What is unstable angina?
Unstable angina is a type of chest pain, pressure, or tightness (angina is the medical term for this) that is unpredictable because it is not triggered by anything specific, such as exertion or stress, which is the case with stable angina. Unstable angina is considered a more serious condition because it carries a higher risk of dying or having a heart attack. Compared with people with stable angina, unstable angina patients sometimes experience chest pain more frequently, more severely, and while resting. Chest pain that does not go away within 15 minutes or chest pain that is getting progressively worse may signal unstable angina.
What is a mild heart attack?
During a “typical” heart attack, a blood clot lodges in one of the small arteries of the heart, blocking blood flow to the heart. This produces an easily identifiable pattern on ECG or electrocardiogram testing, called ST-segment elevation. However, some people do not have complete blockage in the artery; instead the clot interrupts the blood flow only intermittently. This type of “mild heart attack” does not produce the typical heart attack pattern on the ECG. The pattern produced is usually called non-ST-segment elevation. The medical term for this type of mild heart attack is non-ST – segment myocardial infarction or NSTEMI (pronounced “en-stemee”).
What is the difference between unstable angina and a mild heart attack?
Whether you are diagnosed with unstable angina or a mild heart attack (NSTEMI) depends on your ECG pattern and the results of blood tests. The two are similar in terms of symptoms and causes; however, during a mild heart attack, the blood flow to the heart will be reduced so much that the heart muscle becomes damaged. When the heart muscle is damaged, proteins from the damaged heart muscle are released into the blood; these proteins can be detected in a simple blood test. The most common proteins measured are the troponins and creatine kinase-MB (or CK-MB for short). If you test positive for these proteins, you will be diagnosed with NSTEMI or a “mild heart attack.” If your blood tests are negative (that is, no proteins are present) then you will likely be diagnosed with unstable angina.
Mild Heart Attack – Symptoms & Causes
What are the symptoms of unstable angina and mild heart attack?
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. 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. 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. 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. In addition, one study found that the majority of women (85%) with unstable angina or mild heart attack had already gone through menopause. Women are also more likely than men to have unstable angina rather than mild heart attack.
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.5Inflammation 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
Mild Heart Attack – Diagnosis & Treatment
Why is it important to accurately diagnose unstable angina or mild heart attack?
Unstable angina or mild heart attack may appear on the surface to look like stable angina, a lower risk condition, or a typical heart attack, a high-risk condition. It is important that your condition is accurately diagnosed because the recommended treatments differ depending on whether you are at a high or lower risk.
How is unstable angina/mild heart attack different from stable angina?
The major way that unstable angina is distinguished from stable angina is by the description of your chest pain characteristics. In stable angina, chest pain is usually brought on by exertion or stress and relieved with rest. Episodes last about 1 to 15 minutes, and they follow a predictable pattern. Unstable angina often occurs when a person is at rest, and there is no discernable pattern. Unstable angina episodes occur more frequently than stable angina, are more severe, and may last longer than 15 minutes.
How is unstable angina/mild heart attack different from a typical heart attack?
Unstable angina or a mild heart attack is distinguished from a typical heart attack by examining the pattern produced during ECG (electrocardiogram) testing. An ECG is a graph of your heart’s electrical activity; if there is a rise in a specific area of the graph — ST-segment elevation — you will be diagnosed with a typical heart attack. If the pattern is described as non-ST-segment elevation, you will be diagnosed with unstable angina or a mild heart attack.
What other tests are used if I have unstable angina/mild heart attack?
If stable angina and typical heart attack are ruled out you will then be diagnosed with either unstable angina or mild heart attack. These two conditions are differentiated on the basis of blood tests for certain proteins that are only released when the heart muscle is damaged by a heart attack.
Once unstable angina or mild heart attack is diagnosed, it is likely that you will undergo further testing to determine the location and severity of the blockages in the arteries of the heart. Possible noninvasive tests include stress ECG, an echocardiogram (ultrasound of the heart), or nuclear imaging. A more detailed but invasive test is an angiogram, or X-ray of the coronary arteries.
What are the treatment goals for unstable angina/mild heart attack?
There are several goals for the treatment of unstable angina, including reducing chest pain and preventing future heart attacks and heart problems by reducing your overall heart disease risk. These are accomplished with medication and by reducing heart disease risk factors.
The ABCDE mnemonic summarizes the recommended treatments and lifestyle changes:
- Aspirin and anti-angina medication
- Beta blockers and blood pressure
- Cholesterol and cigarettes
- Diet and diabetes
- Education and exercise
What medications are used to treat unstable angina/mild heart attack?
There are several types of medication that you may be given if you have unstable angina. Most likely you will be given nitroglycerin (usually as a spray to use in your mouth) to take when experiencing angina pain that does not go away after 2 or 3 minutes. Nitroglycerin widens and opens your blood vessels, and allows blood and oxygen to reach your heart more easily. Nitroglycerin is an anti-ischemic drug meaning itprevents ischemia when blood flow to the heart is restricted and the heart doesn’t get enough oxygen. You may be given other anti-ischemic drugs such as beta blockers or calcium channel blockers. These medications also work by allowing more blood and oxygen flow to the heart, which reduces the chance of chest pain occurring.
You may also be told to take aspirin once a day because it reduces inflammation and prevents blood clots from developing. In addition, you may be prescribed clopidogrel(Plavix), which is also a blood thinning medication. Plavix works by making the blood less sticky and thus less likely to clot. It is important to note that some studies have shown that women with unstable angina are less likely than men to receive certain medications, such as aspirin and other antiplatelets.
What if I also have heart disease risk factors?
Because most people with unstable angina have some form of heart disease, it is also important to control your heart disease risk factors to reduce your chances of suffering a heart attack. If you smoke, you should quit. You should also try to exercise several times a week and maintain a healthy weight and heart-healthy diet. Your healthcare provider should discuss with you what type of exercise is appropriate for you. If you have high cholesterol, you may be given a lipid-lowering medication, such as a statin (e.g., Lipitor). It is also important to control high blood pressure; this can by accomplished with beta blockers or calcium channel blockers that you may already be taking. If you have diabetes, it is important that you keep this under control as well. Modifying your heart disease risk factors is also the only way to prevent unstable angina from developing in the first place.
Will I need stents or bypass surgery?
Some people with unstable angina or mild heart attack can be managed with medication alone, but others may need to undergo angioplasty and stenting or bypass surgery. Whether you need one of these procedures depends on the severity of your underlying heart disease and whether medicine successfully relieves your chest pain.
For the past few years, researchers have been comparing two types of treatment: a conservative strategy using medications first and saving invasive procedures (such as stents and bypass surgery) for patients who do not respond to medication treatment versus a more aggressive strategy where the patient is sent immediately for cardiac catheterization and then treated with stents or bypass surgery. The aggressive strategy reduces the risk of dying or having a heart attack in high-risk patients, including women. High-risk patients are those who show signs of damage to their heart muscle—high levels of proteins show up in their blood tests.
It is not as clear, however, whether patients at lower risk receive the same benefits. Some studies have shown that men, but not women, have better outcomes when an early invasive procedure is used,11, 12 but other studies have shown that both men and women do better when an early invasive procedure is performed. If you are lower risk and your pain persists after medication treatment, stents or bypass surgery may still be your best option for getting rid of your chest pain and improving your quality of life.