Basic Facts
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Angina pectoris, or angina, is a symptom of chest pain or pressure that occurs when the heart is not receiving enough blood and oxygen to meet its needs.
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Angina results from coronary artery disease (CAD), which is an accumulation of plaque inside the coronary blood vessels.
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There are two types of angina – stable and unstable.
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Stable angina usually occurs in a predictable fashion during or after physical exercise or emotional stress.
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Unstable angina occurs in unexpected or unpredictable times, such as at rest.
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Unstable angina symptoms are a medical emergency, and may be a precursor for a heart attack. Thus, medical attention should be sought immediately.
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A More Detailed Explanation
Angina pectoris, or angina, is a symptom of chest pain or pressure that occurs when the heart is not receiving enough blood and oxygen to meet its needs. In general, angina results from plaque made of cholesterol or other fats building up in the coronary arteries. The accumulation of this plaque is known as coronary artery disease (CAD). When enough plaque accumulates inside a person's coronary arteries, blood flow past the plaque is reduced, depriving the heart muscle of its needed nutrients and oxygen. As a result, angina symptoms can occur. Angina is more likely to occur when the heart is working harder and requiring additional blood flow, such as during physical activity or emotional stress.
Angina is classified into two types – stable angina and unstable angina.
Stable angina results from the gradual accumulation of plaque in the coronary artery. As this accumulation increases, angina symptoms begin to occur in a predictable fashion during or after physical exercise or emotional stress. This predictable pattern can persist for weeks, months, or even years. The kinds of activities that can cause stable angina include walking up a hill or a flight of stairs, doing housework, experiencing severe emotional stress or anxiety, having sex, exposure to cold temperatures, or consumption of heavy meals. Although the symptoms are bothersome, they do not usually indicate that a heart attack is imminent.
Unstable angina results from the sudden rupture of a plaque, which causes a rapid accumulation of platelets at the rupture site and a sudden increase in obstruction to blood flow in the coronary artery. As a result, unstable angina symptoms occur suddenly, often in an unexpected or unpredictable fashion. The symptoms may be new, prolonged, more severe, or occur with little or no exertion. Unstable angina may also be less responsive to nitroglycerin medication than stable angina.
Unstable angina is a medical emergency
. Unchecked, the accumulation of platelets and obstruction to blood flow can result in a heart attack. This risk of heart attack remains even if the unstable angina symptoms lessen or disappear. Thus, if unstable angina occurs, seeking immediate medical attention is very important.
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Unstable Angina Symptoms
Unstable angina pain can last between 5 and 20 minutes. Sometimes the symptoms can ‘come and go’. The pain associated with angina can vary from person to person, and people make different comparisons to express the pain they feel. Many people describe unstable angina as:
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Pain or pressure
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Tightness
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A heavy, crushing feeling in the chest, neck, throat, jaw, shoulder and/or arm
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Discomfort just below the breastbone
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Burning similar to heartburn or indigestion
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Shortness of breath
Because unstable angina occurs without warning and during rest, it can cause severe anxiety. Unstable angina sometimes brings about other symptoms such as nausea, lightheadedness, or profuse sweating. The pain from angina may subside if a person takes nitroglycerin.
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Unstable Angina Risk Factors
Unstable angina results from coronary artery disease (CAD). Thus, risk factors for the development of CAD are also risk factors for unstable angina:
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Smoking
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Having high cholesterol levels
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Not exercising regularly
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Having hypertension
, or high blood pressure
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Eating a diet high in saturated fat and cholesterol
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Having diabetes mellitus
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Being more than 30 percent over one's ideal weight
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Having family members (especially parents or siblings) who have had coronary artery disease (CAD) or a stroke
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Using stimulant or recreational drugs, such as cocaine or amphetamines (these substances do not cause CAD but can increase the impact of any underlying CAD)
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Unstable Angina Diagnosis
To diagnose unstable angina pectoris, a physician will take a thorough medical history (including a complete description of a patient’s symptoms), conduct a physical exam, measure blood pressure, and perform one or more of the following tests:
Electrocardiogram (ECG)
ECG tests monitor the electrical activity of the heart. When certain ECG findings are present, the risk of unstable angina progressing to a heart attack is significantly increased.
Cardiac blood tests
Since unstable angina can be a precursor for a heart attack, a physician will usually order blood tests to determine if a heart attack has occurred. The test looks for evidence that heart muscle has died. Usually, several blood tests have to be checked over a period of several hours, since evidence of a heart attack can take some time to appear in the blood. Knowing the results of these tests is important in determining the next best cardiac test or treatment to have.
