Understanding Prinzmetal Angina

When Spasm in a Coronary Artery Leads to Chest Pain

460715009.jpg
SCIEPRO/Science Photo Library/Getty Images

Prinzmetal angina, also called vasospastic angina or variant angina, is a relatively uncommon cause of chest pain. It occurs when a spasm strikes in one of the coronary arteries — the arteries that supply blood to your heart. The spasm causes part of the heart muscle to be deprived of its blood supply, and angina occurs. While Prinzmetal angina can have important consequences, including heart attack and life-threatening cardiac arrhythmias, it can virtually always be treated effectively once it is correctly diagnosed.

 

Not a Heart Attack, But May Feel Like It

The chest pain that people experience with Prinzmetal angina is indistinguishable from classic, typical anginacaused by atherosclerosis. As with typical angina, people with Prinzmetal angina will often describe a mixture of symptoms, including chest tightening, squeezing, pressure, fullness, a weight or knot in the chest, aching, or a burning sensation. Such chest “discomfort” may be accompanied by dyspnea, nausea, or sweating, and/or palpitations. These symptoms often persist for 15 minutes or more. And in contrast to typical angina, which usually occurs during exertion or stress, Prinzmetal angina more typically occurs while at rest. In fact, people most frequently experience Prinzmetal angina at the quietest time of the day —between midnight and early morning. 

This combination of symptoms sometimes causes people with Prinzmetal angina to believe they are having a heart attack.

In a way, this may not be a bad thing, because people who think they are having a heart attack are more likely to seek medical help. And the sooner Prinzmetal angina is diagnosed, the sooner it can be treated effectively.

Who Is Affected By It? What Causes It?

Anyone can develop this condition, but it's more common in women.

People who develop Prinzmetal angina are often relatively young, quite healthy, and commonly have very few risk factors for typical heart disease — with the exception of smoking. Smoking is commonly a major factor in provoking angina in this condition, because tobacco products can cause arterial spasm.

In addition to smoking, the use of cocaine or amphetamines can also provoke Prinzmetal angina. Substance abusers with Prinzmetal angina are much more likely to suffer permanent (or fatal) heart damage than non-substance abusers.

In some cases, Prinzmetal angina is thought to be caused by "endothelial dysfunction," a condition in which the inner lining (i.e., the endothelium) of the arteries does not work normally. Endothelial dysfunction is also associated with cardiac syndrome xRaynaud's phenomenon, and migraine headaches. Indeed, people with Prinzmetal's angina often are also migraine sufferers. 

How Is Prinzmetal Angina Diagnosed?

Prinzmetal angina occurs when an area within one of the major coronary arteries suddenly goes into spasm, temporarily shutting off blood flow to the heart muscle supplied by that artery.

During these episodes, the electrocardigram (ECG) shows dramatic elevations of the "ST segment" — the same ECG changes commonly seen with heart attacks. Nitrates usually relieve the spasm very quickly, returning the coronary artery back to normal.

So, the things doctors look for to diagnose Prinzmetal angina are:

  • typical “anginal” chest pain,
  • accompanied by dramatic changes on the ECG,
  • which are relieved by nitrate administration,
  • with “normal’ coronary arteries demonstrated on cardiac catheterization.

In many cases, a doctor will not be present during an actual episode of angina. That is, a person with Prinzmetal angina will come in for evaluation after the angina has gone away. In these instances, diagnostic testing may include ambulatory ECG monitoring for a period of a few weeks (looking for spontaneous episodes of angina accompanied by ECG changes), or stress testing. (While Prinzmetal angina usually occurs at rest, about 20% of people with this condition may have their angina provoked during an exercise test.)

Sometimes, however, a cardiac catheterization with “provocative testing” is necessary to make the diagnosis. Because Prinzmetal angina is caused by coronary artery spasm rather than by a fixed blockage in the artery, the catheterization usually shows “normal” coronary arteries. Further, because Prinzmetal angina is not the only kind of angina that can be seen with “normal coronary arteries, making the correct diagnosis may require a demonstration that coronary artery spasm can be provoked.

Two types of "provocation" are often used to attempt to induce coronary artery spasm — hyperventilation, and drug testing with acetylcholine or ergonovine.

Hyperventilation testing is a noninvasive test. usually performed in the early morning, when spasm is more likely to occur. With the hyperventilation test, the patient is instructed to breathe deeply and rapidly for a full six minutes — which is much more difficult than it may sound— while an ECG is being continuously recorded, and echocardiography is done to look for for signs of coronary artery spasm. This test is especially useful in people who have frequent episodes of severe Prinzmetal's angina. It tends not to be nearly as useful in those whose episodes are sporadic or infrequent.

Testing with acetylcholine or ergonovine is performed during a cardiac catheterization. This kind of testing yields the correct diagnosis more reliably than the hyperventilation test. In this test, one of these drugs is injected intravenously (ergonovine) or directly into a coronary artery (acetylcholine). In people with Prinzmental angina, this often provokes the same localized coronary artery spasm that causes their symptoms. This localized spasm can be visualized during the catheterization procedure. Currently, testing with acetylcholine is considered safer than testing with ergonovine, and is the preferred invasive provocative test.

What Are the Consequences of Prinzmetal Angina?

While in general the outlook of patients with Prinzmental angina is quite good, this condition can cause serious problems. It can trigger dangerous and potentially fatal cardiac arrhythmias, especially ventricular fibrillation. And while heart attacks are uncommon with Prinzmetal angina, they indeed can occur, producing permanent damage to the heart muscle. Adequate treatment of Prinzmental angina greatly reduces the risk of such complications. In fact, once on effective treatment, people with this condition can expect to lead full, healthy lives.

How Is Prinzmetal Angina Treated?

If you have Prinzmetal angina, it will be important for you (as it is with everybody) to control all your cardiac risk factors. But in your case it is especially critical to avoid tobacco products, which are powerful stimulants of coronary artery spasm.

It is likely that you and your doctor will be able to gain excellent control over your episodes of angina with nitrates and/or calcium channel blockers. Also, you might discuss with your doctor the use of a statin — a class of drugs that not only lower cholesterol but also improve endothelial function — as recent data suggests that statins can help to prevent coronary artery spasm. 

Drugs that can trigger coronary artery spasm and which you generally ought to avoid include many beta blockers, and some migraine drugs — in particular, sumatriptan (Imitrex).

Sources:

Beltrame JF, Crea F, Kaski JC, et al. International Standardization of Diagnostic Criteria for Vasospastic Angina. Eur Heart J 2015.

Kusama Y, Kodani E, Nakagomi A, et al. Variant Angina and Coronary Artery Spasm: the Clinical Spectrum, Pathophysiology, and Management. J Nippon Med Sch 2011; 78:4.

Ong P, Athanasiadis A, Borgulya G, et al. Clinical Usefulness, Angiographic Characteristics, and Safety Evaluation of Intracoronary Acetylcholine Provocation TYesting Among 921 Consecutive White Patients With Unobstructed Coronary Arteries. Circulation 2014; 129:1723.

Stern S, Bayes de Luna A. Coronary Artery Spasm: a 2009 Update. Circulation 2009; 119:2531.

Continue Reading