This type of angina occurs is because some health problems can decrease the amount of oxygen available to your heart or increase your body's need for oxygen, resulting in angina without any actual heart disease. Some possible causes of secondary unstable angina include:
- excessively fast heart rate
- overexposure to thyroid hormone
- reduced blood flow due to low blood pressure
- low oxygen in the blood