Cardiac catheterization and angiography
Physicians may recommend cardiac catheterization and angiography, especially if significant resting ECG changes are present or cardiac blood tests are abnormal. During angiography, a catheter is inserted into an artery in the groin or arm and advanced into the heart. When the catheter is positioned near the arteries that supply blood to the heart, the physician injects a contrast dye. As the dye travels through the arteries, X-ray pictures are taken to see how well blood flows through the arteries, and if there are any blockages that indicate CAD.
ECG stress test
In an ECG stress test, the patient exercises, usually by walking on a treadmill, while wearing an ECG monitor. If the heart is not receiving sufficient oxygen during the exercise, the ECG patterns reflect this and indicate the presence of CAD. If a person is unable to perform enough exercise to stress the heart adequately during a stress test, a drug designed to mimic the effects of exercise on the heart can be administered instead.
Nuclear stress test
A nuclear stress test is similar to an ECG stress test. However, during the exercise, a radioisotope (a safe radioactive compound) is injected into a vein and travels to the arteries that supply blood to the heart. After exercise, pictures of the heart are taken with a special camera that can detect the radioisotope. These pictures can determine if blockages from CAD are present.
Echocardiographic stress testing
An echocardiographic, or echo, stress test is similar to an ECG stress test. An echo stress test uses ultrasound waves to take pictures of the heart before and after exercise, which can show changes that indicate the presence of CAD.
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Unstable Angina Treatment
Treatment for unstable angina focuses on three goals: stabilizing any plaques that may have ruptured in order to prevent a heart attack, relieving symptoms, and treating the underlying coronary artery disease (CAD).
Stabilizing the plaque
The cornerstone of stabilizing a ruptured plaque is interrupting the clotting process that can lead to a heart attack. Patients who experience the symptoms of unstable angina and who are not taking aspirin should immediately chew an aspirin, which blocks clotting factors in the blood. Chewing the aspirin, rather than swallowing it whole, accelerates the body’s process of absorbing the aspirin. When unstable angina occurs, the patient should seek immediate medical attention at a hospital. Once at the hospital, other medicines to block the body’s clotting process may be administered, including heparin, clopidogrel, and platelet glycoprotein (GP) IIb/IIIa receptor blocker medications.
In some cases, a procedure to reduce or stabilize the blockage in the coronary artery may be needed in addition to the anti-clotting medications. The most common procedure for this is coronary angioplasty. In coronary angioplasty, a balloon-tipped catheter is inserted into a blood vessel in the arm or groin and is advanced through blood vessels and into the heart. When the catheter reaches the blockage in the coronary artery, the physician inflates the balloon on the tip of the catheter. The balloon is inflated and deflated, pressing against the plaque buildup on the walls of the coronary artery and increasing the diameter of the artery. Often, a metal-mesh tube, known as a stent, is placed in the artery to keep it open. The stent remains permanently in the coronary artery, and the balloon and catheter are removed at the end of the procedure.
Relieving symptoms
Both angina medications and procedures to reduce blockages in the coronary arteries can relieve the symptoms of unstable angina. Depending on the circumstances of the individual patient, medications alone or medications in combination with a procedure may be used to treat angina.
Angina medications
1. Nitrates: Commonly known as nitroglycerin, nitrates are the most commonly prescribed drugs to treat angina. Nitrates dilate blood vessels, which allow more blood to flow past blockages. Nitrates also decrease the resistance the heart faces when pumping blood to the rest of the body, which in turn can decrease the stress (workload) on the heart.
2. Beta-blockers: Beta-blockers slow the heart rate and decrease the force of heart muscle contraction, thereby reducing the stress on the heart.
3. Calcium channel blockers: Calcium channel blockers cause blood vessels to dilate and blood pressure to decrease, and they also reduce the frequency and severity of angina by reducing the stress on the heart.
For more detailed information about any of these angina medications, see Anti-Anginal Therapy.
Angina procedures
1. Coronary angioplasty: As described above, during coronary angioplasty, a balloon-tipped catheter is inserted into a blood vessel in the arm or groin and is advanced through blood vessels and into the heart. When the catheter reaches the blockage in the coronary artery, the physician inflates the balloon on the tip of the catheter. The balloon is inflated and deflated, pressing against the plaque buildup on the walls of the coronary artery and increasing the diameter of the artery. Often, a metal-mesh tube, known as a stent, is placed in the artery to keep it open. The stent remains permanently in the coronary artery, and the balloon and catheter are removed at the end of the procedure.
