What is Prinzmetal’s angina?
Prinzmetal’s angina is a form of chest pain, pressure, or tightness (angina) caused by spasms in the arteries that supply blood to the heart. It is a form of unstable angina, meaning that it occurs at rest, often without a predictable pattern. This is in contrast to stable angina, in which chest pain occurs in a predictable pattern during exertion or exercise.
Episodes of chest pain caused by Prinzmetal’s angina usually occur in clusters, with periods of frequent episodes lasting for a few months followed by weeks or months with no chest pain episodes. The pain usually occurs between midnight and approximately 8:00 AM. Prinzmetal’s angina may have no identifiable trigger, or may be brought on by hyperventilation, exposure to cold, or extreme emotional stress.
Prinzmetal’s angina is named after the researcher who first noted that coronary artery spasms were to blame. It is also called variant angina because of the unusual pattern of chest pain episodes.
What causes Prinzmetal’s Angina?
The chest pain of Prinzmetal’s angina is caused by coronary artery spasm – an abnormal or involuntary constriction of the muscle in an artery of the heart. This spasm makes the diameter of the artery smaller, restricting the supply of blood and oxygen to the heart, causing chest pain. In rare cases if the spasm is not stopped it can lead to a heart attack.
How common is Prinzmetal’s Angina and who is likely to have it?
Prinzmetal’s angina is relatively rare and the actual number of cases is not well documented. Some estimate that 4 out of every 100,000 Americans have it, or about 2% to 3% of people with chest pain who undergo an X-ray of the heart called a cardiac catheterization (also known as an angiogram). Men are more likely to suffer Prinzmetal’s angina than women: about 70% to 90% of patients are male. It also seems to be more common among Japanese people than Caucasians. However, Caucasian women are more likely than Japanese women to have Prinzmetal’s angina. People with Prinzmetal’s angina are generally younger than those with stable angina; the average Prinzmetal’s angina patient is between 51 and 57 years old. They also have fewer risk factors for heart disease with the exception of smoking, which is the most significant risk factor for coronary artery spasm.
The majority of people with Prinzmetal’s angina also have coronary artery disease, characterized by atherosclerosis (“hardening of the arteries”). This means there is a buildup of fatty plaque in the arteries of the heart, making the arteries stiffer, thus making it more difficult for blood and oxygen to reach the heart. Prinzmetal’s angina alone rarely causes a heart attack, but heart attacks may occur more often in patients with severe underlying heart disease. There is also a very slight risk of sudden death (about 2%) in people with Prinzmetal’s angina. Coronary artery spasms can also be “silent” – meaning they occur without any symptoms.
What are the symptoms of Prinzmetal’s angina?
The chest pain from Prinzmetal’s angina often has the following characteristics:
- Located under the chest bone
- Described as squeezing, constricting, tightness, pressure, or crushing, which is usually severe and may radiate to the neck, jaw, shoulder, or arm
- Often occurs at rest
- May occur at the same time each day, usually between 12:00 midnight and 8:00 AM
- Lasts from 5 to 30 minutes
- Relieved by nitroglycerin
- Can cause fainting or loss of consciousness
What causes coronary spasms?
It is not known exactly what causes coronary spasms. They may be due to problems with the thin lining of the blood vessels called the endothelium. Usually the artery lining produces a chemical (nitric oxide) that widens the blood vessel allowing blood to flow through with ease. If the artery lining is damaged or isn’t working properly, the blood vessels may narrow more easily, which may cause a coronary spasm. This idea is supported by research done in women. Levels of the artery-widening chemical are higher when estrogen levels are also high at certain stages of the menstrual cycle. Studies have shown that during these times when estrogen levels are high, women have fewer chest pain attacks. In addition, smokers tend to have lower levels of nitric oxide in their blood vessels than nonsmokers, and smoking is a major risk factor for coronary spasm.