2. Coronary artery bypass grafting (CABG) surgery: When the blockages are too numerous or difficult to be treated with coronary angioplasty, CABG surgery may be needed. This is an open-heart surgery, performed by cardiac surgeons. After the patient is put to sleep, the chest is surgically opened and new, unclogged blood vessels, taken from a person's leg or chest, are used to reroute, or bypass, the plaque blockages.
Treating coronary artery disease (CAD)
CAD is treated with medications and lifestyle modifications.
Coronary artery disease (CAD) medications
1. Aspirin: Aspirin prevents platelets, which are tiny plugs that can come together to form blood clots, from accumulating at the site of plaque that has broken apart. Patients with CAD need to take this medication indefinitely to lower their risk of a heart attack.
2. Lipid-lowering agents: Cholesterol-lowering medications, such as statins and other lipid therapies, have been associated with marked reductions in future cardiac events by stabilizing plaques and decreasing their risk of rupture. Almost all patients who have experienced unstable angina will benefit from long-term lipid therapy. Different therapies may be required based on the patient's individual cholesterol levels.
3. CAD risk factor treatments: Medications that specifically treat the risk factors for CAD (e.g. high blood pressure and diabetes) are needed to control the growth of plaques. Depending on an individual patient’s situation, a physician will prescribe the necessary medications for this.
Coronary artery disease (CAD) lifestyle modifications
1. Healthy diet: Patients with coronary artery disease (CAD) who consume diets lower in saturated fat, cholesterol, and calories can improve their cholesterol readings. In addition, patients with CAD who consume a diet rich in fruits, vegetables, and low-fat dairy products, and low in red meat and processed foods (known as the DASH diet) can lower their blood pressure.
2. Exercising regularly: Aerobic exercise for 20 to 30 minutes every day can reduce blood cholesterol levels and improve blood pressure. Patients with angina should check with their physician before beginning an exercise program.
3. Quitting smoking: Smoking accelerates the progression of CAD, diminishes the blood's capacity to carry oxygen to body tissues, damages the blood vessel walls, and makes the blood more likely to clot, leading to heart attack and stroke. The nicotine and other chemicals in tobacco smoke also raise blood pressure and increase the heart rate. By quitting smoking entirely, the risk of heart attacks is greatly reduced.
4. Losing weight: Losing as few as 5 to 10 pounds can help decrease high blood pressure and improve cholesterol.
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Variant angina
An uncommon form of angina that occurs at rest and may be confused with unstable angina is called variant or Prinzmetal’s angina. Variant angina occurs when the coronary artery suddenly contracts, or spasms. It occurs due to the presence or absence of certain hormones or other substances in the blood. When spasm occurs, the artery can narrow, blocking normal blood flow and causing symptoms of angina. Though the symptoms can be very concerning, this condition rarely results in a heart attack, is usually temporary, and can be effectively treated with anti-spasm medications. However, because the symptoms of variant angina closely mimic those of unstable angina, persons should seek immediate medical attention, rather than attempt to distinguish the two conditions on their own.
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Differences between stable angina, unstable angina, and heart attack (myocardial infarction)
Although stable angina, unstable angina and heart attacks are all caused by coronary artery disease (CAD), they are not the same thing. Angina is a symptom that occurs when a CAD plaque blocks sufficient blood flow to the heart. Angina is classified into two types – stable and unstable.
Stable angina results from the gradual accumulation of plaque in the coronary artery. It is usually predictable, associated with physical and emotional stress, and relieved with rest and/or nitroglycerin pills. Stable angina symptoms do not cause permanent damage to heart muscle.
Unstable angina results from the sudden rupture of a plaque, which causes a rapid accumulation of platelets at the plaque and obstruction of blood flow in the coronary artery. Accordingly, unstable angina symptoms occur in an unexpected or unpredictable fashion, such as at rest. The symptoms may be more severe and less responsive to nitroglycerin medication. Unstable angina is a medical emergency. Unchecked, it can result in a heart attack. This risk of heart attack remains even if the unstable angina symptoms lessens or disappears. Thus, if unstable angina occurs, seeking immediate medical attention is very important.
A heart attack, or myocardial infarction
, occurs when heart muscle dies. This usually results when a CAD plaque breaks apart, or ruptures, and the coronary artery ends up completely blocked by a platelet plug. Any CAD plaque, even one that is not large enough to cause angina, can rupture, leading to complete blockage of the artery and heart muscle death. Heart attack symptoms are similar to unstable angina, but are usually more severe and prolonged. Because symptoms alone may not distinguish between unstable angina and heart attack, both conditions are considered medical emergencies, and medical attention is needed immediately.
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Sources
Content developed by Thomas Maddox, MD, FACC and the American College of Cardiology
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