However, there is also research suggesting that the nitric oxide theory doesn’t fully explain Prinzmetal’s angina. Atherosclerosis, the hardening of the arteries caused by the buildup of fatty plaque, impairs the release of the artery-widening nitric oxide, but not everyone with atherosclerosis develops coronary artery spasms. Other suggested causes include problems in part of the nervous system (brain and spinal cord) or the muscle tissue involved in making the arteries narrow and widen. Another possibility is that injuries to the lining of the arteries expose the muscle to chemicals that cause the blood vessels to narrow.
Prinzmetal’s Angina – Diagnosis & Treatment
How is Prinzmetal’s angina diagnosed?
Prinzmetal’s angina is often diagnosed with an ECG (electrocardiogram or EKG) during an episode of chest pain. The ECG may show a particular pattern called ST-segment elevation—a bump on a graph of the heart’s electrical activity that shows up in a telltale place. The pattern will disappear when the chest pain resolves. If you do not have heart disease (meaning an X-ray of your heart shows no major blockages in the arteries of your heart) or have only mild heart disease, and this pattern appears during ECG testing, you will probably be diagnosed with a Prinzmetal’s angina. If you have heart disease, this particular ECG pattern is may indicate that you are having a heart attack.
The gold standard for confirming a diagnosis of Prinzmetal’s angina is the coronary angiogram, a test that produces an X-ray of the heart’s arteries on a monitor. The physician will give you medication to see if it induces a spasm (the spasm will be visible on the monitor). If a focal spasm (a spasm at just one spot, rather than all over) occurs and you have ST-segment elevation on an ECG, you have Prinzmetal’s angina.
How is Prinzmetal’s angina treated?
Prinzmetal’s angina is treated with medications, specifically nitroglycerin (NTG), long-acting nitrates, and calcium channel blockers — all of which widen or open the blood vessels and improve blood and oxygen flow to the heart muscle. Calcium channel blockers are generally prescribed first. If you continue to experience episodes of chest pain, then a different class of calcium channel blocker or a long-acting nitrate may be given. For people who do not respond well to either of these drugs, alpha blockers can be prescribed. Alpha blockers lower blood pressure and reduce blood vessel narrowing by blocking the action of stress hormones. Nitroglycerin is used when you are experiencing a spasm to stop it, thereby alleviating pain; it is not used as a preventive medication. Nitroglycerin is usually given as a spray that you use in your mouth or a tablet that you place under your tongue.
Risk factor modification is also important because most people with Prinzmetal’s angina also have heart disease and are therefore at risk for a heart attack. It is especially important to stop smoking because smoking increases the likelihood of coronary artery spasms. By lowering your risk factors, you will reduce your chances of developing atherosclerosis. In addition, people diagnosed with Prinzmetal’s angina should avoid exposure to cold and high stress situations since these can trigger spasms.
What is the prognosis for people with Prinzmetal’s angina?
With medication, the prognosis is very good for people with Prinzmetal’s angina, and their chest pain can be treated successfully. One study found that 97% of patients survived 5 years after being diagnosed with Prinzmetal’s angina, and 83% survived without having a heart attack. Another study of 202 patients (18% female) who were diagnosed with variant angina between 1991 and 2002 found that 80% survived without a heart attack, and that most negative events happened within a month of when the patient first started having symptoms.
Prognosis is closely tied to the extent of coronary artery disease, and people with more severe heart disease have worse outcomes than those with less severe or no heart disease. The severity of the spasm, and how completely it blocks blood flow to the heart, may also predict outcomes: in one study, people who had ST-elevation on an ECG were 3 times as likely to die or have a heart attack than those who did not, independent of the extent of their coronary artery disease.9 Variant angina also increases the risk of developing a cardiac arrythmia (heart rhythm disorder), and there is a small but significant risk of sudden cardiac death. Sudden cardiac death occurs most often in people who have spasm in multiple arteries and have experienced an arrhythmia before during a chest pain attack.